Introduction: Mild cognitive impairment (MCI) is defined as a state of the ageing brain midway between normal cognition and dementia. Special attention has been paid to the electrophysiological substrate underlying Alzheimer's disease and MCI in order to identify as early as possible which subjects with MCI progress towards Alzheimer, which could be crucial for starting rehabilitation or pharmacological therapies.
Aim: To perform a spectral characterisation of the electroencephalogram in subjects with MCI.
Patients and methods: An electroencephalogram was carried out on 41 subjects with MCI in order to analyse the spectral measurements; apolipoprotein E genotype was also performed.
Results: In all, 94.8% of the sample displayed a significant increase in energy, and in 66.6% of them this was observed in the theta and delta bands, or both. Significant differences were found in the spectral measurements between carriers and non-carriers of the apolipoprotein E epsilon4 allele in the theta and alpha bands; there was also a statistically significant association between the years of schooling and being a carrier of this allele or not. An increase in the theta-alpha bands was observed in the left temporal region in subjects with a below-average number of years of schooling and carriers of the epsilon4 allele.
Conclusions: In subjects with MCI and carriers of the epsilon4 allele, the alpha and theta cortical rhythms can be affected by similar pathological mechanisms and may be expressed earlier in subjects who have a lower level of schooling.