“Since physicians are largely unfamiliar with the diagnosis, the condition is probably underreported.”

– Dr. Henry Abraham

The critical point to be made about HPPD is to dispel the myth that is is rare. The only study ever having been done quantifying the frequency of HPPD among drug users was drafted and conducted by Dr. Matthew Baggot; PhD, Berkeley. According to the survey study, about 4% of recreational drug users experience HPPD-like symptoms (Baggott MJ, et al. Abnormal visual experiences in individuals with histories of hallucinogen use: a web-based questionnaire. Drug Alcohol Depend. 2011 Mar 1; 114(1):61-67).

According to the 2013 National Household Survey on Drug Abuse (NHSDA), an estimated 1.3 million persons aged 12 or older (0.5 percent) used hallucinogenic drugs within the past month. Among 18 to 25 year olds in 2013, the rate of current use of hallucinogens was 1.8 percent. First-time users aged 12 or older numbered 1.1 million persons. The incidence of first-time hallucinogen use has exhibited two prominent peaks of increase: 1) From 1965-1969 there was a marked increase predominately in the use of LSD, and 2) from 1992-2000 there was a marked increase predominately from use of MDMA. However, hallucinogens continue to be among the most frequently abused class of drugs in high school students, after alcohol and marijuana.

In taking that percentage and running the numbers of drug users as seen in this 2013 study (the only one of its kind provided by the NIH):

The study purports that hundreds of thousands of children under 12 years old nationally have experimented with hallucinogenic drugs on a monthly basis which statistically makes it impossible for HPPD to be uncommon; in fact there are probably thousands upon thousands of cases that are misdiagnosed as most physicians do not understand what HPPD is, let alone how to treat it.

Race, sex, and age-related demographics

Within the United States, hallucinogen use is most common amongst non-Hispanic whites. There is also a high life-time prevalence rate of hallucinogen use among American Indian and Alaska Natives. Hallucinogens are abused most frequently by males. The highest rate of hallucinogen abuse occurs in persons aged 18-25 years.