The goal is to determine whether three months of at least three times / week of sensory flicker stimulation improves cognition, mobility, and affect in older adults with Subjective Cognitive Decline (SCD), relative to an SCD control group receiving white noise sensory stimulation. Investigators will also determine whether the intervention slows cortical thinning and declines in brain functional network segregation and changes in blood biomarkers of Alzheimer's Disease (AD).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
60
Investigators will combine ultrasound (≥22 kHz) and near-infrared two-photon stimulation (890-940 nm) to deliver rhythmic input in a subliminal, comfortable manner, without the side effects associated with visible flicker.
The control group will receive white noise sensory stimulation rather than a constant flicker frequency.
University of Florida
Gainesville, Florida, United States
Cognition
Investigators will comprehensively assess behavior at three times (baseline, half-way through (1.5 months), and after the intervention (3months)) using the NIH Toolbox. Composite Scores of Fluid Cognition from the Cognition Toolbox will serve as primary metrics for cognition.
Time frame: Baseline, halfway through (1.5 months), and post-intervention (3 months)
Grip strength
Participants will grip a machine which measures their grip strength in kg.
Time frame: Baseline, halfway through (1.5 months), and post-intervention (3 months)
10m Gait Speed
Participants will walk unassisted for 10 meters. Their speed will be measured in seconds.
Time frame: Baseline, halfway through (1.5 months), and post-intervention (3 months)
Clinical Test of Sensory Interaction on Balance (CTSIB)
Participants will, with eyes open and closed, walk on rough and smooth terrain. Investigators will measure sway area (measured in m\^2/s\^4).
Time frame: Baseline, halfway through (1.5 months), and post-intervention (3 months)
Affect - POMS-2
This test is used to assess transient feelings and mood among individuals aged 13 years and above. Scoring: 0 - Not at all 1. \- A little 2. \- Moderately 3. \- Quite a Lot 4. \- Extremely Except "Relaxed" and "Efficient", and they score the reverse:
Time frame: Baseline, halfway through (1.5 months), and post-intervention (3 months)
Affect - Ryff Scales of Psychological Wellbeing
Respondents agree or disagree with 42 statements using a 6-point scale (1 = strongly agree; 6 = strongly disagree).
Time frame: Baseline, halfway through (1.5 months), and post-intervention (3 months)
Affect - Satisfaction with Life Scale
The possible range of scores is 5-35. Scores between 5-9 indicate the respondent is extremely dissatisfied with life, whereas scores between 31-35 indicate the respondent is extremely satisfied.
Time frame: Baseline, halfway through (1.5 months), and post-intervention (3 months)
Affect - Perceived Stress Scale
Score is obtained by reverse-scoring items 4, 5, 7, and 8 and then summing the scores.
Time frame: Baseline, halfway through (1.5 months), and post-intervention (3 months)
Affect - Apathy Evaluation Scale
After recoding all necessary items, sum up all scores.
Time frame: Baseline, halfway through (1.5 months), and post-intervention (3 months)
Brain Structure and Network Function
Investigators will assess brain structure via a T1 MRI to measure cortical thickness in dorsolateral prefrontal, sensorimotor, and insular cortices using the CAT computational anatomy toolbox; brain network function via resting-state fMRI to capture functional segregation of dorsolateral prefrontal, sensorimotor, and insular networks (subserving cognition, mobility, and affect respectively) using the CONN toolbox.
Time frame: Baseline, and post-intervention (3 months)
Blood-based AD pathology (Aβ17)
Investigators will assess levels of Aβ17 \[units\], which is sensitive to AD. Blood samples will be processed on campus by UF's Florida Alzheimer's Disease Research Center Biomarker Core. Blood will be centrifuged and placed into -80°C storage maintained by the PIs. Coded blood samples will be analyzed in the final year of this project. These biomarker levels will not be shared with participants, as this is not a diagnostic laboratory.
Time frame: Baseline, and post-intervention (3 months)
Blood-based AD pathology [p-tau]
Investigators will assess levels of p-tau \[units\], which is sensitive to AD. Blood samples will be processed on campus by UF's Florida Alzheimer's Disease Research Center Biomarker Core. Blood will be centrifuged and placed into -80°C storage maintained by the PIs. Coded blood samples will be analyzed in the final year of this project. These biomarker levels will not be shared with participants, as this is not a diagnostic laboratory.
Time frame: Baseline, and post-intervention (3 months)
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