In a small preliminary study of 18 patients with treatment-resistant depression given esketamine nasal spray for one month, those who responded to treatment (44.5% of the sample, defined by at least a 30% reduction in depression scores) had lower heart rate variability at baseline compared to non-responders. After one month of treatment, responders' heart rate variability increased. Baseline heart rate variability showed potential to discriminate between responders and non-responders. The findings suggest a link between esketamine treatment and changes in autonomic function measured by heart rate variability, but larger studies are needed to confirm heart rate variability as a predictor of treatment response.
The psychoactive substance 3-MeO-PCP, a type of NMDA receptor antagonist, can cause persistent psychotic symptoms and cognitive impairment. A literature review and case report describe a 29-year-old man who developed substance-induced psychotic disorder after small oral intakes over two weeks, culminating in a high dose. Psychometric tests, neuropsychological assessment, and brain PET-CT imaging revealed lasting effects. Identifying the clinical features and neural substrates of NPS-induced psychoses may help distinguish them from other psychotic disorders and guide tailored treatments.