Single-dose Ketamine Treatment to Improve Depression in Mild Cognitive Impairment

Ketamine is a rapid-acting antidepressant thought to work, at least in part, by the enhancement of neural plasticity and the growth of new synapses. A single dose of ketamine has been shown to improve depression and cognition with short-term memory, inhibitory control, cognitive flexibility, and processing speed showing improvements within days of treatment. The mechanism behind ketamine's rapid action is not clear but some groups have speculated it may be related to enhanced neuroplasticity, particularly in the frontal areas and the hippocampus. If this mechanism is accurate, ketamine may be especially effective in treating individuals with mild cognitive impairment and depression (MCI-D) where changes in the hippocampus and frontal areas have been implicated. Although few studies have been published on the effects of ketamine in older adults, they suggest that ketamine treatment might be effective in improving depression in older adults and relatively safe. There are no studies looking at the effects of ketamine treatment in patients with MCI-D. A key hypothesis of this study is that IV ketamine treatment will be well-tolerated and will improve depression and cognition in patients with MCI-D. The effects of brain imaging and activity abnormalities and amyloid biomarker status on the responsiveness to ketamine will be explored. This open-label pilot study is designed to gather data to support an application for a larger NIH-funded study. This study is an open-label trial to determine the safety and tolerability of a single sub-anesthetic (0.5 mg/kg) intravenous (IV) ketamine treatment in individuals with mild cognitive impairment and depression (MCI-D). As secondary endpoints, whether treatment with a single dose of ketamine may improve mood or cognition in individuals with MCI-D will be examined. In exploratory analyses, whether AD biomarker status has any influence on the effectiveness of ketamine treatment in MCI and brain connectivity changes after ketamine treatment will be examined. The entire study period will be approximately 1 month from start to finish. The study begins with screening followed by a baseline visit. Then there will be a single visit where an infusion of 0.5 mg/kg of IV ketamine will be performed. There will be follow-up visits 1 day, 2 days, 3 days, 7 days, and one month after the infusion. Baseline visit will include questionnaires, blood draw, cognitive evaluation, clinical evaluation, neuroimaging (specifically a non-contrast magnetic resonance image (MRI)), and an optional electroencephalogram (EEG). Follow-ups will include questionnaires, cognitive evaluation, and clinical evaluation. Additionally, blood draw and imaging (MRI) follow-up may be performed.