Abstract
Introduction
Recent findings documented the important role of purpose in life in older adults, that represents the feeling that one’s life is goal-oriented and worthwhile (Sutin et al., 2024a, 2024b). Considered as a core ingredient of psychological well-being (Ryff, 1989), purpose in life has been linked with healthy aging, a buffering effect on chronic illnesses and on cognitive deterioration and even with lower mortality (Koga et al., 2024; Sutin et al., 2024a, 2024b).
Sutin et al. (2024a, 2024b) documented that purpose in life was associated with a better motor function, represented by a lower risk of falling, the maintenance of physical activity and of engagement in daily activities across older adulthood. These studies included older adults who were evaluated also in terms of physical activity and disease burden, conceived as the sum of seven reported physician-diagnosed chronic diseases: hypertension, diabetes, cancer, lung disease, heart disease, stroke, and arthritis.
Another longitudinal study evaluated purpose in life, motor decline and progressive parkinsonism in 2,252 older adults (Koga et al., 2024). Authors considered health conditions as one of the potential confounders since they could affect both sense of purpose and parkinsonism. Purpose in life was associated with lower risk of incident parkinsonism and lower levels of parkinsonian signs at baseline and could contribute to the maintenance of healthy physical function among older adults. However, even though associations were observed after controlling for a wide range of covariates, authors have decided to exclude patients reporting to use Parkinson’s disease medication and suffering from Parkinson’s disease at baseline. Similarly, Sutin et al. (2024a, 2024b) did not include neurodegenerative conditions, in which purpose in life, walking speed and motor function could be significantly hampered and, at the same time, they represent important protective factors (Vescovelli, 2018).
To the best of our knowledge and differently from the previously reported studies, purpose in life has not been investigated specifically in patients with Parkinson’s disease (PD), whose motor function is the core symptom.
Thus, the aim of this study is to investigate the possible protective role of purpose in life for motor function and mental health of patients with PD. In particular, we will explore the associations among purpose in life, quality of life, well-being, psychological distress and motor function. We will also compare patients reporting higher versus lower levels of purpose in life controlling for socio-demographic and clinical variables.
We hypothesize that a higher purpose in life will be associated with higher quality of life, well-being, better motor function and with lower distress also in PD.
Methods
Participants and Procedure
The sample consisted of 59 consecutive patients with PD. Details of the recruitment method and study protocol have been described in detail elsewhere (Vescovelli, 2018).
Patients were voluntarily enrolled in the study and gave their written consent to participate. The rehabilitation clinic’s Ethical Commission (Rimini, Italy) approved the research.
In the original larger study, patients underwent an extensive medical evaluation in which they were evaluated according to the Unified Parkinson Disease Rating Scales, Hohen and Yahr scales and Mini Mental State Examination, administered by a physician. UPDRS resulted to be significantly correlated to Parkinson’s Disease Questionnaire 39 items (PDQ39; Jenkinson et al., 1997; Vescovelli, 2018).Of the 59 patients asked, 59 (100%) agreed to participate and returned completed questionnaires.
Their ages ranged from 52 to 84 years, with a mean age of 70.80 (SD = 7.41). Seventy-three percent (n = 43) were men and 27% were female (n = 16). They received a diagnosis of PD from 1 to 20 years earlier (Mage = 6.49 years; SD = 5.07). Seventy-five percent (n = 44) of the participants were married and 25% (n = 15) were unmarried (separated, divorced, widowed, or cohabitants). Most of them was treated with dopamine medication (for details see Table 1).
Socio Demographic and Clinical Characteristics and Differences Between HPIL and LPIL.
Note. HPIL = high purpose in life individuals; LPIL = low purpose in life individuals.
Measures
Well-Being
The Purpose in Life subscale (PIL) of the Psychological Well-Being Scales (PWB) (Ryff, 1989) is composed of seven items “e.g., Some people wander aimlessly through life, but I am not one of them.” Participants respond with a six-point format ranging from “strongly disagree” to “strongly agree.” This scale has satisfactory test–retest reliability. In the present study, the α was = .667.
The Quality of life scale (QoL) was measured with the single item: “How would you rate your quality of life” with a Likert scale from 4 “excellent” to 0 “very poor”. It was derived from the Psychosocial Index (Sonino & Fava, 1998) and it has been largely applied in many clinical and medical settings (Sonino & Fava, 1998).
The Personal Well-being Index (PWI) (International Wellbeing Group, 2013) investigates patients’ well-being by asking them “How satisfied are you with your life as a whole?.” Answers may range from 1 (completely dissatisfied) to 10 (completely satisfied).
Mental Health
The Symptom Questionnaire (SQ) (Kellner, 1987) is a 92-item self-rating questionnaire composed of four scales (anxiety, depression, somatization, and hostility-irritability). The SQ has been found to be a sensitive instrument to detect changes in clinical settings. Cronbach’s alpha indicators are as follows: SQ anxiety = .658, SQ depression = .549, SQ somatic symptoms = .709, SQ anger-hostility = .773.
The subscale of Mental Health taken from the Parkinson’s Disease Questionnaire 39 items (PDQ39; Jenkinson et al., 1997) is composed of six items exploring the presence of depressive, anxious, loneliness, isolation, anger, and worry symptoms. In the present study, Cronbach’s alpha for the PDQ39 mental health scale was = .855.
Motor Function
The Short Physical Performance Battery (SPPB) (Guralnik et al., 1994) is an objective assessment tool that combines the results of the walking speed, chair stand, and motor balance tests. It has been used as a predictive tool for disability and can measure the motor function in older adults. A physiatrist administered this tool to the sample at the intake.
Statistics
Bivariate correlations between purpose in life, well-being, distress indicators, motor function, and dopamine medication were analyzed using Pearson’s r coefficients.
The median value of purpose in life total score (median = 28) was calculated and used for dividing the whole sample into two groups: (1) High purpose in life individuals—HPIL—whose score was ≥28; (2) Low purpose in life individuals—LPIL—whose score was <28.
Chi square and Anova-Analysis of Variance were used to compare HPIL and LPIL with regard to group assignment and socio-demographic and clinical variables. Between-group comparisons on QoL, PWI, SQ, PDQ39 mental health scale and SPPB were conducted using the Analysis of Variance for each questionnaire, with the group belonging as a fixed factor.
All analyses were performed using the Statistical Package for the Social Sciences (SPSS) Windows Software Version 29.0.
Results
Correlations are displayed in Table 2. PIL was significantly and positively correlated to QoL (r = .365), PWI (r = .486) and to SPPB (r = .330). PIL was negatively related to SQ anxiety (r = −.393), SQ depression (r = −.599), and to PDQ39 mental health scale (r = −.255). SPPB was positively associated with dopamine medication (r = .256).
Correlations Among PIL and Well-Being and Distress Indicators.
Note. PIL = purpose in life scale of psychological well-being scales; QoL = quality of life scale; SQ = symptom questionnaire; PDQ39 = Parkinson’s disease questionnaire 39—mental health; SPPB = short physical performance battery.
p < .05. **p < .01.
Differences between HPIL and LPIL are displayed in Table 1. Using the median value of PIL subscale (median x̃ = 28), the whole sample of patients with PD was divided into two groups: (1) High purpose in life individuals—HPIL (n = 23, 39%)—whose score was ≥28; (2) Low purpose in life individuals—LPIL—whose score was <28 (n = 36, 61%). Thus, most patients with PD resulted to be in the second group.
As reported in Table 1, no significant differences emerged between the two groups in socio-demographic (age, gender, marital status) and in clinical (medication dopamine dosage and years from diagnosis) variables.
At the univariate test, HPIL individuals reported significantly higher scores in QoL (F1,57 = 4.420, p = .040) and in PWI (F1,57 = 13.426, p < .001), when compared to LPIL (Table 3).
Differences Between HPIL and LPIL in SPPB, QoL, PWBI, SQ, and PDQ39.
Note. HPIL = high purpose in life individuals; LPIL = low purpose in life individuals; QoL = quality of life scale; SQ = symptom questionnaire; PDQ39 = Parkinson’s disease questionnaire 39—mental health; SPPB = short physical performance battery.
p < .05. **p < .01.
Regarding SQ, HPIL reported significant lower scores in anxiety and depression (F1,57 = 6.817, p = .012; F1,57 = 20.658, p < .001, respectively—multivariate main effect for group: Wilks’ λ = .697, F4,54 = 5.882, p < .001, partial eta squared = 0.303) (Table 3).
Regarding PDQ39 mental health scale, HPIL reported significant lower scores (F = 3.848, p = .055), when compared to LPIL (Table 3).
Discussion
As expected, the protective role of purpose in life for motor function and mental health was confirmed also in patients with Parkinson’s disease.
Our results documented the presence of significant correlations among purpose in life, well-being, quality of life, symptomatology and motor function in the total sample of patients. Motor function, that was measured in terms of walking speed, chair stand, and motor balance, was found to be positively associated with the medication dosage: those who took higher dosage of dopamine have exhibited a better motor performance. However, dopamine dosage was not significantly correlated to purpose in life in this sample and did not differ significantly between HPIL versus LPIL (Table 1).
A first observation pertains to the fact that only a minority of patients (39%) was categorized into the HPIL group (with PIL scores higher than the median value of 28). When compared with the rest of the sample (61% of patients with PIL scores below the median value), they reported lower levels of anxiety and depression and greater well-being and a better quality of life and motor function.
Worth to be noted, high purpose in life was found to be a protective factor for motor function regardless of socio-demographic (age, gender, and marital status) and clinical (years from diagnosis and dopamine dosage levels) variables (Table 1). Given the cross-sectional design of the study, the relationships among these variables could also be interpreted in the opposite way: patients who show preserved/better motor function tend to be more active and to participate to social activities and this give them life purpose and meaning, by preserving their perceived quality of life and psychological distress.
These findings, even though preliminary, have partially compensated the shortage of studies on purpose in life in PD and have added information on its role for preserving motor function in such a disabling neurodegenerative condition (Vescovelli, 2018).
Differently from Sutin et al. (2024a, 2024b) and Koga et al. (2024), we have included a sample of patients in which motor function is the core clinical characteristic of their disease. Similarly, we did control for socio-demographic and clinical variables and still purpose in life did emerge as a protective factor for mental health and motor function.
The dimension of purpose in life is receiving increasing attention: recent studies have documented the significant association between purpose in life, self-rated health, and longevity/mortality in large US samples of older adults (Friedman & Teas, 2023).
Taken together, all these studies highlighted that purpose in life represents a crucial ingredient for counterbalancing the negative consequences of the aging process both in healthy and clinical populations (Friedman & Teas, 2023; Koga et al., 2024; Sutin et al., 2024a, 2024b).
In conclusion, the present study adds innovations to existing literature because for the first-time purpose in life has been explored in relation to well-being and distress after controlling for socio-demographic and clinical variables in a sample of patients with Parkinson.
The study has limitations, such as its cross-sectional design that did not permit distinction between cause and effect. Another limitation was represented by the small and self-selected and quite homogenous sample. In fact, patients devoid of cognitive deterioration and depressive symptoms were excluded (as reported in previous studies). Future studies with more heterogenous patients and larger sample could allow to better observe potential similarities or discrepancies between subsamples of patients with different clinical characteristics and in different illness stage (early vs. late stage). This could be achieved also by integrating a follow-up assessment, that now is lacking. If added, it could help to understand possible changes in our variables along time and different illness stages. Moreover, the study included self-rated instruments only, except for SPPB. Furthermore, for investigating quality of life we did include a scale that was not specifically used for aging individuals. A future investigation should better capture patients’ quality of life, by using a tool for the specific age group.
Finally, we did perform the physical assessment with a physiatrist, but we were not able to include an electronic device for monitoring patients’ movements and health-related variables continuously during the day. This type of tool could have provided more reliable data on motor function and patients’ lifestyle. Thus, our results need to be replicated with larger samples and with other psychometric and electronic assessment devices.
Future study with larger samples could help also to observe whether the role of purpose in life and well-being could vary according to the presence of different medical conditions (e.g., other neurodegenerative diseases, oncological, etc.) and to observe the possible correlations and discrepancies between purpose in life and other psychological dimensions (e.g., quality of life and distress) in patients suffering from different illnesses or healthy aging individuals.
Considering the importance of promoting purpose in life, psychosocial interventions tailored for enhancing this dimension could be crucial for older adults and for the treatment of patients with PD when this dimension appears to be impaired.
Future research is needed for testing their feasibility.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
