In an open-label clinical trial, a single intravenous infusion of ketamine (0.5 mg/kg) was safe and well tolerated in 13 patients with mild cognitive impairment and major depressive disorder. No serious adverse events occurred. Depression severity, measured by the Montgomery-Asberg Depression Rating Scale, dropped from a mean of 27.4 before treatment to 5.7 at 24 hours after the infusion—a large-magnitude improvement. For 8 of the 13 patients, this improvement persisted for up to one month, with a mean score of 12.1 and at least a 50% reduction. These findings suggest ketamine may be effective for depression in this population, but larger randomized controlled trials are needed to confirm efficacy and assess cognitive effects.
Psychosis is a common and burdensome symptom in neurodegenerative diseases. Analyzing 283 autopsy-confirmed cases, delusions were linked to atrophy in the right temporal lobe and bilateral frontal lobes, especially when persecutory or paranoid, implicating circuits for reward, emotion, self-awareness, and executive function. Misidentification delusions correlated with right ventral temporal-occipital atrophy, disrupting visual stream processing. No consistent atrophy patterns emerged with hallucinations. Damage to these brain regions predisposes individuals to delusions across different syndromes and pathologies, suggesting shared mechanisms between neurologic and psychiatric disorders.