The Effects of Ketamine on Cognition in Treatment-Resistant Depression: A Systematic Review and Priority Avenues for Future Research.
H. Gill, Barjot Gill, Nelson B Rodrigues, Orly Lipsitz, J. Rosenblat, Sabine El-Halabi, F. Nasri, R. Mansur, Yena Lee, R. Mcintyre
Neuroscience and Biobehavioral Reviews November 23, 2020 DOI: 10.1016/j.neubiorev.2020.11.020 via Semantic Scholar
Summary
About 40% of people with major depressive disorder have cognitive impairments, and those with treatment-resistant depression (TRD) often show such deficits. Ketamine, a rapid-acting antidepressant, may help. A systematic review of five studies found that a single low-dose intravenous infusion (0.5 mg/kg) did not worsen cognitive function. Some studies reported improvements in working memory and visual learning after ketamine treatment, while gains in processing speed and verbal learning occurred only in anxious TRD patients. The evidence suggests ketamine may have pro-cognitive effects in TRD, but more research is needed.
Study at a glance
| Characteristics | Systematic review Peer reviewed |
|---|---|
| Population | Patients with treatment-resistant depression |
| Keywords | Medicine Psychology |
| Citations | 92 |
| Key finding | A subanesthetic dose of IV ketamine does not worsen cognitive function and may improve working memory and visual learning in some patients with treatment-resistant depression. |
Abstract
Replicated evidence has documented cognitive deficits in populations with treatment-resistant depression (TRD). Approximately 40% of patients with MDD present with impairment of one or more cognitive domains. As such, there is an unmet need to discover treatments that have pro-cognitive effects in TRD patients. Ketamine has demonstrated efficacy as a rapid-onset intervention for the treatment of depression. The objective of the current review was to assess the effects of ketamine on cognition in TRD patients. We systematically searched the PubMed, Google Scholar and PsycINFO between database inception to March 24th, 2020. We identified five studies that evaluated cognition in TRD populations following ketamine treatment. All studies included a 0.5 mg/kg subanesthetic intravenous (IV) administration of ketamine. One study found significant improvements in complex (p = .008) and simple (p = .027) working memory and one study found improvements in visual learning memory following IV ketamine infusions (p = .014). Improvements in speed of processing and verbal learning memory were observed in anxious TRD participants only. Importantly, a subanesthetic dose of IV ketamine does not worsen cognitive function.