Influence of Depression on Working Memory Measured by Digit Backward Span in the Subjects with Mild Cognitive Impairment and Dementia

ABSTRACT

OBJECTIVES: We aimed to explore the influence of depression on working memory in patients with mild cognitive impairment (MCI) and dementia. METHODS: Clinical and neuropsychological data of 43 subjects with mild cognitive impairment (MCI) (n=17) and dementia (n=26) who had visited Department of Psychiatry at Soonchunhyang University Seoul Hospital, were collected. The subjects were divided into depressed (n=18) and non-depressed (n=25) groups based on the Korean version of Short Geriatric Depression Scale. Two-way analysis of variance test was conducted to evaluate the influence of diagnosis (MCI and dementia), the presence of depression and their interaction on working memory which was measured by digit forward and backward span test. RESULTS: Among the patients with MCI, test score of digit backward span test in depressed group was significantly lower than in non-depressed group. However, among the patients with dementia, there was no significant difference in digit backward span test between depressed and non-depressed groups. CONCLUSION: This study suggests that the depression could deteriorate working memory measured by digit backward span test in patients with MCI, relative to in patients with dementia and it also implicates the diagnostic assessment for depression has clinically importance in patients with MCI.