Rhythmic Light Therapy for Alzheimer's Disease Patients

Icahn School of Medicine at Mount Sinai52 enrolled

Overview

The investigator will investigate how light delivering 40 hertz (Hz) affects subjective sleep and cognition in a controlled laboratory study. A lab study will allow the collection of electroencephalogram (EEG) data, perform cognitive tests, and observe the response in those with mild cognitive impairment (MCI) compared to a healthy control group (HC). Participants will attend two study sessions over the course of two weeks. During both sessions, all participants will experience 10 minutes of a low-level light, followed by a data collection period which involves a sleepiness rating, an electroencephalogram (EEG) recording, and a computerized memory test. Participants will then experience either a RL or a placebo RL condition for one hour, after which there will be a second data collection.

The investigator will demonstrate the effect of 40 hertz (Hz) rhythmic light (RL) to promote gamma wave entrainment (rhythmic light \[RL\]) on: brain response (electroencephalography \[EEG\]); cognitive performance (working memory task); and subjective sleepiness (questionnaires). The study will recruit 20 adult mild cognitive impairment (MCI) patients and 20 healthy, age-matched controls (HC) to participate in this study. Sessions will initiate with a 10-minute adaptation period to a low-level ambient light providing illuminance of 15 lux at participants' eye level on a vertical plane, followed by a pre-exposure data collection period, including Karolinska Sleepiness Scale (KSS), EEG, and a working memory task. Participants will experience either 40 Hz RL or placebo RL conditions for a duration of 1 hour, followed by the second data collection period. On the second data collection day, participants will experience the other condition, so that all participants experience both lighting conditions. The experimental sessions will start at 14:00 on each experimental day which will be separated by 1 week.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Interventions

Tailored Rhythmic Lighting InterventionDEVICE

40 hertz (Hz) rhythmic lighting (RL) for a duration of 1 hour. The flicker frequency of the 40 Hz RL will be 40 Hz and the stimulation will be a square wave with a 50 % duty cycle (i.e., 12.5 milliseconds light- on and 12.5 milliseconds light-off). The RL will provide a 30 lux of red light on a vertical plane at the eye level.

Placebo Rhythmic Lighting InterventionDEVICE

Placebo rhythmic light (RL) for a duration of 1 hour. In the placebo RL condition, the duty cycle will be delivered at randomly varying frequencies of 20 Hz and 50 Hz, specifically avoiding the frequency of 40 Hz. The placebo RL conditions will provide a 30 lux of red light on a vertical plane at the eye level.

Eligibility

Sex: ALLMin age: 55 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Participants must be diagnosed with amnestic mild cognitive impairment or mild Alzheimer's disease, as defined by a Montreal Cognitive Assessment (MoCA) score between 17 and 25 * For the age-matched healthy controls, participants must not be diagnosed with mild cognitive impairment or Alzheimer's disease related dementias (MoCA score above 25). * Participants must score a 5 or less in the Pittsburgh Sleep Quality Index (PSQI) Exclusion Criteria: * All participants must not be taking sleeping medication or oral melatonin * Presence of another brain disease that fully explains the dementia (extensive brain vascular disease, Parkinson's disease, dementia with Lewy bodies, traumatic brain injury, or multiple sclerosis) * residence in a skilled nursing facility or long-term care * Major organ failure (e.g., kidney failure) * Uncontrolled generalized disorders such as hypertension or diabetes * Obstructing cataracts, macular degeneration, and blindness * Severe sleep apnea or restless leg syndrome * History of epilepsy

Outcomes

Primary Outcomes

Change in Electroencephalography (EEG) Power at 40 Hertz (Hz)

Electroencephalography (EEG) recordings - the change in 40 Hz gamma power, computed by calculating the difference between the average gamma power at baseline (T1) and during the light intervention (T2). This difference was obtained by subtracting baseline 40 Hz power from the intervention 40 Hz power to assess acute neural effects

Time frame: baseline and during the light intervention

Secondary Outcomes

Mean Change in Subjective Sleepiness Using the Karolinska Sleepiness Scale (KSS)

The Karolinska Sleepiness Scale (KSS) outcome prompts participants to rate how sleepy or alert they are feeling on a scale ranging from 1 to 9, where 1 = "very alert," 3 = "rather alert," 5 = "neither alert nor sleepy," 7 = "sleepy, but no difficulty remaining awake," and 9 = "very sleepy, fighting sleep, an effort to remain awake."

Time frame: Baseline and 1 hour after intervention (intervention is 2 hours)

Cognition Using a Working Memory Task

Participants view a serial visual display of letters and math problems. They are asked to hold the letters in memory while simultaneously determining if the simple math problems are correct (e.g., 7+5=13). Performance is assessed in percent correct and by measuring accuracy and Reaction Time (RT).

Time frame: 1 hour after intervention (intervention is 2 hours)