Decreased Spontaneous Brain Activity and Functional Connectivity in Type 1 Diabetic Patients Without Microvascular Complications.

BACKGROUND/AIMS: Type 1 diabetes mellitus (T1DM) has been proven to be associated with an increased risk of cognitive dysfunction. In this study, we aimed to investigate whether disrupted spontaneous activity and functional connectivity (FC) exist in T1DM patients using resting-state functional magnetic resonance imaging (rs-fMRI) and to detect the relationships of these parameters with cognitive impairment.

METHODS: T1DM patients (n=35) were compared with age-, sex-, and education level-matched healthy controls (n=50) through rs-fMRI. Using rs-fMRI professional software, we calculated the amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), and seed-based FC in the posterior cingulate cortex (PCC) to measure the spontaneous neural activity in the groups. The relationship between rs-fMRI data and cognitive performance was further investigated.

RESULTS: Compared with the healthy controls, T1DM patients showed significantly decreased ALFF values in the PCC and right inferior frontal gyrus (IFG), decreased ReHo values in the right middle frontal gyrus (MFG) and reduced FC between the PCC and the right MFG. Furthermore, a positive correlation was found between decreased ALFF values in the PCC and Rey-Osterrieth Complex Figure Test (CFT)-delay scores in T1DM patients (r=0.394, p=0.026). Moreover, the Trail Making Test-B (TMT-B) scores showed negative correlations with decreased ReHo values in the right MFG (r=-0.468, p=0.007) and reduced FC between the PCC and right MFG (r=-0.425, p=0.015).

CONCLUSION: Our combined analyses revealed decreased spontaneous activity and FC mainly within the default mode network, which was correlated with specific impaired cognitive functioning in T1DM. This study thus elucidates the neurophysiological mechanisms underlying T1DM-related cognitive impairment and may serve as a reference for future clinical diagnosis.