ASSOCIATION BETWEEN WHITE MATTER HYPERINTENSITIES, FRONTAL BRAIN VOLUMES AND NEUROTICISM IN LATE LIFE DEPRESSION

Abstract

Introduction The neurobiology of neuroticism in late life depression (LLD) is understudied. Previous structural imaging research has linked both smaller hippocampal volumes and greater volume of vascular white matter changes to LLD. We hypothesized older depressed subjects scoring high in measures of neuroticism would have smaller hippocampal volumes compared with non-neurotic older depressed subjects and with non-depressed controls. Methods Non-demented subjects were recruited and were either depressed with high neuroticism, depressed with low neuroticism or not depressed (control). Neuroticism was assessed using the NEO PI. A study psychiatrist confirmed or ruled out diagnosis of depression for depressed and control subjects. Brain MRIs were performed. Results The study sample consisted of 128 older depressed subjects and 36 never depressed controls. Subjects had a mean age of 72 and were 70% female. 50% of depressed subjects scored high on the NEO-PI neuroticism measure. For outcomes focusing on white matter changes, we found that non-neurotic depressed subjects had a higher volume of white matter vascular change than did neurotic depressed subjects and non-depressed controls. For imaging outcomes focused on volumetric analyses, we several frontal lobe regions for which depressed subjects with high neuroticism scores had smaller volumes compared with non-neurotic older depressed subjects and with non-depressed controls, controlling for age and gender. These regions included frontal pole, medial orbitofrontal cortex and left pars orbitalis. We did not find significant between-group differences in hippocampal volume. Conclusions In late-life depression hippocampal volume was not associated with depression or neuroticism. Our finding that those depressed subjects low in neuroticism had higher white matter vascular change volumes is consistent with prior literature on “vascular depression.” However, our finding that those high in neuroticism had similar white matter vascular change to controls implies that there may be a different neurobiological mechanism in older neurotic depressed group. This notion is supported by our finding that several frontal lobe structures were smaller in patients who scored high in measures of neuroticism than in non-neurodepressed subjects and in non-depressed controls. Our results suggest that multiple biological pathologies that can lead to different clinical expressions of LLD. This research was funded by The Leo and Anne Albert Charitable Trust National Institute of Mental Health Grant R01 MH108578