I hadn’t either. But for some reason, it’s been featured in two separate online news stories this week. Why now? Your guess is as good as mine. Here’s one:

What Is Hallucinogen Persisting Perception Disorder (HPPD)?

It’s considered rare — in the US, that means fewer than 200,000 cases — which makes sense, since it’s difficult to distinguish HPPD from more common conditions. Since it ordinarily follows on the heels of psychedelic drug use and its primary symptoms involve visual distortions, it’s likely to be misdiagnosed as substance-induced psychosis.

It isn’t. The other trademarks of a psychotic state — paranoia, delusions, disorganized thinking, and the rest — aren’t present.

The visual symptoms associated with HPPD can persist for weeks, months, or even longer. In practice, that translates to one (or sometimes more) of the following:

  • Trails: Objects in motion leave extended traces of light hanging in the air behind them.
  • Distorted colors: ordinary shades appear strangely vivid and intense. Bright splashes of color can appear unexpectedly.
  • Haloing: a glowing circle of light surrounds objects or people as you look at them.
  • Visual Snow: lines or patterns, usually geometric, that obscure images or objects in your field of vision.
  • Hallucinations: seeing objects or people who aren’t actually there.

These and other symptoms are typical of hallucinogen intoxication, but with HPPD, aren’t attributable to acute effects of the drug. A whole range of psychedelic substances can apparently trigger HPPD: LSD use of course, but also psilocybin, mescaline, MDMA, and the dissociative anesthetics ketamine and phencyclidine. Cannabis too, I’m told.

What’s causing HPPD? No one knows. Something’s obviously happening in the brain, but research is thin on the ground, and no widely accepted conclusions have been reached. Nor have explanations as to why it occurs in some people and not in others when both  used comparable doses of the same drug in the same place on the same occasion. One is left with memories while the other is gifted with a continuing light show. Merely unpleasant for some,  quite frightening for others.

As for treatment, there really isn’t one. Experts recommend sedatives or anti-epileptics for symptom relief, but I haven’t seen any data on how effective these are.

Hopefully the media interest will encourage more patients to self-identify HPPD, and we can begin to learn and hopefully, develop treatments.

I can imagine how annoying it must be for the patient, however.