Which of the following is a documented effect of hallucinogen abuse?

Hallucinogen abuse is associated with a range of psychological effects, and one of the well-documented phenomena is the occurrence of flashbacks. Flashbacks are spontaneous recurrences of the experience of hallucinations that can occur long after the drug has worn off. They can happen days, weeks, or even months after ingestion and can be triggered by stress, fatigue, or drug use. This effect relates to how hallucinogens impact the brain's perception and can leave lasting impressions or alterations in sensory processing.

While other options suggest beneficial effects such as increased stamina, heightened memory recall, or improved focus, these are not typically associated with hallucinogens. Instead, the drug's effects tend to impair cognitive functions, create distortions in perception, and lead to unpredictable psychological experiences. As such, flashbacks stand out as a significant and troubling consequence of hallucinogen use.