Design by LF

University of Melbourne researchers are at the global forefront of investigating Hallucinogen Persisting Perception Disorder (HPPD), a visual condition triggered by psychedelic use. 

These scientists are in the preliminary stages of understanding the risk factors, causes, and potential treatments for HPPD, as much about the condition remains unknown. 

With psychedelic-assisted psychotherapy (PAP) in the early stages of roll-out across Australia and internationally, these researchers are aiming to improve patient screening for HPPD. 

This is especially important, as current evidence suggests individuals with existing mental health illnesses may at greater risk of developing HPPD.

While their is strong evidence that PAP can help treat various mental health conditions, frontline researchers stress the need for stronger risk safeguards. As conditions like HPPD serve as significant risks linked to PAP, as they remain under-researched and misunderstood. 

What is HPPD?

According to the Diagnostic and Statistical Manual, HPPD manifests in two ways: the first involves short episodes of psychedelic-like visual phenomena known colloquially as ‘flashbacks,’ while the second is characterised by persistent, daily visual disturbances. 

People with HPPD may experience visual snow, after-images, trails, geometric patterns, light sensitivity, and other visuals shaped by past psychedelic experiences.

To be clinically diagnosed with HPPD, these perception disturbances must be distressing and impairing to daily life. Although not all individuals find these perception changes particularly troubling, those who do often report experiencing anxiety, panic attacks, depression, and suicidal thoughts. 

Frequently, patients report a strong degree of isolation and loneliness, as if they’ve become stuck in a dream like world that non-suffers can’t relate to.  

Rare globally, higher risk among PAP patients

Though HPPD is rare, affecting about 1% of global users, Dr Jacob Paul, a cognitive neuroscientist at the University of Melbourne, told Farrago that those seeking PAP may face higher risk.

“Global prevalence is maybe not the most important thing here. And that's some of the things we're sort of nailing down… is that it's highly comorbid with these other mental health [issues] things.” 

“By definition, seeking out PAP to remediate anxiety, depression or PSTD, all are things that you might want to look at [for screening], they're already in the category of people who have a higher prevalence within those groups.” 

Dr Paul further highlighted that it isn’t a rarity that people, with some form of a pre-disposition for HPPD, enrolling into a psychedelic assisted therapy trail. 

“There's been definitely examples of people who have gotten, HPPD or HPPD-like symptoms from very early psych trials, which have been screened for literally everything else.” 

“So, does the person who signed up know that's what they're signing up for? if they're a visual artist, could that be the actual end of their ability to create their visual art?

National rising psychedelic use raises HPPD risk

The latest National Drug Strategy Household Survey, found that hallucinogen use in Australia has increased from 0.6% in 2007 to 2.4% of the population in 2022–‍2023 (roughly 500,000 people). 

Simultaneously, the number of patients receiving MDMA and Psilocybin through authorised and specialist psychiatrists is also progressively increasing as well. 

Dr Paul noted that with trends like micro-dossing Psilocybin on the rise, HPPD’s causes need greater attention. As there have been cases of people developing HPPD after micro-dossing, when visuals aren’t even experienced during the time of dosing. 

“It seems like there's just as many descriptions of HPPD occurring from, one large dose… and populations who are just microdosing.” 

This means that there's no concrete evidence that any particular dose is safe. The risk instead seems to vary greatly on individual factors that aren’t yet fully understood.

The University of Melbourne’s current work

With funding from advocacy group Perception Restoration Foundation, University of Melbourne researchers are developing an online psycho-physics screening tool to identify visual traits that may indicate HPPD risk.

While the tool is still in development Dr Paul highlighted that he hopes that the tool can function as an easily accessible option for individuals who are using or considering using psychedelics and for the current ongoing psychotherapy trials that don’t test for HPPD.

Dr Paul said they are starting with, “the broadest networking cast to begin with, and then from that, prune down and identify the things the best to try and get down to this very short, quick identifying screener.” 

The complex realities of Psychedelic assisted therapy

Farrago spoke to Sally Meikle, a PhD candidate at The University of Melbourne, about the broader implications of the growing focus on using Psychedelics to treat mental health conditions. 

Ms Meikle ran an open label clinical trial of psilocybin with psychotherapeutic support for treatment resistant depression with fellow researchers from Swinburne University. 

The trail involved seven participants with severe cases of treatment-resistant depression, that had persisted over multiple decades. 

“We did find a significant reduction in depression, which was great… but there was a really obvious amount of variation in how individual people responded to the treatment.” 

Ms Meikle explained that while two patients successfully went into long-term remission, three initially improved but later relapsed, and the remaining two didn’t have any positive response, with one actually getting worse.

“We had one participant in particular who had a really challenging dosing experience and then went on to develop quite severe anxiety that they hadn't experienced.”

“The thing is, I think it is so overhyped that it's this idea of a magic cure now, and the reality is, the majority of people didn't find any sustained benefit from the treatment.”

Meikle warned that there are some within the medicinal psychedelic space who are pushing for its full roll-out before properly considering the potential risks. 

“There's a weird sort of dichotomy in psychedelic research where a lot of people are really hyping it up and enthusiastic and downplaying all the risks. And then there's a few people that are trying to talk about the risks, who get sort of cast as like, oh, you're a naysayer and your anti-drug.”

“I think there are really substantial risks there, like prolonged psychological sort of difficulty in whether that's anxiety or the perceptual changes. I think if it's rolled out too fast, therapists don't have enough training, people aren't educated, you're going to see a huge increase in reports of adverse events.” 

While psychedelics may offer hope to those failed by traditional treatments, researchers at the University of Melbourne are working to ensure that hope doesn’t come at the expense of patient health, something that must remain central to the emerging wave of medicinal psychedelic therapy.