Flashbacks
Flashbacks are vivid, spontaneous re-experiences of past events, often involving sensory or emotional elements, and are typically linked to previous psychedelic drug use or severe trauma. These experiences can manifest as acute flashbacks, which are short-lived and can be either pleasant or disturbing, or as chronic flashbacks, associated with hallucinogen persisting perception disorder (HPPD). HPPD is characterized by frequent, intrusive flashbacks that can disrupt daily life and alter one’s perception of reality.
While psychedelic substances like LSD and psilocybin are commonly associated with flashbacks, trauma-related flashbacks can occur in individuals who have experienced significant psychological distress, such as combat veterans or victims of violence, and are often seen in those diagnosed with post-traumatic stress disorder (PTSD). The exact causes of flashbacks remain unclear, with various theories suggesting that they might be related to the storage of drugs in body fat, potential brain damage, or altered states of consciousness.
Triggers for flashbacks include stress, fatigue, and certain substances, while treatment options vary and may include medications, psychotherapy, and lifestyle modifications. Although no definitive treatment exists, ongoing research continues to explore effective methods for managing flashbacks and HPPD.
Flashbacks
ALSO KNOWN AS: Déjà vu; hallucinogen persisting perception disorder
DEFINITION: Flashbacks are spontaneous, vivid, sensory (usually visual) or emotional re-experiences, often associated with the past use of psychedelic drugs, such as LSD, or with past severe trauma.
Acute Flashbacks
Acute flashbacks are sensory or emotional experiences in which a person relives a past event or experience. Most flashbacks are spontaneous and triggered by a particular sight, sound, or smell. The person undergoing a flashback recalls sounds, smells, images, and feelings that are often more vivid than during the original event or experience. Acute flashbacks are unexpected and short-lasting. In most cases, they are benign, pleasant, and even comforting. In some cases, however, they are disturbing and can lead to psychotic episodes, severe depression, or schizophrenia.
Chronic Flashbacks
Hallucinogen persisting perception disorder (HPPD) is a chronic condition in which recurring flashbacks interfere with a person’s daily life. In mild cases, flashbacks occur infrequently. In extreme cases, flashbacks occur regularly and begin to distort a person’s perception of reality. HPPD is associated with the use of hallucinogenic drugs. Flashbacks can occur at any time, from a day to a year or years after taking a hallucinogen.
HPPD flashbacks cause visual disturbances. The person suffering from HPPD may see flashes of intense color; auras around people’s heads; dancing geometric shapes; images trailing moving objects; positive afterimages, in which objects remain in the brain after they have left the field of vision; or distortions in which objects appear larger or smaller than they are in actuality.
Trauma-related Flashbacks
Trauma-related, or nondrug-related, flashbacks were first described medically by doctors treating World War I combat veterans. These types of flashbacks are seen not only in combat veterans, but they are also seen in other people who have experienced severe trauma, such as witnessing violent death or being the victim of a criminal act. Flashbacks affect many persons with post-traumatic stress disorder (PTSD).
Drug-related Flashbacks
Hallucinogens are the drugs most associated with flashbacks. LSD (lysergic acid diethylamide, or acid); psilocybin in certain mushrooms; and PCP (phencyclidine, or angel dust), originally an anesthetic, are the main hallucinogenic, or psychedelic, drugs. By far, LSD is the most commonly used and studied psychedelic.
During LSD flashbacks, users experience an abbreviated version of an earlier drug trip, or experience, without taking the drug. Many users report that the flashbacks are even more intense than the original trips. The flashbacks can be isolated or recurring, brief or drawn-out, pleasant or disturbing, and benign or damaging. Because LSD flashbacks usually appear suddenly, without warning, they can disrupt a person’s daily routine and lead to unpredictable behavior.
Chronic LSD users are more prone to flashbacks than occasional users. People with an underlying emotional problem and people highly susceptible to suggestion also are more prone to flashbacks than healthy users. Even emotionally healthy people who have used LSD only once or twice can experience flashbacks more than one year after taking the drug.
Causes
Scientists do not fully understand the biochemical processes through which hallucinogens affect the mind and body, and they do not know the causes of LSD flashbacks and HPPD. Research suggests several theories for flashbacks.
First, drugs can remain stored in body fat and some organs—lungs, kidneys, liver, and brain—long after they are taken. When the body burns fat during strenuous activity, the drugs might enter the bloodstream, causing the person to experience some of the drug’s effects. Second, LSD might have damaged the brain, causing it to send incorrect signals. Third, LSD may have changed the way the brain functions and processes information, which may account for the accompanying visual disturbances. Another theory holds that flashbacks have nothing to do with psychedelic drugs but that flashbacks are naturally occurring altered states of consciousness that are not understood and, consequently, mislabeled or misinterpreted by drug users.
Triggers
Although scientists do not know the causes of flashbacks, they are reasonably sure of specific triggers. Common flashback triggers include physical or mental stress; physical or mental fatigue; lack of sleep; marijuana or alcohol binging; the use of certain prescription drugs, including antidepressants; and mild sensory deprivation. People sometimes deliberately induce mild sensory deprivation to alter their consciousness or to relax deeply. To induce mild sensory deprivation, a person might focus intensely on one sound, blocking out all other background sounds, or stare at a solid-colored surface without blinking for an extended period.
Treatment
No specific treatment exists for flashbacks, but several options are available to patients. Doctors have prescribed certain medications, such as antiseizure and antiepileptic drugs, for people suffering HPPD. However, the effectiveness of these drugs remains debatable because of the unpredictability of flashbacks and because of the uncertainty of their cause. Benzodiazepines, clonidine, Naltrexone, antipsychotics, and selective serotonin reuptake inhibitors (SSRIs) have also been used to treat HPPD. Treatment for trauma-related flashbacks generally follows the protocols for treating mild mental disorders: talk therapy or other forms of psychotherapy. Repetitive Transcranial Magnetic Stimulation (rTMS) has shown promise in treating HPPD, although more study is needed. Lifestyle changes have also been suggested. A 2022 study using valproic acid and prazosin suggests possible treatment options, but the authors called for further study.
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