The Relationship between Brain Volume Loss and Cognition in Subjects with T2DM

Aim: Mild Cognitive Impairment (MCI) is thought to be a chronic sequelae of type 2 diabetes (T2DM). Cerebral atrophy is known to be associated with cognitive decline, particularly in dementia. Cerebral tissue volumes, in areas associated with cognitive function, were examined in matched patients with T2DM subjects and early cognitive decline. The aim of this study was to compare T2DM patients with and without MCI to identify regional brain volume changes that were specific to MCI.

Method: Seventy-six age and gender matched subjects [30, T2DM+normal cognition (T2DM); 17, T2DM+MCI (T2DM/MCI) and 29, healthy volunteers (HV)] were recruited. All subjects underwent clinical and questionnaire (Addenbrooke’s Cognitive Assessment [ACE-R]) assessments and high-resolution, 3D T1-weighted Magnetic Resonance Imaging (MRI, 3T Philips Ingenia). Cerebral volumes were analysed using voxel based morphometry (VBM, FSL, Oxford).

Results: Demographic data revealed aged-matched participants between all three groups (mean age 69.3-71.5 years, ANOVA, p = 0.164). Mean age of last education was significantly lower in the T2DM/MCI group (mean±SD;15.1 ±0.9 when compared to the other groups (HV 19.3±5.6, T2DM 17.1±2.9) Kruskal-Wallis, p = 0.003. T2DM/MCI ACE-R score (mean±SD; 83±4) was significantly lower compared to other groups (HV=96±2, T2DM=94±3; ANOVA, p<0.001). T2DM/MCI group had significantly lower regional cross-sectional grey matter volumes compared to HV in the left (p#x003C;0.0005) and right hippocampi (p<0.05), left putamen (p<0.05), caudate (p<0.05) and amygdala (p<0.05).

Conclusion: This study demonstrates significantly lower cortical differences in areas associated with cognition in patients with T2DM and early cognitive impairment. Further investigation of both anatomical and functional cerebral involvement is required to examine the pathological mechanisms underlying the increased cognitive impairment risk associated with T2DM.