Why do some patients adhere worse? The role of frailty and depression in Parkinson disease.

OBJECTIVE: To investigate associations of frailty, depression, disease severity, and sociodemographic factors with treatment adherence, health behaviours, and disease-related knowledge in patients with Parkinson disease (PD), and to examine the relationship between health behaviours and quality of life. METHODS: The study included 99 patients with PD (mean age: 70.11 ± 5.5 years; mean disease duration: 8.3 ± 5.68 years), all classified as Hoehn and Yahr stage 2 or higher. Standardized assessment tools included the Parkinson Disease Questionnaire (PDQ-39), Schwab and England Activities of Daily Living Scale (SE-ADL), Beck Depression Inventory (BDI), Adherence to Refills and Medications Scale (ARMS), Tilburg Frailty Indicator (TFI), Unified Parkinson Disease Rating Scale (UPDRS), Health Behaviour Inventory (HBI), and an author-designed clinical and sociodemographic questionnaire. RESULTS: Frailty was identified in 86.37% of participants. Non-frail patients demonstrated significantly better health behaviours (89.38 ± 8.25 vs 82.58 ± 10.16, p < 0.05) and treatment adherence (15.62 ± 2.18 vs 18.64 ± 4.08, p < 0.05) than frail patients. Better functional status was associated with higher treatment adherence (p < 0.001, ρ=-0.402), whereas greater severity of depressive symptoms was associated with poorer adherence (p < 0.001, ρ=0.352). Older patients were less likely to use the Internet to obtain information about PD (77.42% for 65 y.o, 41.94% for 66-70 y.o. and 24.32% for >70 y.o. group, p < 0.001), while higher educational attainment was positively associated with expanding knowledge about the disease (from 97.14% for higher education to 50% for primary, p = 0.001). CONCLUSIONS: Frailty, depressive symptoms, disease severity, and sociodemographic factors were associated with treatment adherence and health behaviours in patients with PD. Non-frail patients showed better adherence and healthier behaviours, while greater depressive symptom severity was associated with poorer adherence. PRACTICE IMPLICATIONS: Comprehensive PD care should address psychosocial, emotional, and behavioural factors alongside neurological management to support treatment adherence and patient care.