Psychosis from Memantine

Psychosis represents one of the most severe adverse cognitive outcomes associated with psychoactive substance use. It is not a single symptom but a syndrome — a constellation of related disruptions to perception, belief, and thought that collectively produce a state in which the person has lost meaningful contact with shared reality. The defining features include delusions (fixed false beliefs maintained with absolute conviction),hallucinations (perceiving things that are not present, across any sensory modality),thought disorder (disorganized, incoherent, or tangential thinking and speech), andloss of insight (the inability to recognize that one's perceptions and beliefs are abnormal).

What distinguishes psychosis from the altered perceptions produced by a "normal" psychedelic or dissociative experience is fundamentally about insight. A person having a psychedelic trip may see geometric patterns overlay their visual field, but they know they have taken a substance and that the patterns are drug-induced. A person experiencing psychosis may see the same patterns but believe they represent coded messages from a government surveillance network — and no amount of rational argument can shake this conviction. The loss of the ability to reality-test one's own perceptions is the critical threshold that separates an altered state from a psychotic one.

Substance-induced psychosis can arise through several pathways. Acute intoxication psychosis can occur with high doses of psychedelics, stimulants, cannabis, and deliriants — the sheer intensity of the altered state overwhelms the person's capacity to maintain orientation.Stimulant psychosis is particularly well-documented: extended use of amphetamines, methamphetamine, or cocaine, especially combined with sleep deprivation, can produce a paranoid psychotic state that closely resembles acute schizophrenia, complete with persecutory delusions, auditory hallucinations, and disorganized behavior.Cannabis-induced psychosis can occur in predisposed individuals, sometimes after a single heavy exposure.Withdrawal psychosis can accompany withdrawal from alcohol and benzodiazepines.

The relationship between substance use and psychosis is bidirectional and complex. Substances can trigger psychotic episodes in individuals with latent vulnerability (genetic predisposition to schizophrenia-spectrum disorders), can worsen existing psychotic conditions, and can produce transient psychotic states in individuals with no underlying vulnerability. Cannabis use during adolescence has been identified as a significant risk factor for the later development of psychotic disorders, with a dose-response relationship. However, most people who use these substances never experience psychosis, and the interaction between substance exposure and individual vulnerability is not well enough understood to predict individual risk.

Harm reduction note: Psychosis is a psychiatric emergency. If someone has lost contact with reality — believing things that are clearly not true, acting on hallucinated perceptions, unable to recognize that they are intoxicated — they need professional help. Do not attempt to argue them out of delusions, as this typically escalates agitation. Ensure physical safety, speak calmly and simply, and call for medical assistance. Individuals with a personal or family history of psychotic disorders should exercise extreme caution with all psychoactive substances, particularly cannabis, psychedelics, and stimulants.