Type 2 diabetes and atrophy of medial temporal lobe structures on brain MRI

Abstract

Aim/hypothesis. Type 2 diabetes increases the risk not only of vascular dementia but also of Alzheimer's disease. The question remains whether diabetes increases the risk of Alzheimer's disease by diabetic vasculopathy or whether diabetes influences directly the development of Alzheimer neuropathology. In vivo, hippocampal and amygdalar atrophy on brain MRI are good, early markers of the degree of Alzheimer neuropathology. We investigated the association between diabetes mellitus, insulin resistance and the degree of hippocampal and amygdalar atrophy on magnetic resonance imaging (MRI) accounting for vascular pathology. Methods. Data was obtained in a population-based study of elderly subjects without dementia between 60 to 90 years of age. The presence of diabetes mellitus and, in non-diabetic subjects, insulin resistance was assessed for 506 participants in whom hippocampal and amygdalar volumes on MRI were measured. We assessed the degree of vascular morbidity by rating carotid atherosclerosis, and brain white matter lesions and infarcts on MRI.Results. Subjects with diabetes mellitus had more hippocampal and amygdalar atrophy on MRI compared to subjects without diabetes mellitus. Furthermore, increasing insulin resistance was associated with more amygdalar atrophy on MRI. The associations were not due to vascular morbidity being more pronounced in persons with diabetes mellitus. Conclusions/interpretation. Type 2 diabetes is associated with hippocampal and amygdalar atrophy, regardless of vascular pathology. This could suggest that Type 2 diabetes directly influences the development of Alzheimer neuropathology. [Diabetologia (2003[Diabetologia ( ) 46:1604[Diabetologia ( -1610

Hippocampal damage and memory impairments as possible early brain complications of type 2 diabetes

“…However, it should be noted that these researchers used qualitative ratings. Investigators studying cases from a large epidemiological sample have shown that, relative to nondiabetic control subjects, elderly (average age 77.8 years) individuals with type 2 diabetes exhibit reductions in hippocampal and amygdalar volumes [7]; however, no neuropsychological data were reported in this sample. A moderately elevated risk of hippocampal atrophy (odds ratio 1.7, 95% CI 0.9-2.9) has been demonstrated among very old men with type 2 diabetes [8], but it should be noted that this study included individuals with dementia, Alzheimer's disease, strokes, lacunes and high rates of white matter disease.…”

Cognitive dysfunction associates with white matter hyperintensities and subcortical atrophy on magnetic resonance imaging of the elderly diabetes mellitus Japanese elderly diabetes intervention trial (J‐EDIT)

“…Whether variations in glucose homeostasis influence cognitive function remains controversial [49][50][51], although it has been found that the cognitive function of diabetic and nondiabetic subjects fluctuates in accordance with the serum glucose levels [50,51]. At the same time, increased insulin resistance is associated with atrophy of medial temporal lobe structures in elderly diabetic patients [52]. For these reasons, new surrogate markers that reflect chronic hyperglycemia in the diabetic brain are needed.…”

Association Between Diabetes and Hippocampal Atrophy in Elderly Japanese: The Hisayama Study

“…Naoki Hirabayashi, 1,2 Jun Hata, 1,3,4 Tomoyuki Ohara, 1,5 Naoko Mukai, 1,3,4 Masaharu Nagata, 1,4 Mao Shibata, 1,2 Seiji Gotoh, 1,4 Yoshihiko Furuta, 1,4 Fumio Yamashita, 6 Kazufumi Yoshihara, 2 Takanari Kitazono, 3,4 Nobuyuki Sudo, 2 Yutaka Kiyohara, 1,3 and Toshiharu Ninomiya 3 disease, patients with diabetes may have hippocampal atrophy compared with individuals without diabetes. However, previous cross-sectional studies conducted in Western countries showed conflicting results regarding the association between diabetes and hippocampal atrophy (3)(4)(5)(6)(7), and there are no population-based studies examining this issue in Asian populations.…”