BRAIN ABNORMALITIES DEMONSTRATED BY MAGNETIC-RESONANCE-IMAGING IN ADULT IDDM PATIENTS WITH AND WITHOUT A HISTORY OF RECURRENT SEVERE HYPOGLYCEMIA

OBJECTIVE - Previous studies of a cohort of 100 patients with IDDM hav e shown that a history of recurrent severe hypoglycemia is associated with a modest impairment of cognitive function. The aim of the present study was to determine whether IDDM patients with and without a histo ry of severe hypoglycemia have lesions in the brain that are identifia ble by magnetic resonance imaging (MRI) and magnetic resonance spectro scopy (MRS) and to investigate the putative relationship of any struct ural brain abnormalities with cognitive function. RESEARCH DESIGN AND METHODS - MRI and MRS of the brain were performed in 22 patients from the original cohort. Eleven IDDM, patients with no history of severe h ypoglycemia (group A) were compared with 11 IDDM patients who had a hi story of five or more episodes of severe hypoglycemia (group B). RESUL TS - Nine patients (41%) had abnormal scans. Two types of abnormalitie s were observed: high-intensity rounded lesions, >3 mm in diameter, di stributed in the periventricular white matter (leukoaraiosis) in four patients; and cortical atrophy in five patients. Five patients in grou p B had cortical atrophy, whereas no patient in group A demonstrated t his feature (P < 0.05). MRS of the frontal and parietal lobes showed n o differences in the N-acetyl aspartate/creatine or N-acetyl aspartate /choline ratios between groups A and B. Patients with cortical atrophy showed a nonsignificant trend toward reduced performance on Rapid Vis ual Information Processing. CONCLUSIONS - Brain abnormalities demonstr ated by MRI are common in patients with IDDM of long duration and are suggestive of premature aging of the brain. IDDM per se may be an impo rtant pathogenic factor, but a significant association was observed be tween a history of recurrent severe hypoglycemia and cortical atrophy, which may be related to the modest impairment of cognitive function t hat has been reported previously.