ERP and Microstates of memory: Frequent alcohol-induced blackouts do not change behavioural performance but alter sober neural functioning

Abstract

It is widely accepted that excessive alcohol consumption has detrimental long-term effects on health and cognitive functioning. One notable but rarely studied phenomena is the experience of an alcohol-induced memory blackout (MBO), a short-term amnesic episode resulting from extreme binge-drinking. It is currently unknown whether the frequency of MBOs experienced in the past imparts any lasting changes in either cognition or at the neural level. Given that MBOs cause immediate impairments in memory, we reasoned that memory may also be affected in the long-term. To test this hypothesis, we examined neural activity associated with memory retrieval in (sober) participants who reported frequent alcohol-induced MBOs (9 or more in the past 12 months; n=20), and control participants (n=21) who have never experienced an MBO. Memory was assessed using word recognition (discriminating old from new stimuli) with a secondary source judgement (remembering colour information), a task that both MBO and control participants could easily perform. Neural activity was measured by recording electroencephalography (EEG) during the memory test, allowing the processes associated with memory retrieval to be characterised. The EEG data was examined using Event-Related Potentials (ERPs) and microstate segmentation, revealing clear differences in retrieval processing between MBO participants and controls. Critically, the neural data revealed that control and blackout participants employed different retrieval strategies to achieve similar levels of memory performance. The present findings provide evidence that repeated alcohol-induced MBOs are associated with altered cognitive functioning, highlighting the need for longitudinal studies examining the compound effects of MBOs and their impact on health, behaviour and quality of life.