Subbands analysis of amplitude of low-frequency fluctuations in type 2 diabetes mellitus patients: a resting-state functional MRI study

Abstract

Objective To investigate changes of spontaneous brain activity in patients with type 2 diabetes mellitus (T2DM) by fractional amplitude of low-frequency fluctuations (fALFF) on subbands, and the possible relationship between these changes and cognitive impairment caused by T2DM. Methods Twenty-two T2DM patients and twenty-three healthy control subjects were involved in this study between December 2013 and June 2014 and the demographic and clinical data (fasting plasma glucose and HbA1c level) were obtained in all subjects. General cognition was assessed by MMSE in all subjects, and memory performance was assessed by Auditory Verbal Learning Test (AVLT) in T2DM group. 3D-T1 structural and resting-state functional MRI data were collected by MR scanner. Then fALFF value on slow-5 (0.010-0.027 Hz) and slow-4 (0.027-0.073 Hz) were calculated respectively using DPARSF V2.3. Intra-group and inter-group t-tests were conducted by REST V1.8. Partial correlation among fALFF values extracted from significantly different brain regions, clinical data and AVLT score of T2DM patients were calculated , using age as covariate. Results Compared to the healthy controls, T2DM patients showed increased fALFF values in bilateral anterior cingulate gyrus (cluster=130, t=4.4487, P<0.05) and partial left cerebelum areas (cluster= 89, t=3.8409,P<0.05) in frequency band slow-5. Moreover, the T2DM patients showed decreased fALFF values in bilateral middle occipital gyrus and precuneus (Left: cluster=102,t=-3.4806. Right: cluster=151,t=- 5.1355. All P<0.05) in frequency band slow-5. While in frequency band slow-4, the T2DM patients showed increased fALFF values in left inferior temporal gyrus (cluster=104, t=4.8631, P<0.05), and decreased fALFF values in right lingual gyrus (cluster=91, t=- 3.7146, P<0.05). There was positive correlation between fALFF values of middle occipital gyrus and precuneus and AVLT immediate memory score (r=0.456 , P=0.038). Conclusions T2DM patients exhibit abnormal spontaneous activity among brain regions associated with cognition, including brain regions related to default mode network on slow-5, and brain regions related to semantic cognition and visual information processing on slow-4. The abnormal regions exhibit different spatial patterns depending on the subbands of low-frequency fluctuations. Key words: Diabetes mellitus, type 2; Magnetic resonance imaging; Cognitive science