Cognitive reserve as a protective factor moderating the effect of depressive mood on memory impairment

Abstract

The cognitive reserve hypothesis holds that older adults show individual differences in their flexibility and efficiency in using available neural resources. Those with higher cognitive reserve show better cognitive functioning, including memory, and can tolerate higher levels of brain pathology before displaying clinical symptoms (Stern, 2002

Scarmeas & Stern, 2004). Studies have shown that depressed patients perform comparatively poorly on memory tasks, and many have associated depression with a significantly increased risk of dementia (Cohen et al., 1982

Burt et al., 1995). This study was conducted to test whether cognitive reserve, measured by years of education and premorbid IQ, can moderate the negative effect of depressive mood on memory performance. 79 healthy, non-demented elderly aged 61 to 87 were recruited from eight different senior centers in Seoul, South Korea. The GDS was used to measure depressive mood, the Elderly Verbal Learning Test (EVLT) was used to measure short-term recall, long-term recall, and recognition memory, and the K-WAIS-IV Vocabulary subtest was used as an index of premorbid IQ. The results showed that receiving more years of education, but not having a higher premorbid IQ, significantly reduced the negative association between depressed mood and memory function. Subjects with low education had declining memory test scores depending on level of depression. However, subjects with high education displayed relatively stable memory function despite level of depression, implying that education has more protective effects against memory impairment than premorbid intelligence does.