Cognitive and functional impairment in Chinese elderly with late-onset depression.

Introduction Given that the personal and public burdens of both depression and cognitive impairment are likely to increase along with the ageing population, it is important for mental health professionals to better understand the characteristics of cognitive impairment in depression, as well as how to detect and treat it. There is increasing recognition that cognitive impairment occurs in geriatric depression, and that its presentation is heterogeneous. Most research has found that depressed individuals tend to have worse performance relative to non-depressed comparison groups on a number of neuropsychological measures. The most consistent deficits occur in the areas of processing speed (1-3); effortful tasks involving selective attention, response inhibition, and performance monitoring (i.e. executive functions) (4,5); and the acquisition and retrieval of new information (i.e. episodic memory). (5) Neurocognitive deficits involving executive dysfunction are common when the episode of depression occurs in late life. Some research suggests that memory deficits may be more focally affected among older individuals with a history of recurrent depression beginning earlier in life. (6) Studies involving multiple cognitive domains found that 33 to 50% of depressed individuals have clinical levels of cognitive impairment. (7,8) The presence of depression (particularly in late-onset cases) should raise the possibility of screening for cognitive impairment as part of a long-term approach to care. Depression has considerable influence on functional impairment and disability. The relationship between disability and depression is 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. (9) Impairment in activities of daily living (ADL) is likely an underappreciated feature of depression and one that has important effects on dementia outcomes. Functional impairment may also be a marker for adverse outcomes. Among depressed individuals, self-reported impairments in instrumental activities of daily living (IADL) are associated with more pervasive cognitive impairment and persistence of impairment after depression remits. (10,11) Thus, evidence of functional impairment among individuals with depression may be a warning sign of individuals who are at risk for cognitive decline and that this risk may be lowered by effective identification and treatment. In Hong Kong, there is a paucity of studies on the cognitive and functional profiles of subjects with late-onset depression. Our study aimed to investigate cognitive and functional impairment in Chinese elderly subjects with late-onset depression. We hypothesised that such elderly had impairment in cognition and IADL compared with non-depressed age- and education-matched controls. The corresponding findings could provide more information to characterise the clinical presentation of late-onset depressive syndromes. Methods Sample Depressed Subjects Patients aged [greater than or equal to] 60 years who fulfilled the DSM-IV criteria (12) for major or minor depression were recruited from psychiatric outpatient clinics and the inpatient psychiatric unit. The onset of the first depressive episode was aged [greater than or equal to] 50 years. Each depressed subject was evaluated by a qualified psychiatrist to establish eligibility for inclusion in the study and a clinical diagnosis, and to assess clinical staging based on the Clinical Dementia Rating (CDR) scale. (13) Subjects with a global CDR score of 0 or 0.5 were recruited. Controls The control subjects were recruited from a population-based epidemiology study of cognitive impairment in elderly conducted from October 2005 to July 2006.14 The subjects had been assessed by an experienced psychiatrist and were neither clinically demented nor depressed. …