Delta and Theta Activity Provide Shared and Unique Sensitivity to Alcohol and Cocaine Use Disorder

The P300 amplitude reduction, or P3AR, is a decrease in the magnitude of the P300 event-related potential (ERP) waveform, typically measured via EEG during oddball tasks, and widely observed in those diagnosed with Alcohol use Disorder (AUD). Though widely acknowledged as a biological correlate of AUD, most of the extant literature on the P3AR features conventional time-domain measurement approaches, and further, the work has predominantly focused on alcohol use specifically. In order to precisely capture the nature of this association as well as assess generalizability to other substances, the current study utilized advanced time-frequency analyses to compare P3 activity in individuals with AUD, cocaine use disorder, and comorbid alcohol and cocaine use. Time-frequency analyses indexed separable theta and delta activity underlying the conventional time-domain P3. Findings revealed that in the conventional time-domain, we observed P3AR shared across alcohol and cocaine use. These findings replicate literature suggesting P3AR associated with substance use. Within time-frequency analyses, we found broad delta reductions across substances, aligning with literature suggesting that delta is mostly comprised of the P3 ERP. For theta-band activity, we found reductions in. amplitude specific to alcohol users only, with no significant diminutions present for cocaine users. As most previous literature focused on alcohol use, unique theta modulations relative to cocaine users provides theoretical clarity in terms of the association of P3AR to substance use more broadly. The findings of the current study highlight the utility of time-frequency measurement approaches in parsing overlapping activity and indexing separable processes with relevance to substance use otherwise unaccounted for in the time domain.