Aim/hypothesis: Underlying mechanisms for decreased cognitive functioning in patients with type 2 diabetes are unclear. In the general population, cerebral hypoperfusion is a risk factor for cognitive dysfunction and dementia. Reduced cerebral perfusion may account for cognitive impairments in diabetic patients relative to controls.
Methods: A total of 98 patients with type 2 diabetes and 47 control participants underwent neuropsychological evaluation. Total cerebral blood flow (CBF) was assessed non-invasively by measuring the volume flow in the internal carotid arteries and basilar artery with two-dimensional phase-contrast magnetic resonance angiography. Relative total CBF, a measure of mean total cerebral perfusion, was obtained by expressing total CBF per 100 ml brain parenchyma volume.
Results: Patients with type 2 diabetes performed worse on neuropsychological tests (p < 0.05). Total CBF per 100 ml brain parenchyma volume did not differ between participants with and without diabetes (difference -2.3 ml min(-1) 100 ml(-1); 95% CI -6.0, 1.3). In the entire group, total CBF per 100 ml brain parenchyma volume was positively associated with cognitive functioning (0.09 SD increase in composite z score per 10 ml min(-1) 100 ml(-1) increase in relative total CBF). This association was not affected by type 2 diabetes.
Conclusions/interpretation: Although total CBF per 100 ml brain parenchyma volume was associated with cognitive functioning, it did not explain cognitive impairments in patients with type 2 diabetes relative to controls.