Hallucinations involve perceiving things that are not actually present, such as seeing, hearing, or feeling sensations that others do not. Paranoia is a state of intense suspicion and distrust of others, often accompanied by beliefs that others intend harm, even without evidence. Certain substances can significantly alter brain chemistry, leading to these experiences, which can range from mild perceptual distortions to severe breaks from reality. Understanding the types of drugs that induce these states and their underlying mechanisms is important for recognizing and addressing drug-induced psychosis.
Hallucinogenic Substances
Substances known for their hallucinogenic properties include classic psychedelics like lysergic acid diethylamide (LSD) and psilocybin, found in certain mushrooms. These drugs alter perception, mood, and thought processes, leading to vivid visual, auditory, and tactile hallucinations. While hallucinations are the primary effect, paranoia can also emerge, particularly in unfamiliar or stressful environments or with higher doses. These experiences, often called “trips,” can be highly unpredictable.
Dissociative drugs, such as phencyclidine (PCP) and ketamine, also induce hallucinations but operate through different mechanisms, often creating a sense of detachment from reality or the body. PCP, also known as “angel dust,” can lead to feelings of strength and invulnerability, alongside severe paranoia, agitation, and aggression. Ketamine, known as “Vitamin K” or “Special K,” can produce a profound sense of detachment, leading to a “K-hole” at high doses. Both PCP and ketamine can distort sight and sound, and cause anxiety and paranoia.
Stimulants and Their Effects
Stimulant drugs, including methamphetamine, cocaine, and high doses of prescription stimulants (e.g., Adderall), can induce paranoia and hallucinations. Chronic use or bingeing can lead to severe psychosis. Paranoia is common, with individuals often developing unfounded beliefs that they are being watched, followed, or targeted.
Hallucinations can be auditory, such as hearing voices, or tactile, like the sensation of insects crawling on or under the skin (formication). These effects are linked to prolonged use and neurochemical imbalances, particularly an excess of dopamine. High doses of prescription amphetamines, exceeding 30 milligrams of dextroamphetamine (equivalent to 40 mg of Adderall), increase the risk of new-onset psychosis or mania.
Cannabis and Synthetic Cannabinoids
Cannabis, especially high-potency strains, can induce hallucinations and paranoia, particularly in susceptible individuals or large quantities. Its psychoactive compound, delta-9-tetrahydrocannabinol (THC), interacts with the brain’s endocannabinoid system, which plays a role in mood, perception, and cognition. This interaction can disrupt brain function, leading to visual and auditory hallucinations, and heightened anxiety.
Synthetic cannabinoids, marketed as “Spice” or “K2,” are man-made chemicals sprayed onto plant material or sold in liquid form. These substances mimic the effects of THC but are significantly more potent and unpredictable. They can cause severe paranoia, extreme anxiety, confusion, and vivid hallucinations, often more intense and dangerous than those from natural cannabis.
Other Substances and Withdrawal Syndromes
Other substances and certain withdrawal states can also lead to hallucinations and paranoia. Anticholinergic drugs, which block acetylcholine in the brain, can cause profound confusion, disorientation, and vivid hallucinations, often described as “delirium.” Examples include scopolamine (for motion sickness) and high doses of some over-the-counter cold medications containing antihistamines like diphenhydramine. These medications can lead to agitated states.
High doses of corticosteroids, used to treat inflammation and autoimmune conditions, can induce psychiatric symptoms, including paranoia, delusions, and hallucinations. The risk increases with higher dosages and prolonged treatment. These effects relate to the steroids’ impact on brain chemistry, including dopamine activity.
Withdrawal from central nervous system depressants, such as alcohol and benzodiazepines, can trigger severe, life-threatening conditions characterized by hallucinations and paranoia. Alcohol withdrawal, particularly delirium tremens (DTs), can cause intense confusion, agitation, visual and auditory hallucinations, and paranoia. Abrupt cessation of benzodiazepines can also lead to withdrawal psychosis, with symptoms including confusion, delusions, and hallucinations, as the brain struggles to rebalance its neurochemistry.
Underlying Mechanisms of Drug-Induced Psychosis
Drug-induced hallucinations and paranoia often stem from a disruption in the brain’s neurochemical balance. Many psychoactive substances directly influence neurotransmitters, the chemical messengers that transmit signals between nerve cells. A common pathway involves the dopamine system, where excessive dopamine activity in certain brain regions is linked to psychotic symptoms like hallucinations and delusions. Drugs that increase dopamine levels, such as stimulants, can precipitate or worsen psychosis.
Serotonin pathways are also implicated, particularly with hallucinogenic drugs that alter serotonin receptor activity, leading to distortions in perception and thought. Beyond individual neurotransmitters, drugs can disrupt complex brain networks responsible for integrating sensory information and testing reality. This interference can lead to misinterpretations of sensory input, resulting in hallucinations, and affect judgment and reasoning, contributing to paranoid ideation. Individual vulnerability, influenced by genetic factors or pre-existing mental health conditions, can increase the likelihood of experiencing these effects when exposed to certain substances.