EEG markers are associated to gray matter changes in thalamus and basal ganglia in subjects with mild cognitive impairment

BackgroundGray matter (GM) changes of thalamus and basal ganglia have been demonstrated to be involved in Alzheimer's disease (AD). Moreover, the increase of two EEG markers, alpha3/alpha2 and theta/gamma ratio, have been associated with, respectively, AD converter and non-AD converter subjects with mild cognitive impairment (MCI).ObjectiveTo study the association of prognostic EEG markers with specific GM changes of thalamus and basal ganglia in subjects with MCI to identify different MCI populations.Methods74 adult subjects with mild cognitive impairment underwent EEG recording and high resolution 3D magnetic resonance imaging (MRI). The theta/gamma and alpha3/alpha2 ratio was computed for each subject. Three groups were obtained according to increasing tertile values of both alpha3/alpha2 and theta/gamma ratio. Gray matter density differences between groups were investigated using a voxel-based morphometry technique.ResultsSubjects with higher a3/a2 ratios when compared to subjects with lower and middle a3/a2 ratios showed minor atrophy in the ventral stream of basal ganglia (head of caudate nuclei and accumbens nuclei bilaterally) and of the pulvinar nuclei in the thalamus; subjects with higher t/g ratio showed minor atrophy in putamina nuclei bilaterally than subjects with middle ratio.ConclusionThe integrated analysis of EEG and morpho-structural markers could be useful in the comprehension of anatomo-physiological underpinning of the MCI entity.

► Association of EEG alpha3/alpha2 and theta/gamma ratio with changes in thalamus and basal ganglia in subjects with MCI. ► EEG markers-driven analysis. ► Increase of alpha3/alpha2 ratio ssociated with minor atrophy of caudate, accumbens and pulvinar nuclei. ► Increase of theta/gamma ratio associated with minor atrophy of putamina bilaterally.