Background: Depression and cognitive impairment in later-life have great bearings on public health. The two conditions often co-occur and have mutual implications on short-term risk and long-term prognosis.
Method: A two-phase epidemiologic survey on the prevalence of dementia in elders aged 60 and over was conducted in Hong Kong in 2005-2006. In the first phase, 6,100 randomly selected community dwelling elders were assessed with Cantonese version of Mini-Mental State Examination (C-MMSE) and Abbreviated Memory Inventory for Chinese (AMIC). Two thousand and seventy-three subjects were screened positive and invited for second phase cognitive and psychiatric assessment. 35.5% of screen-positive subjects participated in Phase 2 assessment conducted by psychiatrists for diagnosis of dementia. Severity of dementia was determined using Clinical Dementia Rating Scale (CDR). Cornell Scale for Depression in Dementia (CSDD) and a structured bedside cognitive battery were also administered to each subject.
Results: 1.7% of subjects with CDR 0.5 and 5.9% of subjects with CDR 1 had clinically significant depressive symptoms (>or= 8 on CSDD). Score on CSDD correlated positively with duration of cognitive symptoms, scores on CIRS and CMMSE in linear regression model. In a logistic regression model, male gender, duration of cognitive symptoms, CIRS and CMMSE was associated with increased risk for clinically significant depressive symptoms.
Conclusions: In our sample, milder forms of cognitive impairment were associated with increased risk for depression in the presence of other risk factors such as male gender, higher physical illness burden and longer duration of cognitive symptoms.