Depression and APOEε4 Status in Individuals with Subjective Cognitive Decline: A Meta-Analysis

Objective To evaluate the associative role of depression and apolipoprotein E epsilon 4 allele (APOE epsilon 4) in subjective cognitive decline (SCD) and its progression to objective cognitive decline. Methods After literature search in electronic databases, studies were selected by following precise eligibility criteria. Meta-analyses were performed to examine the role of APOE epsilon 4 and depression in SCD or its progression to mild cognitive impairment (MCI) or dementia. Results APOE epsilon 4 positivity was not different between SCD and normal individuals but was significantly higher in individuals with SCD plus than in normal individuals [odds ratio: 2.39 (95% CI: 1.87, 3.05); p<0.00001] and in SCD converters than in non-converters [odds ratio: 5.19 (95% CI: 2.36, 11.42); p<0.00001]. Depression was significantly higher in individuals with SCD [standardized mean difference: 0.63 (0.45, 0.82); p<0.00001] and SCD plus [standardized mean difference 0.83 (0.43, 1.22); p<0.0001] than in normal individuals. However, depression was not different between SCD and MCI or between SCD converters and non-converters. Age of SCD converters was higher than non-converters [mean difference: 2.95 years (0.58, 5.31)]. Conclusion Whereas APOE epsilon 4 positivity was higher in SCD plus and SCD converters, depression was higher in SCD and SCD plus but was not different between SCD and MCI.