Study of Non-Invasive Deep Brain Stimulation With Low Intensity Focused Ultrasound Pulse (LIFUP) for Mild Cognitive Impairment (MCI) and Mild Alzheimer's Disease (AD)

Alzheimer disease (AD) is a neurodegenerative condition and the most common cause of dementia or a functional impairment in memory and other cognitive abilities. Prior to developing the functional impairment of dementia, patients develop mild cognitive impairment (MCI), which increases the risk for developing the functional impairment of dementia. Deep brain stimulation (DBS) is of interest as a potential therapeutic option for MCI and AD because it can directly target and modulate the activity of brain structures implicated in memory functioning.

Recently there have been multiple reports that DBS of different locations within the brain may be effective in improving symptoms characteristic of dementia (e.g., Heschman et al., 2013). For example, Laxton et al. (2010) performed DBS in the fornix/hypothalamus of six persons with AD in a phase I clinical trial. The investigators hypothesized that stimulation of the fornix would alter the activity of the medial temporal memory circuits, and thus delay and/or reverse memory loss. After 6-12 months, the investigators noted improvement or slowing in the progression of AD in some of the research participants, as measured by two commonly-used assessments of global cognitive function. In a recent literature review, Laxton et al. (2013) also described several additional studies demonstrating that DBS of the fornix or nucleus of Meynert or subthalamic nucleus influences the pathologic neurological circuits involved in AD.

Four separate groups recently have published reports concluding that ultrasound improves amyloid-β clearance in mouse models and restores memory (e.g., Leinenga & Götz, 2015). This finding raises the question of whether one method of DBS, Low Intensity Focused Ultrasound Pulse (LIFUP), could improve cognition in patients with AD, which is characterized by abnormal deposition of amyloid plaques in brain regions controlling memory and thinking. The use of LIFUP in animal models is well described (Bystritsky et al., 2014). LIFUP is able to penetrate the human skull and reach deep structures within the temporal therapeutic window. The structures that are reachable by LIFUP include the temporal cortices, hippocampus, thalamus, and subthalamic nuclei, all of which are implicated in the pathophysiology of AD. The Food and Drug Administration (FDA) recently approved an investigational device exemption (IDE) to begin a feasibility and safety trial of LIFUP for persons with refractory seizures.

Although symptomatic treatments are available for AD, their modest effects are temporary and there is a need for more effective interventions. In the current project, the investigators propose to use the FDA-approved protocol to:

1. Determine the feasibility of a brief LIFUP intervention (four stimulations of 30 seconds each, with 2-minute intervals between each treatment) for persons with MCI or mild (early-stage) AD.
2. As a secondary aim, the investigators will explore whether this brief LIFUP intervention is associated with improvements on neuropsychological measures of cognitive functioning immediately following the intervention.