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

Introduction Depression in late life is associated with significant morbidity, including deficits in a range of cognitive functions and considerable functional impairment and disability. The relationship between cognitive status and depressive symptoms and their effects on functional decline are of significant clinical and public health importance, because both are common, frequently coexist, and may be treatable. Neurocognitive deficit involving executive dysfunction is common when first onset of depression occurs in late life. A number of clinical factors might be linked to neuropsychological decline in late-onset depression. (1-3) Even after controlling for the effects of demographic variables, there is still an effect of depressive severity on cognitive function. The relationship between disability and depression is even more complex and probably bidirectional. In a systematic review of variables predicting functional decline in community-dwelling older adults, depression was one of the key risk factors identified. (4) Beekman et al (5) reported that both major and minor depression were associated with disability. Lyness et al (6) reported that functional outcomes associated with subsyndromal or minor depression were not as poor as for those among patients with major depression, but poorer than observed for those who were non-depressed. Previous studies of clinically non-demented community-dwelling Chinese elderly in Hong Kong found that executive dysfunction, depressive symptoms, apathy, and mild parkinsonian signs (MPS) were associated with functional disability. (7-9) However, information about the functional correlates in Chinese elderly with late-onset depression was limited. Chan et al (10,11) found that depressed Chinese elderly had poorer self-perceived quality of life and that quality of life correlated with the level of depression and functional limitations. It would be important to investigate how the severity of mood symptoms and physical health affects cognitive and functional performance in this group with significant mood disturbances. In the current cross-sectional study, we aimed to investigate the relationship between cognitive performance and severity of depression in Chinese elderly subjects with late-onset depression. The second aim was to examine the impact of cognitive function and mood symptoms on functional performance in depressed Chinese elderly. Investigating the relationship between these factors might provide insight into the underlying pathology of late-onset depression and help identify those at high risk and greater disability for further investigation. Methods Sample Patients aged [greater than or equal to] 60 years who fulfilled DSM-IV criteria (12) for major or minor depression were recruited from psychiatric outpatient clinics and the inpatient psychiatric unit in the New Territories East Cluster hospitals in Hong Kong from year 2007 to 2009. The onset of the first depressive episode had to be at the age of 50 years or older. Each depressed subject was evaluated by a qualified psychiatrist to establish eligibility for inclusion in the study, a clinical diagnosis, and a clinical staging assessment using the Clinical Dementia Rating (CDR) scale. (13) Subjects with a global CDR score of 0 or 0.5 were recruited. Subjects with a history of degenerative neurological disorder, dementia, cortical strokes, severe or unstable physical illness (i.e. those who had been hospitalised in the last 3 months), and a history or current substance/alcohol abuse were excluded. Subjects who had had electroconvulsive therapy in the past 3 months were also excluded. The psychiatrists explained the procedure and obtained written consent from the participants or their caregivers. This study was approved by the Joint CUHK-NTEC Clinical Research Ethics Committee. An experienced research assistant performed the cognitive and functional assessment. …