Single Ketamine Infusion and Neurocognitive Performance in Bipolar Depression

This open-label study (n=18) assessed antidepressant efficacy and neurocognitive performance of intravenous ketamine (35mg/70kg) in patients with bipolar depression (BD) and found that around half the patients responded to treatment. Independent of depressive symptoms, ketamine generally improved impairments in their cognitive performance, on measures related to psychomotor speed, verbal abilities, and executive functioning.

Abstract

“Methods: We estimated neurocognitive performance using the trail making test (TMT) and the Stroop color-word interference test before, and on the 3^rd day after a single infusion of ketamine, in 18 bipolar depressed patients receiving mood-stabilizing drugs.

Results: The performance on all tests significantly improved on the 3^rd day after ketamine infusion which correlated positively with baseline intensity of neuropsychological impairment and was not associated either with baseline intensity of depression or reduction of depressive symptoms after 3 or 7 days.

Discussion: The results suggest that in such population of patients, single ketamine infusion may improve neuropsychological performance independently of antidepressant effect.”

Authors: A. Permoda-Osip, J. Kisielewski, A. Bartkowska-Sniatkowska & J. K. Rybakowski

Summary

Researchers measured neurocognitive performance before and after a single ketamine infusion in bipolar depressed patients receiving a mood stabilizing drug and correlated this with the antidepressant effect of such a procedure.

The study comprised 18 in-patients with bipolar mood disorder, aged 27-67 (mean 50-11) years, who were receiving mood-stabilizing medications of the first or/and second generation. A single intravenous ketamine infusion (0.5 mg/kg body weight) was performed between 8:00 – 8:45 h.

Patients were included if their baseline intensity of depression was not less than 18 points on the Hamilton Depression Rating Scale.

The following neurocognitive tests were used: the trail making test (TMT), the Stroop color-word interference test (RNCb), and the Stroop color-word discrimination test (RNCd). All patients gave their informed consent after the nature of the procedures had been fully explained to them.

Neurocognitive performance was significantly improved on the 3rd day after ketamine infusion compared with baseline. There was no correlation between improvement and depression intensity or reduction after 3 or 7 days.

In bipolar patients receiving mood-stabilizing drugs, a single infusion of sub-anaesthetic doses of ketamine improved neuropsychological performance on the 3rd day after infusion. This improvement was independent of the antidepressant action of ketamine.

We observed improvement in some neurocognitive functions in patients with treatment-resistant major depression after serial ketamine infusions, which was associated with worse results on some tests at baseline.