Abstract

Objective: Hyperglycemia-associated microvascular disease may underlie changes in cerebral functioning and cognitive performance in patients with type 1 diabetes mellitus (T1DM). Functional connectivity, an indicator of functional interactions and information exchange between brain regions, provides a measure of cerebral functioning. This study addresses functional connectivity and cognition in T1DM patients with and without proliferative retinopathy, relative to healthy controls, using magnetoencephalography (MEG).

Research Design and Methods: Fluctuations in magnetic field at scalp for delta, theta, lower and upper alpha, beta and lower and upper gamma frequency bands were measured using MEG. Synchronization Likelihood, a measure of functional connectivity, was computed. Using neuropsychological tests, cognitive functioning was assessed and its associations with functional connectivity were determined.

Results: Compared to controls, T1DM patients performed poorer on general cognitive ability, information processing speed and motor speed, irrespective of their microvascular complication status. Functional connectivity, however, was lowest for T1DM patients with retinopathy, as compared to T1DM patients without microvascular complications and controls, whereas T1DM patients without microvascular complications showed an increase relative to controls. Positive associations were found between functional connectivity and executive functioning, memory, information processing speed, motor speed and attention.

Conclusion: Compared to healthy controls, functional connectivity and cognition differed in T1DM patients irrespective of microvascular complication status, indicating that chronic hyperglycemia, amongst other factors, may negatively affect brain functioning even before microvascular damage becomes manifest. The association found between synchronization likelihood and cognition suggest functional connectivity to play a significant role in cognitive functioning.