Co-existing neuropsychiatric symptoms (NPS) in patients with mild cognitive impairment (MCI), especially those worsening over time, are associated with more rapid cognitive and functional decline and a greater risk of Alzheimer's disease (AD). Optimal NPS management, meaning effectively managing multiple NPS simultaneously, requires a solid understanding of the shared neural mechanism across NPS. The goal of this proof-of-concept mechanistic intervention study is to validate the causal relationship between a NPS-shared neural circuit the investigators previously discovered and various NPS. The investigators will modify a key region within the NPS-shared neural circuit \[i.e. left precentral gyrus (LPG), critical for regulating visual attention\] with anodal transcranial direct current stimulation (tDCS). Our central hypothesis is that an activation of LPG and a reorganization of NPS-shared neural circuit will link to improvement in multiple NPS. Using a Stage 0 pilot randomized control trial design the investigators will recruit n = 40 older adults with informant-rated NPS that has worsened in the past 2 years, which is considered the most detrimental type of NPS in MCI. The investigators will assign participants to 4-week active anodal vs. sham LPG online tDCS group. The investigators will assess resting-state and visual attention task-related functional MRI and informant-rated NPS at baseline, and the end of week 4 and week 8, and diffusion MRI at baseline. The two primary aims are to determine the effect of tDCS on NPS-shared neural circuit (Aim 1), as well as the relationship between NPS-shared neural circuit and informant-report NPS (Aim 2). The exploratory aim will be to examine the relationship between NPS and the coherence between structural and functional aspects of the NPS-shared neural circuit. Probing the LPG via anodal tDCS provides a way to experimentally test the causal relationship between our previously discovered NPS-shared neural circuit and informant-rated NPS. The proposed research is highly innovative, while scientifically grounded, for targeting one brain region that may affect multiple NPS. Validating the hypotheses has the potential for future R01 study that directly conducts a Stage 2 trial addressing NPS in MCI, and thus ultimately improves patient's quality of life and reducing caregiving burden.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
40
tDCS (LPG/C3-anode, orbitofrontal cortex/Fp2-cathode) will be administered for 4 weeks (1 session per weekday for 2 weeks, and then 2 sessions per week for 2 weeks, for a total of 14 sessions). All subjects will receive anodal tDCS stimulation for 20 minutes per session, on C3 and the cathode electrode on Fp2 using 10/20 EEG system. tDCS will be applied with a pair of 35 cm2 single-use sponges soaked in approximately 4mL of saline solution on each side (\~8mL per sponge) connected to the stimulator. During the 20-minute tDCS session, we will use online tDCS design (i.e., a subject will simultaneously work on the visual attention-oriented task.
Cabin, Ur
Rochester, New York, United States
Change of C3 Activation (NPS-shared Neural Circuit Measure
Change of arbitrary unit LPG activation in response to visual attention task (measured using task related fMRI). No theoretical minimum or maximum exists for this scale.
Time frame: from baseline to post-intervention (4 weeks)
Change of C3 Connectivity (NPS-shared Neural Circuit Measure 21)
Change of arbitrary unit of correlation between LPG and amygdala at rest (resting fMRI). No theoretical minimum or maximum exists for this scale.
Time frame: from baseline to post-intervention (4 weeks)
Change of Patient-report NPS
Patient-reported NPS was measured using three mood-related questionnaires that probed mood within the past week: depression (Geriatric Depressive Scale ;GDS-30); anxiety (State-Trait-Anxiety-Inventory; STAI-state); and apathy (Apathy Evaluation Scale; AES). Total scores from individual measures were z-transformed (higher score indicating severer symptoms) across timepoints and averaged to create a composite mood score. A Z-score of 0 represents the population mean. Change of Z-score from baseline to post-intervention was used.
Time frame: from baseline to post-intervention (4 weeks)
Change of Informant-rated NPS
Informant-reported NPS was measured using the 12-domain Neuropsychiatric Inventory (NPI-Full), including both frequency and severity (based on present symptoms) during the past week. We first calculated the frequency x severity for each domain, then averaged across domains, and finally adjusted for caregiving burden. Higher is worse. We calculated the change of the arbitrary score from baseline to post-intervention. No theoretical minimum and maximum scores exist
Time frame: from baseline to post-intervention (4 weeks)
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