A systematic review found evidence that diazepam can alter emotion processing, while leaving many other social-cognition questions unresolved.
Forty papers were included, eleven examining benzodiazepines and the remainder antipsychotics. Healthy-volunteer experiments suggested reduced emotion-recognition performance with diazepam. Related imaging studies described altered amygdala responses. The authors used narrative synthesis rather than one pooled effect across all measures.
Small samples, variable tasks, and limited randomization constrained interpretation. Healthy-volunteer findings do not automatically describe patients with psychiatric illness or long-term treatment. Emotion recognition is only one component of social cognition.
For testimony, do not translate a laboratory facial-emotion task into a general conclusion about credibility, consent, judgment, or legal capacity. The study supports a possible domain-specific effect that needs connection to the person, exposure, timing, and behavior at issue. It does not provide a universal benzodiazepine impairment score.
Source reviewed: A systematic review of the effects of psychiatric medications on social cognition (PMC8628466). Forensic applications above are interpretive analysis of the supplied paper.
Related reading: Remimazolam PK Review Identified Covariates Rather Than One Universal Recovery Curve; Lorazepam NMS Review Drew From Case Reports Rather Than Controlled Trials.