Neuroanatomical Characteristics of Geriatric Apathy and Depression: A Magnetic Resonance Imaging Study

Abstract

Apathy is one of the most common late-life neuropsychiatric syndromes. The objective of our study was to examine the neuroanatomical correlates of apathy in older subjects with and without geriatric major depression (MDD). Eighty-four subjects (43 patients with MDD and 41 normal comparison subjects) underwent comprehensive neuropsychiatric examination, physical examination, and high-resolution magnetic resonance imaging (MRI) brain scans on a 1.5T GE MRI scanner. Apathy was assessed using the Apathy Evaluation Scale. MRI image analyses included cortical surface extraction, tissue segmentation, and cortical parcellation methods to measure the gray and white matter volumes in two prefrontal subregions: the anterior cingulate and orbitofrontal cortex. The depressed group had smaller orbitofrontal gray matter volumes compared to the age-matched normal comparison group. The severity of apathy was associated with the decreased gray matter volume in the right anterior cingulate gray matter volumes using partial correlation and regression analyses after controlling for age, sex, and diagnosis. Apathy and depression were associated with different anatomical correlates in the prefrontal regions implicated in the regulation of cognition and emotion. Our findings offer new understanding of the neuroanatomical characteristics of apathy and depression in late life, and have broad implications for the neurobiology of behavior.