Brain Waves in Impulsivity Spectrum Disorders

Impulsivity has proven to be an important psychological construct reflected in both normal and pathological human behaviors and traits. However, the definition, measurement, and manifestations of the construct are varied and multifarious. Impulsive behaviors are observed in a wide range of psychiatric/behavioral disorders, including alcohol/substance use and abuse disorders (AUDs/SUDs), conduct disorder (CD), attention-deficit hyperactivity disorder (ADHD), antisocial (ASPD), narcissistic and borderline personality (BPD) disorders, pathological gambling, and eating disorders, and are variously termed as ‘impulsive’ or ‘impulse-control’, ‘externalizing’, or ‘disinhibitory’ disorders. Studies utilizing sensitive and non-invasive electrophysiological techniques to analyze brain waves in impulsive conditions and disorders have elucidated brain functioning associated with these conditions. These electrophysiological procedures primarily include electroencephalogram (EEG), event-related potentials (ERPs), and event-related oscillations (EROs). Major electrophysiological findings across the majority of the ‘impulsivity spectrum disorders’ include excessive beta power in the resting EEG, decreased P3 amplitude of the ERP, and decreased ERO delta and theta power. This chapter attempts to summarize, explain and synthesize key findings of studies that have used electrophysiological methods to elucidate and understand impulsivity in its normal and pathological manifestations. * corresponding author (Email: [email protected]) Chella Kamarajan and Bernice Porjesz 22