Older people with Parkinson’s disorder display more cognitive or cerebral decline over time in comparison with younger and less depressed people with PD in the cognitive ability spheres of speech and working memory/awareness.

To evaluate the longitudinal link between depressive symptoms and cognitive decline with ageing among patients with Parkinson’s disease (PD). This study was based on the idea that aged PD patients with more acute symptoms of depression would be at a higher risk of cognitive impairment compared to young people with PD.

All in all, 487 newly diagnosed people with PD were assessed for cognition changes and depression over a period of 5 years. The responsiveness, memory, learning, visuospatial ability, processing speed, and verbal functioning were assessed with the help of neuropsychological evaluation tests. The longitudinal link between cognition, age and depressive symptoms was examined with the help of multilevel modeling.

There was a noteworthy three-way interaction (Occasion x Age x Symptoms of depression) envisaging language and working memory/attention functioning. Particularly, the negative association of depressive symptoms with cognitive impairment in these spheres were more noticeable among the elderly. 

As compared to younger people, geriatric PD patients with comorbid depressive symptoms have more cognitive decline. Elders with PD may be more prone to neurotoxic consequences of depression (for example, inflammation of the nervous tissue, Hypothalamic-Pituitary-Adrenal Axis disruption). Therefore, better management of depression could lower cognitive decline and the risk of dementia (loss of cognitive functioning).