Cognitive function, functional performance and severity of depression in Chinese older persons with late-onset...

OBJECTIVES. The relationship between cognitive status and depressive symptoms and their liability to cause functional decline are of clinical and public health importance as it appears to be common, frequently coexists, and may be treatable. This study examined the relationship of depression severity and cognitive performance and the impact of such an interaction on functional ability in Chinese elderly subjects with late-onset depression. METHODS. A total of 105 non-demented elderly patients with late-onset depression were recruited. Impairment in instrumental activities of daily living and severity of depression were respectively assessed with the Disability Assessment for Dementia scale and the 24-item Hamilton Depression Rating Scale. Various cognitive domains were assessed including global cognitive function, delayed episodic memory, and executive functions. The relationship between specific cognitive impairment and mood symptom severity was assessed. The clinical correlates of functional performance were also examined. RESULTS. Increasingly severe depression was associated with lower scores in the Mini-Mental State Examination, delayed recall, and poorer performance in the Trail Making Test-Part A (after adjusting for the effect of age and education). The severity of apathy correlated negatively with the Mini-Mental State Examination scores only. Among the depressed subjects, greater levels of depression and apathy, poorer performance in Trail Making Test-Part B, and mild parkinsonian signs were associated with lower functional scores. CONCLUSIONS. Lack of interest and motivation, depressive mood, compounded by behavioural abnormalities resulting from executive dysfunction, accounted for functional disability in elderly subjects with late-onset depression. These relationships may provide the background for developing interventions targeting functional deficits associated with specific cognitive dysfunctions and depression.