A higher percentage of EEG vigilance stage A1, a measure of brain activity, is associated with response to intravenous ketamine in major depression. In a phase-2 randomized controlled trial of oral prolonged-release ketamine for treatment-resistant depression, no significant interaction between response and treatment was found for this EEG marker. However, a small-scale meta-analysis showed a significant pooled mean difference between ketamine responders and non-responders. Applying a previously proposed A1 cutoff of 43% yielded chance-level prediction accuracy in the combined ketamine group but 75% accuracy in the 240 mg subgroup. Responders to 240 mg ketamine also showed more stable vigilance over time. These findings support EEG vigilance as a predictive biomarker for treatment outcomes in depression, though further validation is needed.
Mindfulness training for primary care patients with anxiety or depression increased activity in the dorsal medial prefrontal cortex when anticipating pain, and this brain change was strongly linked to initiating health behavior changes. Greater increases in this brain response correlated with higher levels of action plan initiation, suggesting that mindfulness strengthens emotion regulation and goal-directed behavior in the face of discomfort.
In patients with treatment-resistant depression, higher baseline levels of magnetic substances in the right nucleus accumbens and the left amygdala, measured by brain imaging, predicted a greater reduction in specific depressive symptoms after repeated ketamine infusions. The study included 17 Japanese patients and used a double-blind, randomized placebo-controlled design followed by an open-label phase. Baseline magnetic susceptibility in the right nucleus accumbens correlated with improvement in retardation symptoms, while baseline R2* in the left amygdala correlated with improvement in vegetative symptoms. These brain markers may help predict which patients will benefit from ketamine treatment.