Persistent Amotivation After Cannabis-Related Psychosis: Diagnostic Challenges and Clinical Course With Electroconvulsive Therapy: A Case Report

Cannabis use may cause psychotic symptoms, such as hallucinations and delusions, as well as persistent amotivation with reduced motivation, inactivity, and cognitive impairment. Although described as cannabis-related amotivational syndrome, it is not recognized as an independent diagnostic entity and overlaps clinically with the negative symptoms of schizophrenia and mood disorders. We report a case of persistent amotivation following cannabis-related psychosis that improved after electroconvulsive therapy (ECT).

A 19-year-old man developed auditory hallucinations, persecutory delusions, and agitation associated with cannabis use and was admitted to a psychiatric hospital. Antipsychotic treatment improved the psychotic symptoms, but marked amotivation and inactivity, accompanied by low performance on cognitive screening, and significantly impaired daily functioning. Depressed mood and appetite loss were not evident. Although negative symptoms of schizophrenia remained a differential diagnosis, the presentation was consistent with cannabis-related amotivational syndrome. Amantadine produced limited improvement. Following ECT, the Apathy Scale score improved from 24 to 7 and the Mini-Mental State Examination score increased from 19 to 26, with improvements in motivation, activity, and daily functioning.

This case demonstrates that clinically significant amotivation may persist after cannabis-related psychotic symptoms improve. Persistently reduced motivation and inactivity should not be assumed to represent primary negative symptoms of schizophrenia; rather, clinicians should carefully consider mood symptoms and cannabis-related amotivation in the differential diagnosis. This case also suggests that ECT may represent a treatment option for severe, persistent amotivation following cannabis-related psychosis. However, because this was a single case, further validation through additional cases and long-term follow-up is required.