When the Trip Never Ends


by Dirk Hanson

April 29, 2013

After taking a dose of mescaline in 1898, the writer Havelock Ellis reported that he experienced a heightened sensitization to “the more delicate phenomena of light and shade and color” for a prolonged period after the drug experience. This may represent the first description of what came to be known as a hallucinogenic “flashback.”

For years, LSD users have described the occasional spontaneous return of LSD-like sensory effects, including visual disturbances. These episodes are typically transient and non-threatening. However, a subset of LSD users—as well as users of MDMA, known as Ecstasy—find themselves hobbled by continual visual distortions long after their last experience with hallucinogens.

Unlike flashbacks, Hallucinogen Persisting Perception Disorder (HPPD), as it’s known in the DSM-IV, does not abate for months or years, if ever, and can cause considerable anxiety and panic in those who experience it. It also can seriously interfere with reading, driving, and other aspects of normal life.

Persistent flashbacks of the HPPD variety may represent permanent neural disruptions due to “disinhibition of visual processing related to a loss of serotonin receptors on inhibitory interneurons,” says Henry Abraham, a lecturer in psychiatry at Tufts University School of Medicine in Boston who has published several papers on HPPD.

Reports of the spontaneous appearance of LSD-like phenomena in former users date back to the late 1950s, but Abraham was the first investigator to give the disorder wide prominence with his 1983 paper, “Visual Phenomenology of the LSD Flashback,” published in the Archives of General Psychiatry. At Massachusetts General Hospital in Boston, Abraham documented a syndrome of disordered perception with distinct diagnostic features in 123 people who had used LSD in the past. Half of his subjects had been suffering from visual distortions and other problems for more than five years since their last LSD experience.

What do people with HPPD report seeing? Becoming aware of bright spots before your eyes when entering a dark room does not count as HPPD, for example. Nor is HPPD the same thing as floaters, those watery patches that seem to glide across one’s field of vision from time to time. For some of Abraham’s study participants, the text on a book page jumped and flashed—“a bichromatic alphabet soup of images,” as he put it. Confusing geometric phosphenes blossomed and billowed beneath closed eyes. Trailing phenomena—the much-parodied “tracers,” where a hand waved slowly in front of the eyes produces a trail of images like stuttering film frames—plagued some participants ceaselessly. Objects appeared to be surrounded by halos or mist, and afterimages complicated people’s color vision. These altered perceptions can be mild or severe, but in all cases, HPPD subjects were fully aware of the unreality of their visual illusions. Such visual disturbances, Abraham concluded, are “mediated centrally, and not only in the retina.”

 “The occipital cortex and the non-dominant temporal lobe showed disinhibition, and also greater spectral coherence,” Abraham says. “If you start to have a seizure in an area of the brain, other areas near it begin beating in exactly the same rhythm. That’s coherence. The HPPD people had increased coherence in the parts of the brain that govern visual information processing. In other words, it was like pre-seizure activity.”

 Work by Abraham and others has also shown that people with HPPD are less able to discriminate between colors and less sensitive to strobing lights. In the latter case, Abraham has shown that people with HPPD “see a flickering light as fused more often than non-users, because the eyes of the LSD user continue to see the light after it’s gone.” Others see a continual screen of TV-like “snow.” Moreover, people with HPPD are often photosensitive—light acts as a trigger for their symptoms.

A pre-existing condition?

According to John Halpern and Harrison Pope of the Biological Psychiatry Laboratory at Harvard Medical School, writing in Drug and Alcohol Dependence, “there is probably something different in the visual cortex of these individuals that pre-dates use of an hallucinogen.” Abraham agrees, noting that his group “confirmed that there was a peak at around 10 trips, and then there was another peak at around 50 trips, and then sort of a flat plateau afterwards. This trimodal distribution is possibly explained by the distribution of an autosomal recessive gene governing sensitivity to the effects of hallucinogens.”

 HPPD is often linked with Post Traumatic Stress Disorder; the two condition share symptoms such as anxiety, panic, and distorted perceptual effects. In their study, Halpern and Pope caution that clinicians must first eliminate PTSD, epilepsies, migraine, schizophrenia, depersonalization, and other disorders before making a diagnosis of HPPD.

Keith Laws, professor of cognitive neuropsychology at the University of Hertfordshire in the UK, calls visual hallucinations the “ugly sister” in terms of psychological research priorities. Laws, who was not involved in the studies, said that visual illusions similar to HPPD can occur in a range of pathologies, from Parkinson’s disease to dementia to damage in the V5 visual cortex area following carbon monoxide poisoning. “However visual hallucinations are caused, they are always extremely disturbing and in many cases require additional psychiatric help,” says Laws. “We should be researching this much more than we do.”

It was not until 1986 that HPPD was given a formal diagnosis, in the DSM-III-R. And even today, little is known about key features of the disorder. Abraham refers to it as an “orphan science.” How common is HPPD? Since physicians are largely unfamiliar with the diagnosis, the condition is probably underreported. “We found that the average HPPD patient has to see six different doctors before they get a diagnosis,” says Abraham.

Abraham says he is in general agreement with the results of a survey by EROWID, an online drug information site, which found that about 4% of LSD/MDMA users reported experiencing symptoms of HPPD. This is a substantial number, given the baby boomers’ propensity for experimenting with LSD and the Gen X fondness for Ecstasy. Why haven’t former users suffering from HPPD been appearing in droves at doctors’ offices and psychiatric clinics? Shame, stigma, fear, and embarrassment might be making them reluctant to seek help, says Abraham.

Are there effective treatments? First you need a diagnosis, and many HPPD patients complain that they are often met with skepticism by health professionals when they seek medical or psychiatric aid. But there are two different benzodiazepines used as anticonvulsants, Clonazepam and Midazolam, that have shown promise for mitigating HPPD symptoms. In a 2005 drug trial, Levetiracetam, a medication used for epilepsy, also performed well. However, anti-psychotic drugs like risperidone can dramatically worsen symptoms, so HPPD patients wrongly diagnosed as delusional may get exactly the wrong kind of medication for their condition. As with many chronic conditions, such as alcoholism and tinnitus, counseling and therapy often become the predominant forms of treatment.

Common triggers for HPPD symptoms include fatigue, marijuana, and alcohol. “Marijuana is probably the worst,” says Abraham. “For this population, it’s absolutely contraindicated. This is the kind of thing a doctor needs to tell them.”

 David Kozin, who has HPPD, researched the disorder at Harvard Medical School as an undergrad and maintains the largest HPPD community support site on the Internet at http://hppdonline.com. Kozin provides a memorable description of his HPPD symptoms: “I look at my computer monitor and the beige plastic starts turning pink…. The clothes in the open closet are swaying back and forth. Add to this a layer of static and a visual imprint of the path my arm took on its way to grab some iced tea…. I realize none of these odd visual perceptions is real.”

Abraham remains optimistic: “There are co-morbid illnesses that HPPD people have that we can treat. They have serious anxiety disorders. Almost half of them have serious depression. For some people, this is a lifelong process.”