Table 1.

Comparison of brain structural and functional alteration in diabetes and Alzheimer disease.

		Diabetes	Alzheimer disease
Structural change	Gray matter loss	Frontal, temporal lobes, hippocampus (3, 11, 12), anterior cingulate cortex (11)	Temporal lobe, hippocampus, entorhinal, and parietal lobes (13–15)
	White matter loss	Frontal and temporal regions (11)	Temporal region (16)
Functional change	Aberrant functional connectivity	Between posterior cingulate cortex and medial frontal (20)/temporal (19) gyrus	Between posterior cingulate cortex and hippocampus in medial temporal lobe (17, 18)
	Decreased spontaneous brain activity	Occipital lobe and postcentral gyrus (21)	Posterior cingulate cortex, medial temporal lobe (23)
	Task-induced brain activity	Reduced activation of dorsolateral prefrontal cortex during encoding and deactivation of default mode network during recognition (22)	Reduced activation in hippocampal formation but increased activation in medial parietal and posterior cingulate regions during encoding (24)