AMYLOID AND TAU PET FINDINGS IN DIABETES-RELATED DEMENTIA

Abstract

We previously found that there was a dementia subgroup with characteristics predominantly associated with diabetes mellitus (DM)-related metabolic abnormalities rather than AD or vascular pathology in patients with dementia associated with DM, referred to as “diabetes-related dementia”. The identification of diabetes-related dementia may be necessary for considering an appropriate therapy and prevention. We studied amyoid (PiB) and Tau (PBB3) PET in subjects with diabetes-related dementia to investigate underlying pathological conditions. Eleven subjects with diabetes-related dementia underwent PiB PET to evaluate amyloid accumulation in the brain, and 5 subjects underwent PBB3 PET to evaluate tau accumulation. A trained neuroradiologist, who was blind to subjects’ clinical data, performed visual assessments of the accumulation on PiB and PBB3 PET images. Four out of 11 subjects with diabetes-related dementia were rated as positive PiB, 5 as negative PiB, and 2 as equivocal PiB. Although subjects with negative PiB showed lower frequency of ApoE4 carrier than those with positive PiB, there were no significant differences in demographic characteristics. Most subjects who underwent PBB3 PET were positive PBB3, indicating tauopathy. However, the distribution of PBB3 accumulation showed various patterns. Our PET studies indicate that some subjects with diabetes-related dementia showed negative PiB, but positive PBB3. These findings suggest that tauopathy underlies in the brain of diabetes-related dementia. However, the distribution pattern were different from other tauopathies, such as frontotemporal dementia, argyrophilic grain disease, and others. We suspect that tauopathy and nonspecific brain damage due to glucose toxicity are associated with diabetes-related dementia.