Abnormal EEG Power Spectrum in Individuals with High Autistic Personality Traits: an eLORETA Study

Autistic traits lie on a continuously distributed spectrum ranging from non-clinical to clinical conditions. Indeed, autistic traits have been observed in general population at sub-threshold levels. Here, the main aim was to investigate differences in resting state (RS) electroencephalographic (EEG) power spectrum in individuals with high vs. low autistic traits. Fifty undergraduates completed the Autism-Spectrum Quotient (AQ) and the Empathy Quotient (EQ). For each participant five minutes of RS-EEG were recorded and analysed by means of the exact Low-Resolution Electromagnetic Tomography software (eLORETA). A Two-Step Cluster Analysis revealed two groups: high autistic traits (AT+) and low autistic traits (AT-) group. Compared to AT-, AT+ individuals showed an increase of delta power in parietal/occipital and cortico-limbic areas. No alterations were observed in other frequency bands. Furthermore, both AQ and EQ total scores were positively correlated with delta EEG power after controlling for sex, age, and subclinical psychopathological traits. Results show that AT+ individuals exhibit an increase in slow RS EEG power in regions involved in self-referential processes, suggesting a reduction in these internally directed mental activities and adding new evidence on the existence of a continuum in the autistic spectrum which spreads from clinical to non-clinical significance.