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In dementia-free adults with diabetes, brain atrophy already present

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February 6, 2018

Middle-aged adults with type 2 diabetes without any outward signs of cognitive impairment have less global gray matter volume than healthy adults, an analysis of MRI data from China shows.

“Our data collected from ‘dementia-free’ middle-aged adults with [type 2 diabetes] demonstrate that global brain volume changes, especially lower [gray matter] volume, are already in progress,” Fang Fang, PhD, of the department of endocrinology and metabolic diseases at Shanghai General Hospital and Shanghai Jiao Tong University, China, and colleagues wrote. “Taken together, this and previous reports indicate that brain atrophy may not be limited to a degeneration aging process. Our data suggest that there is an atrophic pathological process that appears to augment the aging process at an earlier stage, manifesting itself in young [type 2 diabetes] subjects who have no significant signs of cognitive impairment.”

In a cross-sectional, observational study, Fang and colleagues analyzed data from 66 adults without dementia (assessed by Mini-Mental State Examination scores) admitted to Shanghai General Hospital between October 2016 and June 2017, including 36 patients with type 2 diabetes and at least one microvascular complication (n = 30), 20 patients with type 2 diabetes but no microvascular complications, and 26 healthy controls. All patients with type 2 diabetes underwent retinal fundus photography to assess for diabetic retinopathy, provided urine samples to measure microalbuminuria and were examined for diabetic peripheral neuropathy. Researchers used voxel-based morphometric analysis on patient MRI images to detect whether early global brain atrophy developed in patients with type 2 diabetes vs. controls.

Researchers observed a difference in mean global gray matter volume among patients with type 2 diabetes and microvascular complications (mean, 0.618), patients with type 2 diabetes and no complications (mean R2 = 0.631) and healthy controls (mean R2 = 0.64; P = .006). In post-hoc analysis, mean gray matter volume was lower among patients with type 2 diabetes with complications vs. controls (P = .003). There were no between-group differences in white matter volume, according to researchers.

In additional post-hoc analyses, researchers also found that patients with type 2 diabetes and microvascular complications had a lower brain volume vs. those with diabetes and no complications and controls (mean coefficient of determination [R2] = 0.72 vs. 0.736 and 0.743, respectively) and observed a negative correlation between total brain volume and diabetes duration (P = .003), BMI (P = .006) and the grading of hypertension (P = .001).

“Even in those without clinical evidence of microvascular complications (diabetic retinopathy, microalbuminuria and diabetic peripheral neuropathy), the development of regional [gray matter] atrophy is already occurring,” the researchers wrote. “The brain seems to be vulnerable to metabolic disturbances, but further, larger and longitudinal studies are required.” – by Regina Schaffer

Disclosure: The authors report no relevant financial disclosures.