Ketamine, a medical anesthetic but also a favored recreational drug commonly known as ‘Special K’, has remarkable effects on people suffering from depression. According to Colleen Loo, a professor at the University of New South Wales in Australia who led a team that studied the drug’s effect on people over 60, depression symptoms were relieved in 43% of the patients. These effects lingered for six months after therapy, the authors reported last week in the American Journal of Geriatric Psychiatry.
However, despite these truly impressive results, many important questions remain unresolved. In an accompanying paper published in the journal Lancet, the same team led by Loo performed the first systematic review into the safety of ketamine use for depression and found the long-term risks are unclear.
The researchers looked at 288 peer-reviewed articles, of which 60 met the inclusion criteria. All in all, 899 patients who received at least one dose of ketamine were included into the review.
Whether administered orally, intravenously or snorted, ketamine produces several side effects. Among them, we can mention headache, dizziness, dissociation, elevated blood pressure and blurred vision.
The problem is that the present literature on ketamine for depression is severely lacking proper reporting of its side effects. The authors found that most studies only reported about ketamine’s side effects in an ad-hoc way and failed to track the long-term or cumulative effects of the drug.
“Despite low ketamine doses currently being used in depression studies, urological toxicity, liver function abnormalities, negative cognitive affects and risk of dependency may limit the safe use of ketamine as a long-term antidepressant treatment,” the authors state.
This is worrying because more and more studies report success in using ketamine for depression and more doctors are using the drug off-label for severe and treatment-resistant depression.
“As ketamine treatment will likely involve multiple and repeated doses over an extended time period, it is crucial to determine whether the potential side effects outweigh the benefits to ensure it is safe for this purpose,” Professor Loo said in a statement.
Previously, studies have linked the long-term use of ketamine to bladder inflammation, liver damage, cognitive changes like memory loss, and craving or addiction. However, these were just a few studies that had a fairly small sample size. Regarding addiction to ketamine, only 15 cases have been officially described in the scientific literature over the last 20 years. Does this mean that ketamine isn’t addictive? That’s the problem: we don’t know that much yet.
With this in mind, Loo cautions that more studies focused on assessing the safety of repeated dosing regimes for ketamine are urgently needed. His team is already at work devising a standardized tool that colleagues might want to use to address inconsistencies in the literature. Meanwhile, Loo and colleagues are also currently conducting the first ever independent trial for ketamine to treat depression, involving 200 participants who are followed after twice-weekly treatments.
The big takeaway is that long-term effects of ketamine are still largely unknown. There are side effects and we do know there are potential health risks. Ketamine is illegal in many countries but nevertheless, many people who have been battling with depression might feel encouraged by the news of ketamine’s effects to search for the drug on dark net marketplaces or on the streets. Perhaps, it’s wiser to wait.
Tibi is a science journalist and co-founder of ZME Science. He writes mainly about emerging tech, physics, climate, and space. In his spare time, Tibi likes to make weird music on his computer and groom felines.