Elevation in Late-Life Depression of Intercellular Adhesion Molecule-1 Expression in the Dorsolateral Prefrontal Cortex

OBJECTIVE: Late-life depression may be associated with vascular disease. The authors investigated this association by determining whether intercellular adhesion molecule-1 (ICAM-1), a marker of ischemia-induced inflammation, is elevated in the dorsolateral prefrontal cortex in depression. METHOD: The authors studied postmortem tissue from 20 depressed subjects and a matched comparison group of 20 nondepressed subjects. They used immunocytochemistry to stain ICAM-1 in blood vessels on sections of the dorsolateral prefrontal cortex and occipital cortex and quantitative true color image analysis to measure the proportion of vessels expressing ICAM-1. RESULTS: ICAM-1 was significantly higher in both the gray and white matter of the depressed subjects’ dorsolateral prefrontal cortex than the comparison subjects’ dorsolateral prefrontal cortex. The difference between these groups was much smaller in the gray and white matter of the occipital cortex. CONCLUSIONS: These findings support the vascular depression hypothesis, which has important implications for the understanding and management of late-life depression.