Ketamine, a medication used for depression, may also reduce anhedonia (loss of interest or pleasure). A systematic review of 22 studies (4 randomized-controlled trials and 18 open-label trials) found that all reported alleviation of anhedonia symptoms after ketamine or esketamine administration, regardless of the number of infusions. Neuroimaging studies showed changes in functional connectivity linked to improvement. However, limitations include few placebo-controlled trials. The review suggests a potential anti-anhedonic effect of ketamine in depressed patients, likely through neuroplastic changes.
Intravenous ketamine at 0.5-1.0 mg/kg based on actual body weight is effective for treatment-resistant depression. In a retrospective analysis of 28 inpatients with treatment-resistant major depressive disorder, alternative dosing formulas using lean body mass, ideal body weight, or body surface area generally led to underdosing compared to the standard 0.5 mg/kg dose. Only two participants received higher doses when using the Devine formula. The findings suggest that alternative dosing methods may reduce treatment response and complicate outcome interpretation. Future studies should incorporate direct body composition measures like bioimpedance and waist-to-hip ratio.