Involvement of mirror neuron system in prodromal Alzheimer's disease

BACKGROUND: Mirror neurons have been localized in several locations, including the inferior parietal lobule (IPL). Increase of EEG alpha3/alpha2 frequency power ratio has been detected in mild cognitive impairment (MCI) subjects who will convert in Alzheimer's disease (AD). We investigated the association of alpha3/alpha2 frequency power ratio with cortical thickness in IPL in MCI subjects. METHODS: 74 adult subjects with MCI underwent EEG recording and high resolution MRI. Alpha3/alpha2 frequency power ratio as well as cortical thickness were computed for each subject. Three MCI groups were obtained according to increasing tertile values of alpha3/alpha2 ratio. Difference of cortical thickness among the groups was estimated. RESULTS: Higher alpha3/alpha2 frequency power ratio group had wider cortical thinning than other groups, mapped on the IPL, supramarginal gyrus and precuneus bilaterally. CONCLUSIONS: High EEG alpha3/alpha2 frequency power ratio was associated with atrophy of IPL areas in MCI subjects. GENERAL SIGNIFICANCE: The scientific hypothesis is divided into the following main points: 1) the theoretical background considering two recent theories, an evolutionary perspective theory and the theory of mind (ToM), which both track a possible relationship between prodromal AD and mirror system; 2) the relationship has been focused on the prodromal stage of Alzheimer's disease, that is a peculiar and very debated phase of the disease itself; and 3) not a generical relationship, but a focused anatomo-functional association has been proposed.