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

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.

[White matter hyperintensities and cognitive function in patients with late onset mania]. / Lesiones hiperintensas de la sustancia blanca y función cognoscitiva en pacientes con manía de inicio tardío.

Bipolar disorder is characterized by affective episodes in the mania-depression spectrum. Ninety per cent of the cases have an onset before age 50. In the patients with late onset mania, white matter hyperintensities (WMH) may be seen in the MRI FLAIR sequence, although these are of uncertain significance. A case-control study was done, including patients with late onset mania attended at the National Institute of Neurology and Neurosurgery, as well as healthy controls which were paired by age, sex, and academic level. Sagital FLAIR CUBE volumetric images were obtained, and later on assessed by an expert neuroradiologist, blinded to the diagnostic category. Neuropsychological measures were obtained. The patients with late onset mania showed statistically significant deficiencies (p < 0.05) in motor programming tasks, and inhibitory control tasks, according to the Frontal Assessment Battery, as well as a significant increase in the number of WMH in the right third frontal gyrus, the left first temporal gyrus, and the left second temporal gyrus. The total number of WMH and the Frontal Assessment Battery total score showed a significant inverse correlation.