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Updated: Jan 1, 2026
Brain Morphology of Cannabis Users With or Without Psychosis: A Pilot MRI Study
Published on: August 18, 2020
Acute Hippocampal Encephalopathy in Heavy Cannabis Users: About 2 Cases
Quang Tuan Rémy Nguyen1, Alban Gravier2, Constance Lesoil2
1Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor, service de Neurologie, Créteil, France; INSERM U955 Equipe E01, Institut Mondor de recherche biomédicale, Neuropsychologie Interventionnelle, Créteil, France; Département d'Etudes Cognitives, Ecole Normale Supérieure, PSL University, Paris, France; Université Paris Est, Faculté de Médecine, Créteil, France.
Background:
Cannabis use is increasing worldwide despite the various health effects of this substance.
Methods:
We report 2 cases of acute hippocampal encephalopathy in heavy cannabis users (>10 joints/d).
Results:
In both male patients, acute encephalitis was suspected. Brain magnetic resonance imaging (MRI) diffusion-weighted sequences showed bilateral high signal abnormalities in hippocampal regions. Patients had renal dysfunction, rhabdomyolysis, and inflammatory syndrome. Investigations showed no evidence of infectious or autoimmune encephalitides. Repeated electroencephalograms revealed no epileptic activity. Clinical, biological, and magnetic resonance imaging acute abnormalities improved within weeks. New exposure to cannabis yielded a new episode of encephalopathy. In both patients, severe long-lasting episodic memory impairment associated with hippocampal atrophy were observed several months later.
Conclusions:
Health professionals should be aware of this cannabis-related syndrome given its severe and long-lasting effects.
