Relationship between cognition, magnetic resonance white matter hyperintensities, and cardiovascular autonomic changes in late-life depression.

Objectives: To explore the relationship between specific aspects of cognition, white matter hyperintensities (WMHs), and cardiovascular autonomic parameters in late-life depression (LLD).
Design: Cross-sectional analysis.
Setting: Secondary care psychiatry.
Participants: Forty-one individuals older than 60 years, with current or previous history of major depression, and 32 age-matched comparison subjects.
Measurements: Cognition was assessed by a standardized computer battery of tasks (Cognitive Drug Research) that measured processing speed, attention, episodic memory, and working memory. Cardiovascular autonomic parameters were estimated by a noninvasive device that calculated blood pressure, heart rate variability, and baroreflex sensitivity (Task Force Monitor). Magnetic resonance imaging was performed on a 3-T magnetic resonance imaging system, and WMH volume was estimated using an automated validated method.
Results: As expected, cognitive deficits in all tested domains were present in LLD subjects compared with comparison subjects. In the LLD group, processing speed was correlated with scores on memory and working memory tasks. Attentional deficits were correlated with total and periventricular WMH volume, and episodic memory was associated with heart rate variability. There were no associations between cognitive variables and traditional vascular risk factors or between cognitive variables and any of these parameters in the comparison subjects.
Conclusions: This study suggests that processing speed may be an important factor underlying deficits in LLD, but it also indicates that other factors, including those related to vascular disease, are important and thus provide further support for the vascular depression hypothesis.