Depressive symptoms and cognitive function in the U.S. POINTER study.

OBJECTIVE

This study aimed to examine the extent to which the well-established association between depressive symptoms and cognitive functioning was present in the U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER) participants at baseline.

METHODS

We examined the association of depressive symptoms and cognitive functioning in 2,103 participants (aged 60-79) at baseline for U.S. POINTER, a multisite, 2-year study testing the impact of lifestyle interventions on cognition in older adults at risk for cognitive decline. We measured cognition with the Neuropsychological Test Battery modified for U.S. POINTER and formed composite scores of episodic memory, executive functioning, processing speed, and global cognition. Depression was measured with the 15-item Geriatric Depression Scale (GDS-15). Simple linear regression models controlling for demographics were used to evaluate the relationship between cognitive function and GDS-15 score, first continuously and then dichotomously.

RESULTS

Higher continuous GDS-15 scores were associated with lower global composite scores and slower processing speed, but not episodic memory or executive functioning. In models examining common clinical cut-offs for GDS-15 in two categories (0-4, 5-15), we only found an association between GDS-15 score and processing speed, in the model adjusted for age, education, gender, race/ethnicity, and site.

DISCUSSION

Depressive symptoms, even at low levels and in subclinical ranges, were associated with slower processing speed in a large and diverse group of community-dwelling adults. While the effect size was small, these data are consistent with other studies suggesting that slowed processing speed is one of the earliest cognitive consequences of depression in older adults.