Serum copper concentration changes during ketamine treatment in patients with treatment-resistant depression, but no clear link between copper levels and treatment response was found. Patients with major depressive or bipolar disorder received weekly ketamine infusions, and copper levels were measured before, during, and after treatment. Copper concentration was significantly higher before treatment than after the fifth infusion, and also higher after the full course than after the fifth infusion. However, changes in copper levels did not correlate with scores on depression or mania rating scales, nor with somatic comorbidities. The findings provide data on copper's role in short-term ketamine therapy but do not support copper as a marker of treatment response.
A systematic review of five studies involving 678 participants examined how ketamine treatment affects appetite in people with treatment-resistant mood disorders. Two studies found significant improvement in reduced appetite after ketamine or esketamine treatment; one found no significant change; one reported a paradoxical worsening; and one noted minimal effect on increased appetite and atypical symptoms. The evidence suggests ketamine may improve depressive symptoms including appetite, or have neutral effects. Measuring appetite could help detect antidepressant effects beyond traditional medications and aid treatment planning for patients with metabolic disorders or malnutrition risk.
Impulsive behaviors are common in major depressive disorder and bipolar disorder, raising suicide risk and mood instability. Ketamine, an NMDA receptor antagonist, can produce rapid antidepressant and antisuicidal effects, and magnesium given with low-dose NMDA antagonists reduces anxiety- and depression-like behaviors in animals. This observational study of 49 inpatients with treatment-resistant mood disorders measured impulsivity with the Barratt Impulsiveness Scale (BIS-11) and magnesium levels before and during a four-week course of eight ketamine infusions. Magnesium ion concentration during treatment was not associated with changes in BIS-11 scores. The findings provide no evidence for a relationship between magnesium levels and impulsivity during ketamine therapy.