Depressive symptoms in older adults are associated with decreased cerebral oxygenation of the prefrontal cortex during a trail-making test.

Abstract

Growing evidence supports the relationships between depressive symptoms, cognitive decline, and brain structural changes in older adults. The purpose of this study was to determine whether depressive symptoms are related to cerebral oxygenation during cognitive tasks in older adults. In this study, 80 elderly subjects (73.9 ± 5.4 years, 34 males) were evaluated using multi-channel Near-infrared spectroscopy. Concentration changes (mmolcm/l) in oxy-hemoglobin (oxy-Hb), as the most reliable available indicator of changes in regional cerebral blood flow, in the right and left prefrontal cortex were measured during the Trail Making Test Part B (TMT-B). Depressive symptoms were assessed using the short Geriatric Depression Scale (GDS). Subjects were divided into a depressive group (GDS greater than or equal to 6) and non-depressive group (GDS lower than 6). In results, Oxy-Hb activation during the TMT-B was significantly smaller in the depressive group (n=13) than in the non-depressive group (n=67) in both the right and left prefrontal cortex. In the multivariate analysis, GDS scores were significantly negatively correlated with oxy-Hb activation after adjusting for age, gender and educational history (right, β=-0.32, p=0.002; left, β=-0.25, p=0.02). Less prefrontal activation in older adults with depressive symptoms may account for decline in executive function. Further studies are needed to investigate the influence of the less brain activation associated with depressive symptoms on future cognitive decline and structural brain changes in older adults.