P1‐215: CORTICAL SOURCES OF RESTING STATE EYES CLOSED EEG RHYTHMS ARE CORRELATED TO CEREBROSPINAL FLUID Β AMYLOID IN AMNESTIC MCI SUBJECTS

Mild cognitive impairment (MCI) subjects were previously characterized by abnormal cortical sources of resting state electroencephalographic (EEG) rhythms but it is unclear the specificity of this result with reference to Alzheimer's disease (AD). To address this issue, IMI PharmaCoG project (Grant Agreement n°115009, www.pharmacog.org) evaluated whether cortical sources of these rhythms are correlated to cerebrospinal fluid (CSF) β amyloid (Aβ) level in amnesic MCI subjects. The research data (including human biological samples) were sourced ethically and their research use was in accord with the terms of the international ethical standards. Artifact free resting state eyes-closed EEG rhythms (19 electrodes) were recorded in the context of WP5 planning the enrolment of 147 individuals (analysis of additional individual EEG datasets is in progress, so the present results are just preliminary). Individual data sets were broken down into those with high CSF Aβ level (57 MCI NEG, CSF Aβ > 550 pg/ml) and those with low CSF Aβ level (38 MCI POS, CSF Aβ < 550 pg/ml). Cortical sources of EEG rhythms at frequency bands of interest (delta <4 Hz, low-frequency alpha 8-10.5 Hz) were estimated by LORETA package. ANOVA compared these sources between the two MCI groups (p<0.05, corrected). Furthermore, these sources were correlated to CSF Aβ level across all MCI subjects as a whole group (Pearson test, p<0.05). We observed no statistically significant difference of these cortical sources between the two groups (p>0.05). In contrast, there was a statistically significant negative correlation between global delta sources and CSF Aβ level (r= -0.28; p=0.007) across all MCI subjects (Figure 1).