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Patients with type 1 diabetes (T1D) may have advanced brain aging compared with those without T1D, though this didn't come with early signs of Alzheimer's disease-related neurodegeneration, according to a cohort study.

Participants included in the observational EDIC study had consistently higher Spatial Pattern for Recognition (SPARE)-Brain Age scores compared with controls without diabetes, indicating about 6 additional years of brain aging (β = 6.16 and β = 1.04, respectively, P<0.001), reported Mohamad Habes, PhD, of the University of Texas Health Science Center in San Antonio, and colleagues.

"These results support the hypothesis that brain morphology is associated with an accelerating aging process in middle-aged and older-aged adults with a long history of T1D," the researchers wrote in .

However, this difference in brain aging didn't appear to lend itself to any early manifestations of Alzheimer's disease. As measured by the SPARE-Alzheimer disease (AD) scale, both groups had comparable scores. Likewise, there weren't any significant atrophy differences while comparing most temporal lobes between the groups, "which have particularly important influences on SPARE-AD," Habes and team pointed out.

"[This suggests] that, at least within this middle age and older age range, there is no greater atrophy in regions typically affected in [Alzheimer's disease]," they wrote, though they didn't assay for amyloid and tau biomarkers.

Notably, increased brain aging among patients with T1D was associated with lower psychomotor and mental efficiency (β = -0.04, P<0.001), which was not observed in controls free of diabetes.

However, Habes and colleagues said these changes in cognition were "modest" overall, especially given the fact that the average duration of T1D was 38 years.

A few areas of the brain were hit harder in those with T1D, showing significantly more gray matter atrophy, as seen on MRI. These included the bilateral planum temporale, bilateral superior occipital gyrus, right transverse temporal gyrus, and bilateral thalamus, putamen, and pallidum.

"These regions are known to provide important information for the SPARE-BA [brain age] measure," the group explained. "The relatively parallel trendlines of SPARE-BA for T1D participants versus controls, suggest that this acceleration might have happened earlier in life than the age of 45 years old."

Overall, neither SPARE-BA nor SPARE-AD scores were linked with glucose levels or with other diabetes-related complications like neuropathy, retinopathy, or kidney disease.

Interestingly, higher body weight may hold some protective properties against this more rapid brain aging. For example, an increased body mass index and larger waist circumference were both significantly associated with lower brain age-related atrophy and Alzheimer's-related brain atrophy in those with T1D. On the other hand, those with higher diastolic blood pressure had higher brain aging atrophy scores.

For this cohort study, Habes and team included 416 participants from the observational , which began in 1994 and is being conducted across 27 centers in the U.S. and Canada. Median participant age was 60, and 21% were older than 65.

Psychomotor and mental efficiency were measured using verbal fluency, digit symbol substitution test, trail making part B, and the grooved pegboard tests.

Habes and colleagues noted that the main limitation of the study was its predominantly white population, which limits its generalizability to other populations.

Furthermore, "the cohort is at an age where the prevalence of [Alzheimer's disease] pathology is expected to be low," they wrote.

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