Abstract

Background: Depression has been known to affect memory and other cognitive domains. The objective of this longitudinal cohort study was to investigate longitudinal associations between depressive symptoms at age 31 years and visual memory and new learning at the age of 46 years. We investigated whether depressive symptoms at age 31 predicted visual memory deficits at age 46 years, and whether changes in depressive symptoms between 31 and 46 years predicted visual memory at age 46.

Methods: Participants were members of the Northern Finland Birth Cohort 1966. Depressive symptoms were assessed with the Symptom Checklist-25 (SCL-25) on both occasions. Visual memory and new learning were assessed using Paired Associative Learning (PAL) test at the age 46 follow-up. PAL total errors adjusted and first trial memory score were used as outcomes and basic educational level, relationship status, physical activity and diet at baseline were considered as confounding factors in linear regression analysis.

Results: A total of 5029 (57% female) participants were included in the main analysis. No associations were found between depressive symptoms or change in depressive symptoms and visual memory and new learning scores. The result did not change following cut-offs 1.55 and 1.75 for depression.

Limitations: SCL-25 only measures symptoms during the past week. Only one cognitive domain was assessed.

Conclusions: Contrary to our hypothesis, neither baseline depressive symptoms nor change in depressive symptoms predicted visual memory scores 15 years later. It appears that sub-clinical depressive symptoms do not effect this cognitive domain in the middle-aged population.