Alzheimer’s Disease and the Elderly in Israel

Abstract

With the continuing rise in the elderly population, Alzheimer’s disease (AD) and dementia represent an increasing public health concern worldwide. In recent years, research has focused on the relationship between AD and ethnicity. Israel, a multiethnic society, provides a natural laboratory for research on ethnicity and health. The largest ethnic group is that of Israeli Jews, followed by Arab citizens, mostly Arab Muslims, with smaller numbers of Arab Christians in addition to Druze, Circassians, and others. The aim of this review is to clarify ethnic differences in prevalence and risk factors for Alzheimer’s disease. We review available literature on ethnic differences in epidemiologic and risk factors for Alzheimer’s disease, including genetic differences as well as disparities in health access and quality of health services. We will conclude with research and policy implications.

Introduction

The global prevalence of dementia, a syndrome characterized by progressive deterioration in cognition, function, and behavior, places a considerable burden on the society. Currently, the worldwide number of individuals with dementia is estimated to amount to 36 million and is predicted to triple by the year 2050, ¹ with Alzheimer’s disease (AD) being the most prevalent type of dementia.

In an effort to prepare for confronting the demands associated with these epidemiological changes, we are witnessing in the last years an increased attention to understanding the associations between AD and ethnicity. Examining ethnic differences in AD is important for etiological and psychosocial research as well as for service planning and intervention development. Studies conducted in different countries have reported ethnic differences in the incidence and prevalence of AD, in the biological and genetic basis of the disease, in the screening and diagnostic techniques used, in the services received by the person with AD and his or her caregivers, and in the knowledge and beliefs about AD. ²

Despite the proliferation of research on this topic in other societies, in Israel research on ethnicity and AD has attracted limited attention. This is surprising, especially since Israel is a multiethnic society, comprised of Israeli Jews, followed by mostly Arab Muslims, with smaller numbers of Arab Christians in addition to Druze, Circassians, and others. ³

Here, we review the available literature on ethnic differences in AD in Israel. The review will concentrate on studies examining differences between Israeli Jews and Arabs in epidemiologic and genetic aspects of AD, risk factors, disparities in health access, and health services as well as in knowledge and beliefs regarding AD. We will conclude with a discussion of the literature reviewed and the research, practice, and policy implications of the findings.

Prevalence of AD Among the Arab Population in Israel

Thus far, only a few epidemiological studies of dementia were conducted in Israel and have been limited to the Jewish population. ^4,5 Recently, several studies attempted to estimate the prevalence of AD in the Arab population. Bowirrat and colleagues, ⁶ using Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) criteria and a semistructured questionnaire, assessed a sample of 821 persons aged 60 and older residing in the rural area of Wadi Ara in the Northern part of Israel. Their findings showed that 20.5% of their sample was diagnosed with AD after controlling for age, gender, and education. This rate was almost 4 times higher than the prevalence reported by a study using similar methodology but conducted among Jewish persons aged 75 and older. ⁷ A high prevalence of cognitive impairment was also reported in another study assessing Arab inhabitants of the same geographical region aged 65 and older. ⁸ These authors found in a door-to-door study including 944 Arab participants that almost 10% had AD and 32.1% mild cognitive impairment (MCI). Differences in testing methods may be responsible for the variable results.

Genetic Aspects of AD Among the Arab Population in Israel

The high prevalence rates of AD reported by the studies conducted among the Arab population in Israel might be explained by genetic factors, especially since the disease shows heritability up to 79%. ⁹ Indeed, high rates of consanguineous marriages are reported between Israeli Arabs in general. ¹⁰ A similar finding was reported by Sherva and colleagues ¹¹ in a study conducted in the same area, although these authors found that there is less autozygosity in cases with dementia than in the comparison population.

Genetic studies conducted among the Arab population showed several interesting and puzzling findings. The first genetic analysis conducted among 256 participants of the original sample using a PCR-based method showed a lower frequency of the APOE ξ4 alleles than other caucasian populations. ¹² Further studies, using low-density genome scan of 375 microsatellite markers, identified regions on chromosomes 2, 9, 10, and 12 with significant linkage to AD status. ¹³ A strong association between AD and angiotensin-converting enzyme (ACE) gene polymorphisms has been reported in this population. ¹⁴ SORL1 is a protein implicated in the pathogenenis of AD and was discovered using, among others, genetic samples from the Israeli–Arab population. ¹⁵ Another study based on this population implicated additional AD risk genes in the retromer pathway. ¹⁶ The retromer complex is a conserved protein complex required for endosome-to-Golgi retrieval of a number of physiologically important membrane proteins including SORL1. ¹⁶ A recent genome-wide association study (GWAS) conducted scanning of 124 cases with AD and 142 cognitively normal controls and identified 220 single-nucleotide polymorphisms (SNPs) associated with AD. ¹¹ In that study, 8 autozygous regions on 7 different chromosomes were more frequent in controls than in cases with AD, and 116 SNPs in these regions, primarily on chromosomes 2, 6, and 9, were associated with AD. Besides, these autozygous regions, analysis of the full Wadi Ara GWAS data set, revealed 220 SNP associations with AD.

Risk Factors of AD Among the Arab Population in Israel

Besides the genetic risk factors described in the previous section, studies assessing the characteristics of AD among the Arab population in Israel examined some of the most commonly known demographic and environmental risk factors.

Sociodemographic Factors

The sociodemographic factors examined included age, gender, and education. Similar to studies in other populations, ¹⁷ advancing age and female gender were found to be important risk factors for AD among the Arab population in Israel. Indeed, the study conducted in the Wadi Ara sample showed that the prevalence of AD increased from 8% among individuals aged 60 to 69 to 51% among those aged older than 70. ^6,18 Regarding gender, results from the same study showed that while the prevalence rate of AD among men was 15%, among women it reached 25% (this difference was statistically significant at the P < .0005 level). The difference between the genders was even more impressive in the door-to-door study, with prevalence rate estimates among men being 5.2% and among women 14.2%, ⁸ with the contribution of gender to risk of AD remaining significant following control for education level.

The relative lower mean years of formal education that characterizes members of minority groups compared to the majority group along with their higher levels of illiteracy were strongly associated with AD in many studies assessing the effects of ethnicity in AD. ^2,19 Similarly, the few studies assessing AD among the Arab population in Israel found a strong association between education (assessed as number of school years) and prevalence rates of dementia and MCI. ^6,8,18,20 This association may be understood in the context of the relatively high rates of illiteracy among the Arab population in Israel, ²¹ which significantly affect the individual’s performance on neuropsychological assessments. ²² Since Mini-Mental State Examination norms are very low in Arab women with no formal education, ²³ the use of these tests may generate diagnostic bias, especially among women. One study based on clinical diagnosis of AD, rather than neuropsychological assessment, showed that the increased risk of AD due to lower education is beyond that of older age and female gender. ⁸ However, the association between literacy and cognitive functioning among the Israeli Arab population could be more complex, as suggested in a study examining differences in cognitive functioning between Israeli Jews and Israeli Arabs, ²⁴ in which different aspects of cognitive functioning (subjective reading, subjective writing, time orientation, arithmetic, verbal learning, verbal recall, and word fluency) were assessed among a national representative sample. Surprisingly, results of this study showed that Israeli Arabs performed significantly better on the verbal recall task than the other groups. The authors suggest that this might be the result of the well-developed oral tradition among Arabs, an explanation hinting that the relationship between literacy and cognitive functioning among minorities needs further examination.

Health and Health Behavior Factors

Certain health conditions and health behaviors appear to increase the risk of dementia in general and AD in particular. Specifically, cardiovascular risk factors (such as smoking, obesity, diabetes, and hypertension) are associated with increased AD risk. ¹⁷ Conversely, other factors such as physical activity, social and cognitive engagement, and a diet rich in vegetables and vegetable-based oils were found to be protective factors associated with reduced risk of AD and dementia. ¹⁷

The effects of some of these risk and protective factors were examined in the studies assessing AD in the Arab population in Israel. Similar to findings from other studies, a strong association was found between hypertension and AD among Israeli Arabs, with high blood pressure being a significant risk factor for AD independent of age and education. ²⁰ Although these findings may relate to the reported association with ACE gene polymorphisms and AD, ¹⁴ it could also be hypothesized that the association with hypertension among members of the Arab population is related to the limited involvement in health-promoting behaviors (such as physical activity) that have been documented in this population. ²¹ Although the importance of facilitating health-promoting behaviors for AD among members of minority groups has been repeatedly documented in the literature, the studies conducted in Israel among members of the Arab population have only superficially investigated this topic.

Regarding smoking, no significant difference has been observed in the prevalence of AD between smokers and nonsmokers, ⁶ although it should be noted that unlike other studies examining the topic ²⁵ in the Israeli study, this association was examined only among men due to the low rates of smoking among Arab women.

Finally, among the myriad of leisure activities reported to be associated with the risk of dementia ²⁶ and despite the fact that many of them were also assessed in the Arab population in Israel, we found only 1 published study reporting on this topic. Inzelberg and colleagues ²⁷ evaluated the relationship between midlife praying (defined as practicing prayer rituals without taking into account spirituality or religiosity) and cognitive decline among 935 elderly persons in Wadi Ara and found that among women, midlife praying between the ages of 20 and 60 was associated with a reduced risk of AD. ²⁷

Cultural and Cognitive Factors

There is ample evidence that knowledge, perceptions, and beliefs provide meaning to the experience of illnesses and affect health-promoting behaviors such as help seeking, adherence to treatment, and reduced stigma, among others. ²⁸ Accordingly, the attention paid to the understanding of how cultural values and beliefs shape the meaning that different ethnic groups assign to dementia is steadily increasing worldwide. ²⁹ Surprisingly, however, only a limited number of studies have explored these issues within the Israeli Arab population.

Lay persons’ knowledge, perceptions, and beliefs about AD

Examining the knowledge about dementia regarding its prevalence, symptoms, prevention, and treatment is important because it can guide the identification of areas of misinformation and the development of intervention programs aimed at improving appropriate areas.

To the best of our knowledge, no study to date has been published about the knowledge on the disease among members of the Israeli Arab population. Yet, findings from an ongoing study assessing knowledge about symptoms of dementia in a representative sample of 989 Israeli adults showed that Jewish participants were more likely than Arab participants to correctly identify symptoms of AD. These differences were statistically significant for items reflecting secondary symptoms of the disease such as social isolation, mean (standard deviation [SD]) = 2.7 (1.6) and 3.1 (1.6), in Jewish and Arab participants, respectively, as well as for items reflecting the main symptoms of AD such as inability to remember simple words, mean (SD) = 3.3 (1.5) and 2.8 (1.5) in Jewish and Arab participants, respectively, and having difficulty performing simple math calculations, mean (SD) = 3.3 (1.5) and 2.7 (1.5) in Jewish and Arab participants, respectively (Unpublished).

Regarding perceptions and beliefs of AD, Werner, ³⁰ in a quantitative study including a convenience sample of 186 Israeli Jewish and Arab adults (mean age = 64.1; SD = 7.7) with no family history of AD, found that Israeli Arabs expressed less worries about memory problems than Israeli Jews. This finding was corroborated in a later study including a representative sample of the Israeli population aged 18 and older. ³¹ The explanation for these low concern levels might lie in the positive emotional reactions reported by Israeli Arabs toward a person with AD. Indeed, in a study including 170 Israeli Arab participants aged 40 to 85, the majority reported high levels of positive emotions toward a person with AD, such as sympathy (91%), compassion (90%), and desire to help (88%), and only low percentages of participants reported negative feelings such as uneasiness (27%), rejection (14%), and embarrassment (12%). ³²

Different results (probably due to different methodologies used) were found in a study assessing stigmatic beliefs in a nationally representative sample of the Israeli population aged 18 and older. Using a vignette methodology, a computerized phone interview was conducted with a sample of 989 adults (83% Jewish and 27% Arab; mean age 46.5). Participants were asked to report their stigma beliefs toward a person with AD. Compared to Jewish participants, Arab participants reported more frequent negative feelings (anger and fear) and less frequent positive feelings (willingness to help) toward the person with AD described in the vignette. Additionally, they perceived the person in the vignette to be more dangerous and more responsible for his situation than Jewish participants and reported higher levels of segregation and coercion compared to Jewish participants. ³³

Caregivers’ perceptions and experiences

We were able to find 2 published studies examining caregivers’ perceptions and experiences among the Israeli Arab population. Lowenstein, ³⁴ in a study including 64 Jewish and 50 Arab caregivers of persons with dementia, found that, independent of the cognitive status of the diseased person, Arab caregivers perceived their physical and mental health better than the Jewish caregivers. This difference might be attributed to the unique values shared by the Arab population including communitarian concepts, collective consciousness, solidarity, mutual concern, and interdependence as emerged in a qualitative study conducted with 18 Arab caregivers of patients with AD living in rural communities in the Northern part of Israel. ³⁵

Summary, Conclusions, and Research Recommendations

Estimates indicate that the Israeli Arab population is rapidly growing which suggests a corresponding increase in the number of persons with dementia among members of this group. ³ The relatively high prevalence of MCI in this population also predicts patients with AD to be added each year. ⁸

After examining the literature in this area, we conclude that the topic of AD—its epidemiological, clinical, and societal characteristics—among the Arab population in Israel remains an understudied and poorly understood topic. In fact, a majority of publications assessing the genetic and clinical aspects of the disease were based on 2 studies conducted in the same geographic area—Wadi Ara, which includes mainly Muslim residents. No other studies, we know of, have examined risk and protective factors for dementia among other subgroups of the Israeli Arab population. Although studying genetically homogeneous populations with high prevalence of AD has important scientific value, more extensive data gathering, including also ethnicity-related life style measures (such as diet, physical activity, and obesity), might enrich our knowledge in this area and guide the development of evidence-based, culturally competent interventions. This is especially important since several studies have documented the low adherence to health-promoting behaviors among Israeli Arabs. ^36,37 Moreover, despite their importance, both Israeli studies are limited as they lack neuropathological information. Due to religious restrictions, postmortem examinations are extremely rare among both Jews and Muslims in Israel.

Despite their limitations, several clear and consistent conclusions emerged from our literature review. First, the prevalence of AD among members of the Arab population in Israel is relatively high and even higher than in societies with a similar profile of education and literacy such as India, Taiwan, Egypt, and other countries. Second, as could be expected and in concurrence with many studies worldwide, older age, female gender, and lower education were significantly associated with dementia. ¹ Third, these studies showed that even in a homogeneous population as the Arab population in the Northern villages of Israel, AD is a multifactorial disorder influenced by numerous genes and sociodemographic factors.

But not only genetic and epidemiological studies about AD in the Israeli Arab population are few. Also, research assessing knowledge, beliefs, and perceptions about the disease in this sector is scarce. This is surprising, especially since studies in other minority groups showed that low levels of knowledge, different beliefs, and attitudes as well as increased stigmatic beliefs and feelings of shame delay their access to services and their help-seeking patterns. ^38,39

The few studies conducted in Israel corroborate these patterns among the Israeli Arab minority. Indeed, compared to the Jewish population, low levels of objective and perceived knowledge were found, stressing the importance of developing educational programs, specially geared to increase knowledge and awareness in this population.

Similar to findings reported for other mental illnesses, ⁴⁰ increased levels of stigmatic beliefs were found among the Arab population in Israel. These findings suggest the need to develop campaigns to combat the stigma associated with AD which are especially tailored to the needs of ethnic minorities.

Finally, there is also a dearth of research assessing caregivers’ perceptions and experiences within the Arab population. The 2 articles published on the topic agreed that this population’s unique cultural values might explain the feelings of burden and depression experienced by family members caring for a person with AD. Indeed, a study assessing depression among a group of 250 randomly sampled Arab adult children caregivers showed that filial piety (defined as the practice of familial respect of and care for the parents) was a central variable in the relationship between caregiver burden and depression. ⁴¹ However, this article did not specifically examined caregivers of persons with AD.

As we conclude, we note that there is more left to do than what has been done. Given the expected increase in the number of persons with AD in general and among the Israeli–Arab population in particular, there is an urgent need to expand research particularly in the following areas:

Epidemiological Research

• Prevalence studies based on a better neuropathological confirmation of the diagnosis should be encouraged in order to overcome the suspicion that diagnoses are not culturally biased. ¹⁹

• Longitudinal studies aimed at assessing contextual factors across ethnic groups along the life course should be developed.

• Research should address possible differences among subgroups within the Arab population in Israel (eg, Christian Arab and Druze).

Risk Factors Research

• Studies assessing a wider variety of risk factors (such as comorbidity, diet patterns, obesity, and more) should be conducted as the knowledge in this area expands. ²⁵

• The conclusions of such studies may enable prevention programs that may reduce prevalence of dementia.

Clinical Studies

• There is an increasing need to develop studies aimed at assessing the recognition and management of dementia in primary care in the Arab population.

• An examination of the characteristics of dementia-related behavioral problems and their treatment in the Arab population is warranted.

Knowledge, Perceptions, and Beliefs Research

• The study of ethnic differences in the perceptions and beliefs regarding AD should be expanded and examined using large representative samples that will allow more powerful analyses to disentangle the effects of ethnicity and socioeconomic status on stigma findings.

• Studies of Arab caregivers for persons with dementia should be encouraged. Special attention should be given to theoretically driven studies that will allow examining differences in the levels of stress and burden experienced by different groups together with an understanding of the process leading to these differences.

• The use of qualitative methods to elucidate the unique ethnic and cultural values and norms involved in the caring for a person with AD should be increased.

Help Seeking and Utilization of Health Services

An examination of the differences in help-seeking patterns and treatment preferences is required.

The issue of differential utilization of dementia health care services by the Arab population should be examined. This is especially important as previous studies in other countries have reported ethnic differences in the use of dementia treatment services, ³⁸ and studies conducted in Israel have shown inequalities in the use of health services among Jews and Arabs ⁴² in general and in the use of mental health services in particular. ⁴³

In sum, the answer to the question posed in this review is no. Not enough attention has been devoted to the field of dementia in the Israeli–Arab population, and knowledge in this topic is still in its developing stages. This should not discourage us, however, and since AD is a serious problem, something must be done. Appropriate funds should be allocated to increase research efforts in this area to attain a better understanding of the phenomenon. Public policy steps should be taken, such as increasing the efforts in rising awareness and knowledge, developing and evaluating education and intervention campaigns geared specifically to the needs of the Arab population, and mobilizing decision makers and lay persons to prioritize AD issues in this group. Only such steps will provide persons with AD and their caregivers in the Arab population with better care and quality of life.