Influence of depression in mild Parkinson's disease on longitudinal motor and cognitive function

Studies have suggested a relationship between non-motor symptoms with motor fluctuations in patients with Parkinson's disease (PD). We studied the influence of depression on longitudinal motor and cognitive function among mild PD patients.

A 1.5 years longitudinal study of 102 patients with mild idiopathic PD. Patients were assessed with a standardized clinical assessment battery including motor and non-motor scales. Patients also underwent serial neurocognitive testing that assessed global cognition, memory, attention, language, visuospatial and executive function.

81 patients with mean age of 64.9(SD = 7.9) years and mean Hoehn & Yahr of 1.9(SD = 0.4) completed baseline and follow-up visits. 22 patients had clinically significant depression at baseline with mean Geriatric Depression Scale of 6.9(SD = 2.4). These patients presented with concomitant apathy and anxiety and were more likely to be females with longer duration of PD. At baseline, patients with depression had poorer performance on global cognition and all cognitive domains although not significantly different from patients without depression. At follow-up, there was no statistically significant difference on cognitive performance between those with and without baseline depression. Patients with baseline depression demonstrated worsening of motor function after 18 months (UPDRS Motor Score Change: +5.0[7.0]vs.+0.2[7.3]; p = 0.015). On multivariate analysis Baseline Motor Score (B = -0.229,CI = -0.445 to-0.013,p = 0.038), Baseline GDS (B = 0.622,CI = 0.078 to 1.166,p = 0.026) and PD duration (B = 0.520,CI = 0.105 to 0.935,p = 0.015) independently predicted increase in UPDRS Motor Score.

The findings suggest a relationship between early depression with motor worsening and cognition decline in PD patients. Further biomarker-supported studies investigating the role of depression on motor and cognitive function are needed.