Risk factors for dementia, depression and psychosis in long-standing Parkinson's disease

Objectives. To study the relationships between clinical features of Parkins on's disease (PD) and the development of dementia, depression or psychosis in patients with long-standing disease. Background. The natural history of dementia and depression in PD, and its r elation to psychosis in long standing PD, are unclear. Method. 172 consecutive patients (99 men and 73 women, mean age at symptoms onset 58.3 +/- 13.2 years) with 5 years or more of PD (mean symptom durati on of 11.8 +/- 5.6 years) were studied. Clinical data were collected during the last office visit through physical examination, detailed history, revi ew of patient charts and outside documents. Dementia and depression were di agnosed according to DSM-IV criteria, while psychosis was diagnosed if hall ucinations or delusions were present. Chi-square and t tests were used to c ompare the patient characteristics among those with vs. those without menta l complications of the disease at different disease stages. Logistic regres sion was used for the comparison of associations between the presence of de mentia or depression (dependent variable) and age at onset of PD, duration of PD and disease staging (explanatory variables). Results. The study population consisted of 45 patients at Hoehn & Yahr (H&Y ) stage less than or equal to 2.5 (26%), 104 patients at stage 3 (60.5%) an d 23 patients at H&Y stage 4-5 (13.5%). Sixty one patients (36%) had dement ia, 55 patients had depression (33%) and 50 patients (27%) had psychosis. D ementia and depression were significantly associated with disease severity as reflected in the H&Y scale (P = 0.0003, Z = 3.59; P = 0.006, Z = 3.22, r espectively). These associations were significant also for the older age of PD onset (greater than or equal to 59 years n = 89) subgroup (p = 0.001, Z = 3.2 for dement-ia and p = 0.02, Z = 2.9 for depression), but not for you nger onset cases (<59 years n = 83). Dementia was significantly associated with older age of PD onset (beta = 0.04, p = 0.009) while depression was in versely associated with age of PD onset (beta -0.04, p = 0.02). The presenc e of dementia was also significantly associated with depression (beta = 1.4 9, p = 0.0006). Dementia and depression were found to be independent explan atory variables for the development of psychosis (logistic regression, odds ratio (OR) = 26.0, p < 0.0001; OR = 10.2, p < 0.0001, respectively). In pa tients with younger age of PD onset, depression more than dementia was stro ngly correlated with the appearance of psychosis. Conclusion. Dementia in PD was related to older age of symptoms onset and o ld age. Depression was associated with dementia or early age of PD onset. D epression seemed to contribute to the appearance of psychosis even more tha n dementia, especially in patients with younger age of symptoms onset.