Impact of Psychiatric Comorbidity on Cognitive Performance and EEG Theta/Beta Ratio: A Preliminary Study

Background/Objectives: Psychiatric conditions are highly prevalent and among the leading causes of disability worldwide. Comorbidities are common in psychiatric patients but are not adequately addressed in diagnostic manuals such as the DSM-5. Understanding the impact of comorbidities on patients’ symptoms and brain activity could improve the personalization of therapeutic approaches, leading to better outcomes. Given the complexity of this task, a feasible strategy is to examine how comorbidities affect brain activity and a condition commonly observed in psychiatric patients, such as cognitive impairment. Methods: In this study, we assessed impulsiveness, working memory performance, and theta/beta ratio in controls and in subjects exhibiting symptoms of depression, ADHD, and suicide risk. Participants differed in the presence of alcohol use disorders, in addition to the aforementioned symptoms, either presenting no alcohol use disorder (DAS), hazardous alcohol consumption (DAS-H), or risk of alcohol dependence (DAS-D). Results: All three comorbid groups (DAS, DAS-H, DAS-D) showed increased impulsiveness compared with controls, while the DAS-D group also exhibited higher motor impulsiveness than both the DAS and DAS-H groups. A widespread increase in theta/beta ratio was observed only in the DAS group. Conclusions: These results indicate that comorbid alcohol use disorders modulate motor impulsiveness and theta/beta ratio in subjects with symptoms of depression, ADHD, and suicide risk. The findings underscore the importance of considering comorbidities when personalizing treatment strategies for psychiatric patients.