Changes in mood and cognition are common in older adulthood. Some studies have suggested that transcranial application of near-infrared (NIR) light may have enhancing effects on cognitive and mood status in young adults and individuals with traumatic brain injury. This effect has not been examined in older adults. This study will involve a randomized sham-controlled trial to learn whether NIR stimulation improves cognition and mood in older adults, relative to sham treated controls.

Aim 4 of this study (Parkinson Specific) is registered separately under NCT06688357

There is a dearth of clinically meaningful treatment options at this point in time for individuals who are at increased risk for transitioning to dementia, particularly those with the amnestic variant of mild cognitive impairment (aMCI). While waiting for causative cures and preventive approaches, investigators are faced with the task of identifying modifying therapies that might alter the course or slow down the transition from normal cognition to MCI to dementia.

The proposed study hopes to contribute to this mission by testing the viability of a different type of intervention, one involving transcranial delivery of near-infrared (NIR) wavelengths (808-904nm). Near-infrared stimulation is safe, non-invasive and appears to improve mitochondrial function by promoting increased production of intracellular adenosine triphosphate (ATP) and possibly improved blood flow. Perhaps most compelling are recent findings of reduced beta-amyloid and neurofibrillary tangles in transgenic Alzheimer's mouse models after exposure to real vs sham transcranial NIR stimulation. Preliminary human involving traumatic brain injury (TBI), stroke, and young adult populations have also been promising in terms of positive effects of NIR on cognition.

The overall goal of the present study is to learn whether this unconventional NIR stimulation approach has potential for improving cognition in older adults. To do so, investigators will conduct a randomized sham controlled pilot trial. The intervention will involve six sessions, over a 2-week period in which real or sham stimulation is transcranially applied using a delivery system that has been FDA-approved as a nonsignificant risk since 2003. Researchers hope to learn whether NIR stimulation, relative to sham, has positive effects on cognition and mood in older adults.

Inclusion Criteria:

• Age 62 years or above
• Able to provide informed consent and perform cognitive and mood measures on a computer
• Willingness to be randomized to Sham or Real intervention
• Can devote 2 weeks to the intervention, and additional time for pre and post testing
• 8th grade education and ability to read on 8th grade level based on scores on the Wechsler Test of Adult Reading (WTAR) or the Wide Range Achievement Test-IV (WRAT-IV); or a reading test at 14 pt. text
• On stable doses of major medications; Since some older adults with memory complaints may be prescribed acetylcholinererase inhibitors or related medications by their primary care physicians (i.e., donepezil, rivastigmine, galantaominhe, memantime, or other potential memory-enhancing agent(s), we will not exclude them as long as they have been on stable medications for at least two months and plan to continue this medication during study participation.
• Willingness to allow a study partner (spouse, family member, friend) to answer questions about their cognitive, mood, and other behaviors

Exclusion criteria

• Sensory loss (vision, hearing) or motor deficits that would preclude participation in the experimental cognitive tasks or neuropsychological assessment
• Unstable and uncontrolled medical conditions (metabolic encephalopathy, HIV, moderate to severe kidney or liver disease)
• Previous major strokes or other known significant brain abnormalities or diseases affecting cognition (i.e., multiple sclerosis, seizure disorder, brain surgery, moderate TBI, etc.). No history of brain surgery. Exceptions are a diagnosis of Parkinson's disease for the PD subgroup.
• Evidence of potential dementia (e.g., scores < 24 on the Mini Mental State Exam (MMSE), or < 20 on the Montreal Cognitive Assessement (MoCA), or less than 5th percentile on the Dementia Rating Scale-2 (DRS-2)
• Current or past history of major psychiatric disturbance including schizophrenia, or active psychosis, bipolar disorder, current major depressive episode, current alcohol or substance abuse or history thereof within the past six months. This will be assessed using the Mental Health Screen v.3 (Carroll & McGinley), a modification of the Structured Clinical Interview for DSM-IV psychiatric disorders. We are not excluding individuals who are taking antidepressants or anti-anxiety medications, however, use of antidepressants and anxiolytics will be recorded and data will be analyzed in post-hoc analyses
• Use of antipsychotics, sedatives, or other medications with significant anticholinergic properties (due to potential influence on memory)
• Use of photo-sensitive medications such as steroids or retin-A within 15 days of the study intervention
• Diagnosis of cancer
• Previous participation in a cognitive training study within the last 3 months or current involvement in another study at VITAL or ReVITALIZE, or another study involving cognitive training or intervention at the time of participation

3 participants from the Sham Group opted not to undergo the intervention after passing screeing due to time demands and family health reasons.

3 weeks; collected during intervention and during post-evaluation

Does not differ

This was pilot proof of concept study designed to determine potential effect sizes for a larger study. Small sample size was major limitation. Instead of using overall executive composite score as from the NIH Examiner as major outcome, we recommend breaking down executive function into its components (working memory, fluency) in future studies.