Theory of mind in amnestic mild cognitive impairment: an FMRI study

Theory of Mind (ToM) undergoes changes at the behavioral level in pathological aging (Alzheimer's disease (AD)) and at the neural level in physiological aging. The aim was to determine if there are changes in ToM in the behavioral and neural domains in old subjects with high risk of switching from successful to unsuccessful neurocognitive aging. Patients with amnestic mild cognitive impairment (aMCI) syndrome were studied, since aMCI was proposed to fill the gap between normal aging and dementia. Sixteen aMCI patients (mean age 71 years) and fifteen healthy controls (mean age 67 years) with no differences in age or education were subjected to increasingly complex ToM tasks and to fMRI scanning while performing the Reading the Mind in the Eyes test (RME), which attributes mental states by focusing on eye-gaze. aMCI subjects had worse performances in two second order false belief tasks, confirming the decay of ToM on the behavioral level. Despite a minor activation of some components (posterior end of the superior temporal sulcus and temporal pole) of the ToM neural circuit, no significant differences in the behavioral performances to the RME was found in aMCI compared to controls. Probably the preservation of the mirror neuron system (precentral gyrus-BA 6; Broca area - BA 44) and the stronger involvement of frontal areas (middle and medial frontal cortex and anterior cingulate cortex) supplemented the decay of part of the mentalizing neural circuit, preserving task performance.