White Matter Abnormalities in Late Onset First Episode Mania: A Diffusion Tensor Imaging Study.

ABSTRACT

INTRODUCTION: A first manic episode after 50 years of age is uncommon. Late Onset Mania might be indicative of abnormalities in white matter, probably related to vascular, degenerative, or inflammatory processes. OBJECTIVE: To determine if patients with late onset mania have reduced white matter integrity according to Magnetic Resonance Diffusion Tensor Imaging (DTI) and structural MRI. METHODS: Twenty-two patients with late onset mania (>50 years old) and 22 age-paired healthy subjects were included in the study. Fractional anisotropy (FA) was used as a quantitative measure of white matter integrity. Fazekas scale was assessed also to measure white matter abnormalities in the FLAIR sequence. The Frontal Assessment Battery, COGNISTAT and Trail making test A and B were used as cognitive measurements. RESULTS: According to DTI, commissural connections (left corpus callosum), and limbic connections (right and left uncinate fasciculus) were different between the patients and the comparison group. Fractional anisotropy values in the left corpus callosum showed significant correlations with neuropsychological measures, and with the Fazekas scale score. According to Fazekas scale, a pathological score in the FLAIR sequence was significantly more frequent in the patients as compared to the comparison group. CONCLUSIONS: Patients with first episode mania in late life have relevant white matter abnormalities not explained by age, affecting interhemispheric and fronto-limbic networks probably related to executive functioning and emotional processing, at the level of the corpus callosum and the uncinate fasciculus. The etiology of this white matter loss of integrity in patients with late-onset mania is yet to be explored.