A systematic review of medical research has shown that ketamine and esketamine show no adverse cognitive effects in treatment-resistant depression.
The review of medical research has shown that both ketamine and esketamine have no adverse effects on memory, attention or other cognitive processes. According to the findings, some cognitive functions improved seven to 13 days after repeated ketamine infusions.
The review has been published in the Harvard Review of Psychiatry.
Cognitive safety
Ketamine, which is a widely used surgical anaesthetic, has been shown to have rapid antidepressant effects at low doses, and esketamine, a variation of the drug, has recently been approved for depression treatment. Although ketamine is not yet approved for treatment of depression, some physicians prescribe it for the condition on an “off-label” basis.
Despite offering promise as a treatment, there are potential safety concerns with ketamine such as memory impairment after long-term recreational use of ketamine, as well as in medical studies in which healthy volunteers received just one infusion. Such problems, and other cognitive symptoms, are a key aspect of major depressive disorder.
According to the new research, led by Breno Souza-Marques, BA, and Lucas C. Quarantini, MD, PhD, of Federal University of Bahia, Salvador, Brazil: “Current evidence suggests that ketamine and esketamine do not appear to exert significant deleterious neurocognitive effects in treatment-resistant depression.”
For the review, 14 studies were identified that collectively involved 1,019 patients: one study of esketamine nasal spray for 44 weeks, seven studies of a single ketamine intravenous infusion, and six studies in which patients received six ketamine infusions over two or three weeks.
The esketamine study showed no changes in cognitive performance, where as five studies of ketamine reported improvements in memory, processing speed, or cognitive flexibility. Only one of the 14 studies reported cognitive impairment after ketamine treatment.
Memory was worse 24 hours after six ketamine infusions, and processing speed was worse 24 hours after a single infusion, but these deficits were no longer present seven days after treatment.
The researchers noted: “Results suggest possible neuropsychological profiles predictive of antidepressant response to ketamine, such as lower attention, slower processing speed, or higher working memory, that should be further assessed in future studies, as these results could provide time-saving evidence to clinicians and mental health practitioners.”
The review highlights that, despite this encouraging evidence, further studies are needed to assess the longer-term neurocognitive effects of the drugs.
