At low concentrations (much lower than those needed to bring about anesthesia), ketamine offers promise for addressing treatment-resistant depression. This effect is likely due to ketamine’s action on a protein called brain-derived neurotrophic factor (BDNF) in the hippocampus [16]. The subacute and long-term dosing of ketamine on a daily basis has also been shown to reverse the cognitive dysfunction caused by chronic mild stress, while also offering antidepressant and anxiolytic (anxiety-reducing) effects [17]. Although these studies were carried out in rats, they show the potential therapeutic value of ketamine microdosing to enhance cognitive health.