Relationship between EEG dimensional complexity and neuropsychological findings in Alzheimer's disease

The aim of the present study was to examine the region-specific correlations between electroencephalography (EEG) dimensional complexity (DC), a measure of non-linear dynamics, and neuropsychological performance in 25 right-handed patients with Alzheimer's disease (AD). Electroencephalography recording sites were according to the international 10-20 system. Neuropsychological tests included Wechelor Adult Intelligence Scale-Revised (WAIS-R) (Full-scale Intelligence Quotient (FIQ), Verbal Intelligence Quotient (VIQ), Performance Intelligent Quotient (PIQ)); Mini-Mental State Examination; Raven's Coloured Progressive Matrices (RCPM); Rey Auditory-Verbal Learning Test (RAVLT); seven word pairs-revised Miyake Paired-Associate Word Learning Test; Benton Visual Retention Test; and Rey Complex Figure Test. A partial correlational analysis was carried out, controlling for age and sex (P< 0.005). The FIQ, VIQ and RCPM scores were found to be significantly correlated with DC at the F3, C3 and T3 electrodes. Significant correlations were also found between RAVLT scores and DC at the C3, P3 and T5 electrodes. The study on AD indicated region-specific correlations between DC and neuropsychological performance: one between the DC value in the left frontal, central and mid-temporal areas and intellectual function; and another between the DC value in the left central, parietal and post-temporal areas and verbal memory. Dimensional complexity would therefore seem to be a useful indicator for the assessment of neuropsychological deficits in AD.