Electrophysiological signatures of memory depletion in mild cognitive impairment

Abstract Background MCI diagnosis does not necessarily imply the development of dementia. For this reason, characterizing the MCI profile is fundamental to the early identification of electrophysiological markers associated with a higher risk of developing Alzheimer’s Disease (AD). Longitudinal studies demonstrated that the delay recall measure is a good predictor of conversion and is one of the most common manifestations of the preclinical stage. This study has for purpose compared the power spectrum in the resting‐state of MCI and their relationship with neuropsychological and structural measures. Method We compared the power spectrum in resting‐state eyes‐closed magnetoencephalographic of 93 MCI participants (aged from 64 to 87) recruited from the Hospital Universitario San Carlos (Madrid, Spain). According to their memory performance in delay recall, the sample was split into (i) ‘moderate’ MCI (n = 52) group and (ii) ‘severe’ MCI (n = 41) group. The groups did not differ in age or years of education. Results The severe MCI patients showed higher theta power than patients with moderate MCI were significant differences between both. Also, moderate MCI correlated significantly with years of education (rho = ‐0.31, p < 0.02) and TMT A time (rho = 0.40, p < 0.004). In the Severe MCI group, the theta power showed significant correlation with MMSE (rho = ‐0.43, p < 0.001) and total hippocampus (rho = 0.41, p < 0.001). Conclusion Loss of delay recall performance seems to be associated with electrophysiological alterations that can be used as non‐invasive markers of AD progression.