Circumscribed cognitive dysfunction in middle-aged adults with type 2 diabetes.

Abstract

OBJECTIVE -To examine the extent to which type 2 diabetes is associated with poorer performance on measures of learning, memory, psychomotor speed, and problem-solving in middle-aged adults. RESEARCH DESIGN AND METHODS-This cross-sectional study evaluated 50 adults (age range 34-65 years, mean 50.8) with type 2 diabetes and 50 demographically similar community control subjects without diabetes. Each subject received a thorough physical examination and a detailed neuropsychological assessment. Factor analysis was used to assign specific tests to 1 of 4 cognitive domains (learning, memory for stories, problem-solving, and psychomotor speed). Hierarchical regression analysis was used to identify demographic and biomedical variables associated with cognitive dysfunction.RESULTS -Learning, memory, and problem-solving skills were unaffected by type 2 diabetes. In contrast, psychomotor slowing was predicted by a diagnosis of diabetes (r 2 change = 0.075, P Ͻ 0.002) with additional variance in psychomotor efficiency explained independently by HbA 1 (r 2 = 0.064, P Ͻ 0.003) and vibratory threshold (r 2 = 0.112, P Ͻ 0.0001). The magnitude of psychomotor slowing on specific tests ranged from 12% (Digit Vigilance) to 23% (Grooved Pegboard).CONCLUSIONS -Middle-aged adults with type 2 diabetes manifest psychomotor slowing that is associated with poorer metabolic control, whereas learning, memory, and problemsolving skills appear to be largely intact. The development of psychomotor slowing may be a manifestation of a "central neuropathy" induced by chronic hyperglycemia.

Cognitive efficiency declines over time in adults with Type 1 diabetes: effects of micro- and macrovascular complications

“…We and others have previously shown that mental and motor slowing is a nearly ubiquitous sequela of both Type 1 and Type 2 diabetes [2,3,5,30,31]. This prospective assessment confirms those earlier cross-sectional findings by showing that over time, 39% of our diabetic sample showed a marked (more than 0.5 SD units) decline on a composite measure of psychomotor efficiency, whereas only 9% of our non-diabetic comparison group showed a similar decline.…”

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

“…There is accumulating evidence that diabetes, in addition to increasing the risk of cardiovascular disease, stroke and kidney failure, may also adversely affect brain function independently from atherosclerotic disease. To date, numerous studies have demonstrated that type 2 diabetes is associated with cognitive deficits (for example [2][3][4][5]). …”

Diabetes and behavioral medicine: The second decade.

“…More recent research has documented MRI abnormalities in adults with T1DM (Araki et al, 1994;Jacobson et al, 2000), although the clinical significance of these is unknown. Because one of the best predictors of cognitive-motor impairments in adults appears to be the presence of peripheral neuropathy, Ryan and colleagues (Ryan & Geckle, 2000;Ryan, Williams, Orchard, & Finegold, 1992) have suggested that another long-term complication of chronic hyperglycemia may be a "central neuropathy," or damage to neural structures in the central nervous system. However, some neuropsychological decrements associated with hyperglycemia may be reversible because improving diabetes control appears to enhance learning and memory performance (Gradman, Laws, Thompson, & Reaven, 1993).…”