Challenges in community-based recruitment of Alzheimer's disease cases: Experience of the monitoring drug efficacy through multi-omics research initiative in Alzheimer's disease (MEMORI-AD) study

Abstract

Background

The Monitoring drug Efficacy through Multi-Omics Research Initiative in Alzheimer's Disease (MEMORI-AD) study aims to characterize drug response to donepezil and memantine in a Filipino cohort with late-onset Alzheimer's disease (AD). To enhance enrollment, community-based dementia screening and recruitment were conducted across barangays in Manila.

Objective

This study describes the experiences and challenges in community-based recruitment for multi-omics research in vulnerable populations.

Methods

After coordinating with local officials for approval, recruitment targeted residents aged 65 years and above. A public health lecture on dementia was held, followed by rapid screening using the “10 Warning Signs of Dementia” questionnaire by the Alzheimer's Disease Association of the Philippines and the AD-8 Dementia Screening Interview. Eligible participants were invited for clinical screening, including laboratory work, neuropsychological tests, and neuroimaging. Reasons for non-consent and withdrawal were recorded.

Results

Of 301 eligible participants, 42 (14.0%) were suspected of dementia and eligible for work-up. Among them, 14 (33.3%) did not consent, 15 (53.6%) initially consented but withdrew, and 13 (46.4%) completed the assessment. Only 2 patients were enrolled. The main cause for non-consent was disinterest (n = 8, 57.1%), followed by unavailability of a legally authorized representative (LAR) (n = 3, 21.4%), which was also the primary reason for withdrawal (n = 9, 60%).​

Conclusions

Recruitment of vulnerable Filipinos in multi-omics research within a lower-middle income country faced significant barriers, encompassing economic, psychosocial, and health constraints, largely due to disinterest and unavailability of LAR. Further studies on family dynamics, socioeconomic, and cultural factors could offer insights to overcome these recruitment barriers.

Trial Registration Number

Philippine Health Research Registry ID PHRR230220-0054116; ClinicalTrials.gov ID NCT05801380.

Introduction

Dementia is a growing public health concern in the Philippines, with a prevalence of 10.6% among individuals aged 60 and above, of which 85.5% are attributed to Alzheimer's disease (AD). ¹ Globally, the World Health Organization identifies dementia as the seventh leading cause of death and one of the major causes of years lived with disability. In the Philippines, the burden is projected to increase substantially, with the number of people living with dementia expected to reach 1,159,000 by 2050.^2,3 These figures highlight the urgent need for interventions and research to address the challenges posed by dementia and related neurodegenerative diseases in the country.

Pharmacological management of AD commonly involves acetylcholinesterase inhibitors, such as rivastigmine, donepezil, and galantamine, administered either as monotherapy or in combination with memantine for moderate to severe disease. ⁴ However, local evidence on the safety and efficacy of these medications among Filipino patients remains limited. In addition, although the gut–brain axis is increasingly recognized as a key pathway in neurodegenerative diseases, data from the local context are scarce, leaving treatment responses and potential adverse effects in Filipino patients with AD insufficiently characterized. ⁵

In line with the Philippine Mental Health Act, which emphasizes the development of context-specific mental health research and care strategies, ⁶ the Monitoring drug Efficacy through Multi-Omics Research Initiative in Alzheimer's Disease (MEMORI-AD) study was designed as a descriptive, prospective cohort study to investigate drug response among newly diagnosed Filipinos with late-onset AD using a multi-omics approach.^7–9 Given the study's longitudinal design and data-intensive procedures, robust participant recruitment was essential to its implementation.

Participant recruitment for the MEMORI-AD study was conducted through multiple pathways. ⁷ While hospital-based study sites served as the primary source of participant enrollment, a supplementary community-based recruitment strategy was implemented to enhance case identification and reach individuals who may not yet be engaged in formal dementia care. We would like to emphasize that this paper exclusively focuses on the recruitment challenges encountered during the community-based recruitment phase of the MEMORI-AD study; recruitment processes and outcomes from hospital-based study sites are beyond the scope of this report.

Recruitment and retention remain persistent challenges in Alzheimer's disease and related dementias (ADRD) research, particularly in longitudinal and community-based studies. Prior literature has identified caregiver burden, requirements for legally authorized representatives, comorbidities, stigma surrounding cognitive decline, and logistical constraints as major barriers to sustained participation.^10–13 These challenges disproportionately affect older adults in low- and middle-income settings, where health system limitations, financial insecurity, and cultural perceptions of aging further shape research engagement.^14,15 Despite growing recognition of these issues globally, empirical evidence describing how such barriers operate within specific sociocultural contexts, particularly in the Philippines, remains limited.

The community-based recruitment was carried out in collaboration with local government units across three districts of Manila and involved 15 barangays—the smallest administrative unit in the Philippines, comparable to a village or neighborhood within a city or municipality (Figure 1). ¹⁶ The approach included community engagement activities, dementia awareness efforts, and coordination with local stakeholders to facilitate referrals of potential participants. Despite its role as a supplementary recruitment pathway, implementing this strategy in community settings presented distinct challenges. Limited awareness of dementia, stigma associated with cognitive decline, logistical constraints, and barriers related to healthcare access and costs significantly influenced participation. ¹⁷

Figure 1.

Spot map of 15 barangays in the community recruitment. ¹⁸

This paper describes the recruitment and retention challenges encountered during community-based enrollment for the MEMORI-AD study, situating these barriers within the broader AD literature on caregiver dependence, socioeconomic constraints, and sociocultural perceptions of dementia in the Philippine context.

Methods

The MEMORI-AD study protocol, published in the British Medical Journal Open, was approved by the relevant regulatory and ethics authorities. ⁷ The methodologies of this protocol were used and adapted into the community-based recruitment phase or site of the study. The resulting recruitment challenges were not originally anticipated in the published study protocol. However, further clearance was acquired, which covered all recruitment activities and methodologies. The methodology included collaboration with local health offices, community-based health fora regarding dementia, and pre-screening of potential participants. Individuals suspected to have dementia based on the pre-screening were invited for informed consent with their legally authorized representative (LAR) and subsequently underwent further clinical and laboratory assessments. Reasons for non-consent and withdrawal were also recorded to identify barriers to participation.

Ethical clearance

Prior to community recruitment, the study protocol received ethical clearance from the Department of Health Single Joint Research Ethics Board (SJREB-2022-15) and was approved by the University of the Philippines Research Ethics Board (UPMREB 2021-0596-01-SJREB). Meanwhile, the Manila Health Department approved the collaboration with the study and allowed the required visits in the different Manila districts targeted by the research team.

Recruitment flow

The recruitment process followed several stages (Figure 2). First, coordination was conducted with district and barangay health offices to secure support and identify target communities. Public health lectures (PHL) on dementia were then delivered in participating barangays to raise awareness and invite community members to undergo rapid pre-screening. Individuals who screened positive for suspected dementia were subsequently invited for informed consent together with their LAR. Consenting participants underwent a series of clinical screening, including cognitive assessments (i.e., Montreal Cognitive Assessment, Clinical Dementia Rating scale, and the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria), neuroimaging (i.e., plain cranial computed tomography scan), and laboratory tests (i.e., rapid plasma reagin, serum glutamic-oxaloacetic transaminase, serum glutamic pyruvic transaminase, serum vitamin B12, liver function, free thyroxine and thyroid-stimulating hormone tests) for diagnosis.

Figure 2.

Coordination with LGUs and LHCs from information dissemination to patient screening and recruitment.

At each stage, reasons for non-consent and withdrawal were documented. This allowed identification of key barriers to participation, such as unavailability of LARs, health-related comorbidities, and personal constraints, which informed the interpretation of recruitment challenges in this study.

Courtesy meeting/site visit

Courtesy meetings were held in district health offices and barangays to discuss the study objectives and recruitment process. The team also worked with barangay health workers to identify potential participants and to relay details of the PHL and recruitment activities, including the schedule and expected number of attendees.

Public health lecture

Prior to screening, a brief PHL on dementia was conducted among community members aged 65 years and above, with participation also extending to their family members. Brochures containing the study's eligibility criteria, participation details, and contact information were distributed to raise awareness on AD and encourage participation. As part of the PHL, physicians and/or supervised medical students facilitated a forum discussion that focused on the signs of dementia, its types, risk factors, and preventive measures.

Rapid screening tests

The PHL included a presentation of the 10 Warning Signs of Dementia, followed by completion of the corresponding questionnaire guided by the facilitators as part of the pre-screening process. ¹⁹ Participants with at least two positive responses in key items (items 1, 2, 4, 8, and 9) underwent a second rapid screening conducted by research assistants using a Filipino version of the AD8 screening interview, ²⁰ adapted from the original AD8 Dementia Screening Interview. ²¹

Participants were also screened based on the following exclusion criteria: (1) had a stroke (sudden slurred speech, sudden drooping of the mouth, sudden weakness in one arm or leg), (2) has been evaluated and diagnosed with depression or other psychological disorders, (3) has taken antibiotics in the past three months, (4) takes medication for diarrhea or intestinal inflammation, (5) takes large doses of probiotics, and (6) underwent intestinal surgery in the past five years.

Eligibility for further assessment

Eligibility for further diagnostic assessment at the University of the Philippines Manila–Philippine General Hospital was determined based on predefined criteria. Participants were considered eligible if they: (1) had at least two positive responses in key items of the 10 Warning Signs of Dementia questionnaire and (2) scored ≥3 on the AD8 interview (Filipino version), and (3) did not satisfy any exclusion criteria.

The cut-off ≥3 on the AD8 interview (Filipino version) provided the best balance of diagnostic sensitivity (91.5%) and specificity (77.9%). Adjusting the cut-off to ≥2 dropped the specificity (42.1%) dramatically and while the higher cut-off of ≥4 lowered the sensitivity (83%). Since the tool is validated as a rapid screening tool, the cut-off with the highest sensitivity and with the lowest trade-off of reduced specificity is the best option. ²²

Informed consent

Apart from the verbal consent, voluntary consent from eligible participants with suspected dementia were obtained through their caregiver or LAR, using the informed consent form duly approved by the ethics review board. The process was conducted through face-to-face, phone call, or video call. A LAR, as mandated by the Philippine Mental Health Act, ⁶ is a person of legal age to consent on behalf of a cognitively impaired individual. In the event that the potential participant does not have an appointed LAR, the spouse, non-minor children, parents, chief of a mental health facility, or a court-appointed individual shall act as their interim representative. Participants who consented to be part of the study were recruited and scheduled for further clinical screening.

Patient examination

Subsequent diagnostic examinations, including neuropsychological testing, neurological evaluation, cranial imaging, and laboratory investigations, were conducted at the University of the Philippines–Philippine General Hospital in accordance with the previously published protocol by the study team. ⁷ Only patients who fulfilled the established eligibility criteria were enrolled in the study.

Caregiver/LAR involvement

The study protocol did not specify a minimum duration for how long the LAR or caregiver had known the participant, nor a required number of caregiving hours per week prior to enrollment. These factors were not used as eligibility criteria. However, it was preferred that the LAR/caregiver was someone who stayed with the participant most of the time or on a daily basis, as this facilitated reliable reporting and assistance during interviews and assessments, particularly for questionnaires that required collateral information or support for participant responses.

For participation, the presence of an LAR/caregiver was required during the baseline visit to support the informed consent process and eligibility assessment. Once a participant was deemed eligible, two (2) additional study visits were required, each spaced approximately three (3) months apart. Both the participant and the LAR/caregiver were expected to attend these visits.

Each visit, including the baseline assessment, lasted approximately 2.5–3 hours, encompassing clinical evaluation, cognitive testing, and required procedures. The total anticipated study-related time commitment was therefore approximately 7.5–9 hours over a six-month period.

Data analysis

The total number of participants, including those who consented, withdrew, or declined consent, was recorded. Reasons for withdrawal and non-consent, when applicable, were also documented to identify barriers to participation. All study data were entered and managed in the Research Electronic Data Capture (REDCap) system to maintain data integrity. Data cleaning and quality checks were performed prior to the analysis.

Descriptive statistics were then employed to summarize participant characteristics and recruitment outcomes. Frequencies and percentages were calculated for categorical variables, including recruitment status, reasons for withdrawal, and reasons for non-consent. Percentages were calculated at each step of the recruitment process (e.g., proportion consenting among those eligible), rather than from the total number of participants, to reflect stage-specific participation and attrition.

Results

During community recruitment, 15 barangays were visited and 301 participants (aged 65–90 years; mean 72 ± 5.3 years; M:F = 84:217) attended the public health lectures and underwent pre-screening (Figure 3). Of these, 42 (14.0%) were suspected to have dementia and were considered eligible for further assessment, while 259 (86.0%) were deemed ineligible. Among the eligible participants, 28 (66.7%) consented and were recruited. Subsequently, 15 (53.6%) of the recruited participants withdrew their consent, leaving 13 (46.4%) to undergo diagnostic assessment. Of those assessed, 11 (84.6%) were excluded, resulting in only 2 participants (15.4%) enrolled in the study.

Figure 3.

Summary of screening, consent, recruitment, exclusion, and enrollment of participants in the MEMORI-AD study.

Figure 4(a) and (b) summarize the reasons for non-consent and withdrawal, respectively. Of the 42 eligible individuals, 14 (33.3%) did not consent to participate (Figure 4(a)). The most common reason for non-consent was a lack of interest, accounting for 57.1% (8/14) of non-consenting participants. This was followed by the unavailability of a LAR, which prevented 21.4% (3/14) of the participants from providing consent. Additional reasons included the unavailability of the patients themselves (n = 1, 7.1%) and the presence of other comorbidities (n = 2, 14.3%).

Figure 4.

Summary of the reasons for (a) non-consent and (b) withdrawal of the participants.

Among the 28 consenting participants, 15 (53.6%) discontinued participation at various stages (Figure 4(b)). The most common reason for withdrawal was the unavailability of a LAR, accounting for 9 (60%) participants. Other reasons included being diagnosed with other comorbidities at the time of the assessment, such as stroke (n = 2, 13.3%), fear of diagnostic examination (n = 1, 6.7%), conflicting schedule (n = 1, 6.7%), mobility or accessibility limitations (n = 1, 6.7%), and perceived infantilization during assessment (n = 1, 6.7%).

A total of 13 participants were successfully screened for AD diagnosis. Of these, 11 were excluded after diagnostic evaluation for not meeting the criteria for AD. As shown in Figure 5, the most common reason for exclusion was diagnosis of mild cognitive impairment (MCI; n = 9, 81.8%), followed by vascular dementia (n = 1, 9.1%), and normal cognitive findings (n = 1, 9.1%). Only 2 participants (15.4% of those screened) met the eligibility requirements and were subsequently enrolled in the study.

Figure 5.

Summary of reasons for patient exclusion.

Discussion

ADRD studies frequently encounter recruitment and retention difficulties driven by caregiver requirements, stigma surrounding dementia, comorbidities, and logistical constraints.^10–15 This study situates these challenges within the Philippine context, showing how family structures, economic precarity, cultural notions of dignity and aging, and health-related limitations interact to shape participation decisions in community-based research.

One of the primary reasons for both withdrawal and non-consent in the study was the unavailability of the caregivers or LARs, who are required to provide informed consent for individuals with impaired decision-making capacity under Republic Act No. 11036. ⁶ Beyond their legal role, caregivers or LARs are integral to study participation, as they facilitate transportation, assist during assessments, and provide supplementary information. Additional reasons for withdrawal included competing personal responsibilities, existing or worsening health conditions, physical limitations, and decisions to discontinue participation during examinations. Although initial community screening identified individuals with possible dementia, a substantial attrition occurred prior to diagnostic evaluation, underscoring a gap between case identification and sustained research engagement.

Collectively, these findings highlight how economic, psychosocial, and health-related barriers intersect to constrain both recruitment and retention in community-based AD research, while reflecting broader structural vulnerabilities related to aging, caregiving, and access to care in the Philippine context.

Family dynamics and economic constraints

Unavailability of LAR due to the independent living of older Filipinos

The majority of AD clinical research requires the enrollment of a study partner, usually a spouse or domestic partner, who can provide insights into the participant's daily cognition and functioning. ¹⁰ However, this participation requirement would not be feasible if the potential participant does not have anyone that could serve as their LAR to provide the informed consent on their behalf. This requirement particularly hinders the older Filipino adults that live independently from their relatives. In tandem with this, there is an increasing number of potential AD participants who live in isolation or do not have any qualified LAR, increasing the exclusion of possible participants.^11,12 In the Philippines, one-person households comprised 9.2% of all households in 2017, including older adults living alone. ²³ A longitudinal study in 2018 indicated that older Filipinos strongly prefer independent living. Alarmingly, 93% of the respondents do not have a primary caregiver. ²⁴ Given the aging population and the preference for living alone, this number is expected to continue to rise.

Although a court-appointed LAR is possible for those living alone, the process is lengthy and complex. It requires a formal court petition, legal representation, and substantial evidence of incapacity, such as medical and psychiatric evaluations, which are often difficult to obtain for undiagnosed or isolated individuals. ²⁵ This procedural complexity hinders their participation in the study.

Unavailability of LAR due to scheduling conflict

In cases where the potential participants have someone that could act as their LAR, their participation is further hindered by scheduling conflicts. Many potential participants relied on their children or relatives to serve as their LAR. However, these individuals often faced competing priorities such as employment, household management, and caregiving for other family members, all of which affect their capacity and inclination to participate in health protective behaviors. In the Philippine context, some LARs were employed abroad or engaged in irregular work arrangements, further complicating their availability. Moreover, 58% of the older adults in the Philippines primarily rely on their children as an income source. ²⁴ Missing a day of work to accompany a relative to the study posed not only logistical difficulties but also potential financial strain, particularly among socioeconomically disadvantaged populations. This reflects a broader, long-standing issue in the Philippines: when one family member becomes ill or requires medical care, another must accompany them, often at the expense of income due to the prevailing “no work, no pay” labor setup. This work setup is deeply embedded in the labor code of the Philippines, but along with it comes the benefits of paid leave. However, the informal sector accounts for about 70% of the employment in the Philippines, characterized by poor working conditions that lack reliable coverage from the Philippine labor and social security laws. Hence, benefits such as paid leave are often not considered, threatening their job security and income stability. ²⁶ Such circumstances highlight how economic and caregiving obligations influence health-seeking behavior and, consequently, research participation.

Overall, the lack of designated LARs among older adults poses significant implications for AD clinical research. Consequently, excluding these otherwise potential and eligible participants could suggest that the results of several AD clinical research in the Philippines might not adequately represent the population.

Unavailability of the patient

Apart from the unavailability of LAR, the limitation could also come from the patients or potential participants themselves as some older Filipino adults have other household responsibilities, which includes but not limited to employment and caregiving responsibilities. In the Philippines, older adults generally experience poor overall economic well-being. Around 49% of older adults have reported that they grew up in poverty. In their old age, only a minority of 42% receive income from their pension, and only about 20% consider it as a primary income source, suggesting its inadequacy to meet their basic needs. ²⁴ Although pensions provide some financial relief, many indigent older adults do not meet the strict eligibility criteria and are thus unable to access this government support. ²⁷ This challenging economic situation often forces them to continue working, even in old age.

According to a longitudinal study in 2018, the most commonly reported income sources among older adults, aside from the support of their children living in the country, are pension benefits (42%) and earnings from employment (34%). ²⁴ In 2022, the employment rate among older adults had increased to around 38.22%, translating to approximately 2.54 million senior citizens in the workforce. ²⁸ Along with this, grandparents acting as primary caregivers of their grandchildren is a well-documented cultural phenomenon in the country, resulting in additional responsibility. ²⁹ The extensive time commitment required for participation in a cohort study and the logistical challenges of attending study visits interfere with the existing duties of older adults. This combination of increasing responsibilities and the challenges of aging can make it demanding for older adults to allocate a specific time to participate in studies.

Psychosocial and cultural barriers

Patient disinterest due to normalization of and cultural resistance to dementia

Patient disinterest in study participation reflects deeper psychosocial and cultural perceptions of dementia within Filipino communities. While a public health lecture was conducted during recruitment, many community members still declined participation. This observation does not necessarily indicate that educational interventions are ineffective; rather, it suggests that a single, brief session may be insufficient to address deeply rooted misconceptions, stigma, and cultural beliefs surrounding dementia. Importantly, the study design did not allow differentiation between the effects of the amount of education provided and the cultural relevance or tailoring of the content. Future recruitment efforts may therefore benefit not only from repeated engagement but also from culturally informed and context-specific educational approaches that are responsive to local beliefs, values, and experiences related to aging and cognitive decline.

A study found that only 27.65% of Filipinos are knowledgeable about dementia, and poor health-seeking behaviors were observed in 72.73% of those uninformed about it. ¹⁴ Moreover, 70% of those who are aware of dementia still consider it a normal part of aging. This normalization of cognitive decline leads to dismissal of early symptoms and a lack of perceived need for diagnosis or participation in research. ¹⁵

However, this cultural acceptance of forgetfulness in old age coexists with an equally strong belief that ‘someone old is someone wise’. Filipino society traditionally associates aging with accumulated wisdom, sound judgment, and leadership. Older Filipinos often take pride in their wisdom and independence, traits deeply rooted in pre-colonial traditions that revered elders as sources of authority and knowledge.^30,31

This pattern reveals a cultural paradox. While forgetfulness is often seen as a harmless part of growing old, acknowledging it as dementia, a formal diagnosis implying cognitive decline, challenges this revered image of wisdom. Forgetting is tolerated, even normalized, but being labeled with a disease that signifies loss of intellect and autonomy threatens one's social identity.^32,33 This contradiction helps explain why many older Filipinos, despite recognizing some memory lapses, resist medical labeling or research participation related to dementia. Accepting such a diagnosis could be perceived as admitting frailty or incompetence, eroding their sense of dignity and the respect accorded to them within their families and communities.^34,35

Thus, patient disinterest may stem from sociocultural mechanisms of self-protection rather than simple disinterest or apathy. Addressing this irony requires culturally appropriate health communication that reframes dementia not as a loss of wisdom, but as a manageable condition.

Perceived infantilization during cognitive assessment

Discomfort during the cognitive assessment process further demonstrates how psychosocial perceptions influence participation. One participant withdrew from the study after feeling infantilized mid-examination. Since the study requires the use of tools to detect cognitive impairment among the participants, most tests may appear simplistic to some patients, especially those unaccustomed to formal testing. Individuals with dementia may experience distress when subjected to treatments or diagnostic tests perceived as patronizing. A narrative review highlighted that care practices which objectify or stigmatize patients, such as treating them as a homogenous group or infantilizing them, can lead to feelings of worthlessness and distress. ³⁶

Similarly, a study discussed how stigmatizing behaviors, including patronizing communication, negatively impact the psychosocial well-being of individuals with cognitive decline. The study emphasizes that such interactions can diminish self-worth and exacerbate stress in both patients and their caregivers. ³⁷

In the Filipino context, such reactions may be amplified by the cultural importance of maintaining dangal (dignity) and hiya (a sense of social propriety). ³⁴ For an older person who identifies wisdom and composure as markers of respect, being subjected to questions that highlight cognitive lapses may be deeply unsettling. The testing experience may thus not only challenge their cognitive ability but also their self-concept as respected elders in the community. Feelings of embarrassment, frustration, or loss of face could contribute to withdrawal or refusal to continue.^35,38

These suggest that cognitive testing among older Filipino adults must be conducted with heightened cultural sensitivity incorporating language, tone, and framing that affirm dignity and emphasize the social value of participation. Ensuring that participants feel respected and understood can help mitigate the perception that testing undermines their identity or self-worth.^35,38

Fear, institutional distrust, and diagnostic apprehension

The fear associated with clinical research was among the reasons for withdrawal. This could stem from the current political climate in the Philippines, wherein distrust among the government institutions was highly evident. A study reported a frequent suspicion regarding the motives of the study from potential research participants from a vulnerable population. While introducing the study and the researchers to the participants may help clear suspicions, it only aggravated their distrust. They introduced their study as a nationwide behavioral survey implemented by the Department of Health. However, awareness of the involvement of the government in the study was enough for the participants to withdraw. ³⁹ This distrust stemmed from the 2017 dengue vaccine controversy in the Philippines, which significantly affected public trust in vaccines, health system authorities, and medical science.^40,41 On the contrary, physician mistrust was not evidently observed during the recruitment. This contrast is well supported by the Institute for Health Metrics and Evaluation survey, which stated that the Philippines regarded health professionals as the most trustworthy organization and community leaders as the least trustworthy. ⁴² Since evidence has shown that health professionals are among the most trusted organizations, health promotion would benefit from community-based and healthcare-provider-led initiatives to rebuild public confidence in medical science. The government can strengthen policies on health promotion and education by designating the communication and implementation to community-trusted individuals, such as health professionals, barangay health workers, faith leaders, and respected local figures. This would reduce the politicization of health interventions and clearly separate scientific advice from political leadership. ⁴¹

Similarly, participants in the present study expressed apprehension toward dementia assessments, fearing not only the procedures themselves but also their possible implications. Being diagnosed with dementia is perceived as carrying a social label, one that implies potential burden to the family. ⁴³ Such fears are amplified by cultural expectations of self-reliance among older adults, where illness, especially one involving the mind, threatens both dignity and familial harmony. ⁴⁴ Hence, refusal to participate may function as something more than just avoidance; it represents a psychosocial defense mechanism aimed at preserving self-identity and protecting one's social standing within the family and community. ⁴³

Health-related limitations

Existing comorbidities or worsening health conditions

Existing comorbidities remain one of the most pervasive barriers to research participation among older adults. A systematic review identified exclusion criteria related to comorbidities as the most frequently cited reason for low recruitment rates in aging and dementia studies. ¹³ In the Philippine context, where multimorbidity is common, this challenge is particularly evident. Hypertension is the most prevalent condition among older adults (46%), followed by diabetes, angina, myocardial infarction, and renal disorders, collectively at 13%. Additionally, 18% report arthritis, while 17% have cataract. ²⁴ These overlapping conditions often require ongoing medical management, limiting the ability of potential participants to engage in long-term research activities. Even when older adults express willingness to participate, the presence of multiple chronic diseases can heighten concerns about fatigue, medication interactions, and study-related risks, leading either to exclusion during screening or voluntary withdrawal during follow-up.

Physical or cognitive inability to continue

Beyond chronic illness, the physical and cognitive challenges associated with aging can hinder sustained participation in research. As diseases progress, participants may experience increasing frailty, mobility limitations, or cognitive decline that impede their ability to comply with study procedures. ¹³ Dementia-related impairments, in particular, can affect comprehension, recall, and task adherence, requiring greater reliance on caregivers or legally authorized representatives for continued participation. ⁴⁵ In cases where caregiver support is limited or absent, attrition becomes more likely. Moreover, the psychosocial burden of illness, manifesting as exhaustion, anxiety, or frustration, can contribute to disengagement, especially when study visits require physical travel or repeated testing. ⁴⁶ These constraints illustrate how physiological deterioration intersects with social and logistical barriers.

Exclusion due to medical instability or progression of illness

Stringent exclusion criteria, while essential for scientific validity, can inadvertently perpetuate the underrepresentation of older adults in clinical research. ¹³ Many studies exclude individuals with unstable medical conditions or those taking medications that may influence study outcomes. ⁴⁷ In the present research, exclusions were limited to conditions and treatments that would directly confound results, such as structural or vascular causes of dementia, untreated psychiatric disorders, active uncontrolled gastrointestinal diseases, or major gastrointestinal surgery. Participants on systemic antibiotics, corticosteroids, immunosuppressants, or other medications known to alter gut or immune profiles were likewise excluded. Although these criteria were necessary for methodological rigor, they nonetheless reduced the eligible pool of participants. This selective inclusion highlights a persistent paradox in geriatric research: the population most burdened by illness is also the least likely to be represented in scientific evidence. ⁴⁸ Consequently, findings may not fully capture the clinical realities of older adults with complex health profiles.

Synthesis

These findings reveal that the barriers to recruitment and retention in dementia-related community studies are not discrete but interdependent, forming a complex web of family, economic, psychosocial, and health-related constraints. Family dynamics and economic pressures serve as foundational determinants that shape older adults’ capacity to participate. The unavailability of a LAR emerges as a critical intersection of these factors, rooted in the growing independence of older Filipinos and compounded by the judicial complexities of guardianship procedures. Even when potential LARs exist, competing family and work responsibilities restrict their availability. These conditions illustrate how caregiving obligations and economic constraints mutually reinforce one another, creating a structural barrier for research participation.

These familial and economic realities intersect with psychosocial and cultural mechanisms that further dissuade involvement. The normalization of dementia as a natural part of aging, coupled with cultural beliefs equating old age with wisdom and autonomy, generates ambivalence toward diagnosis and research participation. Admitting to cognitive decline challenges long-held notions of dangal (dignity) and social respectability, making refusal an act of self-preservation rather than indifference. Similarly, discomfort during cognitive assessments, perceived as infantilizing, exposes how cultural sensitivities around hiya (shame) and loss of status can directly shape withdrawal behaviors. These reactions are compounded by broader institutional distrust and diagnostic apprehension, wherein fears of stigmatization or government involvement heighten participants’ reluctance to engage.

Health-related exclusion both mirrors and reinforces the psychosocial and economic barriers faced by older adults. In the Philippine context, where multimorbidity is prevalent and often inadequately managed, chronic illnesses, along with progressing frailty, mobility limitations, and cognitive decline, further hinder participation, particularly in the absence of caregiver support. The financial strain of managing these conditions compounds the challenge through transportation costs and lost work hours. Psychosocially, illness fosters frustration and dependency, conflicting with cultural expectations of self-reliance among older Filipinos. Moreover, methodological exclusion criteria, although essential for scientific validity, exacerbate inequities by systematically omitting individuals with unstable or multiple conditions, thereby excluding those most affected by dementia.

Notably, while this study elucidates multiple intersecting barriers to participation, it did not systematically examine facilitators of research engagement or participants’ motivations for consent. Potential enabling factors, such as perceived benefits of health assessments, trust in local health workers, or interest generated through dementia education activities, were therefore not formally explored. As a result, the synthesis primarily reflects constraints rather than the full spectrum of influences shaping participation decisions.

Collectively, these economic, psychosocial, and health constraints form a cycle of disadvantage that limits equitable participation in AD research. Addressing this intersection requires culturally sensitive recruitment approaches, flexible study protocols, and supportive policies that mitigate both structural and emotional barriers to inclusion. Future investigations that integrate qualitative or mixed-methods approaches to capture both barriers and facilitators may provide a more balanced understanding of research engagement and inform more inclusive and effective community-based recruitment strategies.

Conclusion

This study highlights how recruitment and retention challenges in AD research manifest and intersect within community-based settings in the Philippines. Consistent with prior literature, caregiver dependence, health-related limitations, and stigma surrounding dementia emerged as key barriers; however, our findings demonstrate that these factors are deeply shaped by local family structures, economic constraints, cultural values surrounding dignity and aging, and institutional contexts.

The unavailability of LARs emerged as a central reason for both non-consent and attrition, shaped by caregiving obligations, work arrangements, and procedural barriers to guardianship. Psychosocial and cultural factors, including the normalization of cognitive decline, reluctance toward diagnostic labeling, and discomfort with aspects of cognitive assessment, also influenced participation decisions, while existing comorbidities and study exclusion criteria limited the inclusion of some individuals identified during community screening.

Together, these intersecting constraints reveal a cycle of disadvantage that restricts equitable participation in community-based AD research. Addressing this requires recruitment strategies that extend beyond access alone to incorporate culturally sensitive communication, flexible study procedures, and structural support for caregivers. Future research that integrates facilitators of participation alongside barriers may further inform inclusive and contextually appropriate approaches to dementia research in low- and middle-income settings.

Supplemental Material

sj-pdf-1-alr-10.1177_25424823261431318 - Supplemental material for Challenges in community-based recruitment of Alzheimer's disease cases: Experience of the monitoring drug efficacy through multi-omics research initiative in Alzheimer's disease (MEMORI-AD) study

Supplemental material, sj-pdf-1-alr-10.1177_25424823261431318 for Challenges in community-based recruitment of Alzheimer's disease cases: Experience of the monitoring drug efficacy through multi-omics research initiative in Alzheimer's disease (MEMORI-AD) study by Fresthel Monica M Climacosa, Eric David B Ornos, Erwin Rommel S Diwa, Mary Gale R Guantia, Almeera P Qureshi, Nicole Clarence Louise L Gapaz, Aira B Dacasin, Joannes Luke B Asis, Ajina C Carampel, Angelica M Dela Cruz, Francis James A Gordovez, John Carlo B Reyes, Ian Kim B Tabios, Rafael Vincent M Manalo, Joana Marie C Cruz and Veeda Michelle M Anlacan in Journal of Alzheimer's Disease Reports

Supplemental Material

sj-pdf-2-alr-10.1177_25424823261431318 - Supplemental material for Challenges in community-based recruitment of Alzheimer's disease cases: Experience of the monitoring drug efficacy through multi-omics research initiative in Alzheimer's disease (MEMORI-AD) study

Supplemental material, sj-pdf-2-alr-10.1177_25424823261431318 for Challenges in community-based recruitment of Alzheimer's disease cases: Experience of the monitoring drug efficacy through multi-omics research initiative in Alzheimer's disease (MEMORI-AD) study by Fresthel Monica M Climacosa, Eric David B Ornos, Erwin Rommel S Diwa, Mary Gale R Guantia, Almeera P Qureshi, Nicole Clarence Louise L Gapaz, Aira B Dacasin, Joannes Luke B Asis, Ajina C Carampel, Angelica M Dela Cruz, Francis James A Gordovez, John Carlo B Reyes, Ian Kim B Tabios, Rafael Vincent M Manalo, Joana Marie C Cruz and Veeda Michelle M Anlacan in Journal of Alzheimer's Disease Reports