Associations between depressive symptoms and memory deficits vary as a function of insulin-like growth factor (IGF-1) levels in healthy older adults.

OBJECTIVES: Accumulating evidence suggests an adverse association between depressive symptoms and cognition, but a positive association between insulin-like growth factor (IGF)-1 and cognition. The present study examined the influence of IGF-1 in the relationship between depressive symptoms and learning and memory. METHODS: A cross-sectional study of 94 healthy fit older adults. Blood was collected and plasma IGF-1 was measured. Depressive symptoms were assessed with the Geriatric Depression Scale (GDS), and learning and memory were assessed using the Rey Auditory Verbal Learning Test (AVLT). RESULTS: Among older adults with lower IGF-1 levels, higher depressive symptoms scores were associated with lower AVLT delayed recall and recognition. Older adults with higher IF-1 levels showed no associations between depressive symptoms and memory. CONCLUSIONS: The association between depressive symptoms and cognition is stronger among older adults with lower levels of circulating IGF-1. Further validation studies on groups with depression or different stages of cognitive impairment are needed. IGF-1 may be a novel intervention target for slowing cognitive decline in older adults with depressive symptoms.