Altered baseline brain activity in type 2 diabetes: a resting-state fMRI study

This study aims to investigate whether altered baseline brain activity exists in type 2 diabetes mellitus (T2DM) patients using resting-state functional magnetic resonance imaging (rs-fMRI) and whether abnormal neural activity in the middle temporal gyrus (MTG) is correlated with cognitive function.

T2DM patients (n=28) were compared with nondiabetic age-, sex-, and education-matched control subjects (n=29) using rs-fMRI. We computed the amplitude of low-frequency fluctuations (ALFF) of fMRI signals to measure spontaneous neuronal activity and detect the relationship between rs-fMRI information and clinical data.

Compared with healthy controls, T2DM patients had significantly decreased ALFF values in the bilateral middle temporal gyrus, left fusiform gyrus, left middle occipital gyrus, right inferior occipital gyrus; and increased ALFF values in both the bilateral cerebellum posterior lobe and right cerebellum culmen. Moreover, we found an inverse correlation between the ALFF values in the MTG and both the HbA1c (r=-0.451, p=0.016) and the score of Trail Making Test-B (r=-0.420, p=0.026) in the patient group. On the other hand, C-peptide level and pancreatic β-cell function had a positive correlation (r=0.429, p=0.023; r=0.453, p=0.016, respectively) with the ALFF value in the middle temporal gyrus.

The present study confirms that T2DM patients have altered ALFF in many brain regions, which is associated with poor neurocognitive performances, severity of consistent hyperglycemic state and impaired β-cell function. ALFF disturbance in MTG may play a central role in cognitive decline associated with T2DM and serve as reference for future clinical diagnosis.