Diabetes and Memory

Studies have linked type 2 diabetes to a greater risk of cognitive impairment and dementia, including mild cognitive impairment (MCI) subtypes, amnestic MCI (aMCI) and nonamnestic MCI (naMCI). However, there have been few population-based studies on those associations, say researchers from the Mayo Clinic and Emory University in Atlanta, Georgia. Their long-term study may offer a new approach to resolving “pressing unanswered questions” about the role of diabetes in dementing illness.

The participants, 1,450 adults aged 70 to 89 years, were evaluated at 15-month intervals, starting in October 2004. Over a median 4 years of follow-up, 348 adults developed incident MCI. The incidence per person-years was higher in people with diabetes, particularly men. The incidence for aMCI was higher in men (74.2 in men vs 21.8 in women) but similar for naMCI. In women, diabetes was strongly associated with single-domain naMCI. Men had a higher risk of multiple-domain aMCI and naMCI. Early age at diagnosis of diabetes (aged ≤ 65 years), longer duration of diabetes (about 8 years), and worse glycemic control were associated with higher risk.

MCI subtypes reflect the extent of regional cortical involvement and the underlying etiology of the MCI. “Single-domain MCI syndromes are likely to represent more circumscribed pathology, whereas multidomain MCI may represent more extensive disease,” the researchers say. Amnestic MCI is more likely to be due to Alzheimer disease (AD)—related pathophysiology, the researchers add, whereas naMCI probably includes non-AD type conditions, especially cerebrovascular disease.

The association of diabetes and MCI has important public health implications, the researchers note. Their findings, they suggest, underscore the need to design focused strategies to prevent diabetes and thus reduce the risk of late-life MCI and dementia.

Source
Roberts RO, Knopman DS, Geda YE, et al. Alzheimers Dement. 2014;10(1):18-26.
doi: 10.1016/j.jalz.2013.01.001.