Researchers from the University of New South Wales and Macquarie University warn that psychedelic-assisted psychotherapy may activate visual imagination in people with aphantasia — a condition characterized by the absence of mental imagery — but at the same time increase the risk of intrusive thoughts and memories. The authors of the article, published in Cortex, call for more thorough patient education.

People with aphantasia are unable to visualize images, and their memories are less vivid and detailed. However, case reports, including a clinical account and preliminary data, indicate that even a single dose of ayahuasca or psilocybin can awaken the ability to visualize — with long-term effects suggested by patients’ testimonies lasting up to a year.

The issue is not only that suddenly emerging images may come as a surprise — they can also heighten emotional strain, especially if the imagery is distressing. The activation of visual imagination has been linked to an increased risk of post-traumatic flashbacks, depression, suicidal ideation, and intrusive memories.

Preliminary data from the lead author’s laboratory suggest that people with developed visual imagination are more prone to intrusive thoughts compared to those with aphantasia. It is also known that interventions such as playing Tetris can reduce post-traumatic stress symptoms, a phenomenon associated with the suppression of imagery.