Transcranial infrared laser stimulation (TILS) at 1064 nm, 250 mW/cm2 has been proven safe and effective for increasing neurocognitive functions in young adults in controlled studies using photobiomodulation of the right prefrontal cortex. The objective of this pilot study was to determine whether there is any effect from TILS on neurocognitive function in older adults with subjective memory complaint at risk for cognitive decline (e.g., increased carotid artery intima-media thickness or mild traumatic brain injury). We investigated the cognitive effects of TILS in older adults (ages 49–90, n = 12) using prefrontal cortex measures of attention (psychomotor vigilance task (PVT)) and memory (delayed match to sample (DMS)), carotid artery intima-media thickness (measured by ultrasound), and evaluated the potential neural mechanisms mediating the cognitive effects of TILS using exploratory brain studies of electroencephalography (EEG, n = 6) and functional magnetic resonance imaging (fMRI, n = 6). Cognitive performance, age, and carotid artery intima-media thickness were highly correlated, but all participants improved in all cognitive measures after TILS treatments. Baseline vs. chronic (five weekly sessions, 8 min each) comparisons of mean cognitive scores all showed improvements, significant for PVT reaction time (p < 0.001), PVT lapses (p < 0.001), and DMS correct responses (p < 0.05). The neural studies also showed for the first time that TILS increases resting-state EEG alpha, beta, and gamma power and promotes more efficient prefrontal blood-oxygen-level-dependent (BOLD)-fMRI response. Importantly, no adverse effects were found. These preliminary findings support the use of TILS for larger randomized clinical trials with this non-invasive approach to augment neurocognitive function in older people to combat aging-related and vascular disease-related cognitive decline.
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The authors thank Stephanie Oleson and Alex Birdill, who were instrumental in collecting the fMRI data; Evan Pasha, the carotid ultrasound data; and Revanth Poondla, Angelymar Fuentes, Nadia Abdo, and Veronica Almendarez, the behavioral data. EV was supported by a student research fellowship, and FGL was supported by a faculty research fellowship from the College of Liberals Arts of the University of Texas at Austin. This study was supported in part by grants from the National Institute on Aging (R21 AG055772) and the Darrell K. Royal Research Fund for Alzheimer’s Disease.
This study was supported in part by grants from the National Institute on Aging (R21 AG055772) and the Darrell K. Royal Research Fund for Alzheimer’s Disease.
Conflict of interest
The authors declare that they have no conflict of interest.
Research involving human participants
All procedures were approved by the University of Texas at Austin Institutional Review Board (IRB) and were conducted in accordance with the ethical standards of the 1964 Declaration of Helsinki and its later amendments.
Informed consent was obtained from all individual participants included in the study.
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Vargas, E., Barrett, D.W., Saucedo, C.L. et al. Beneficial neurocognitive effects of transcranial laser in older adults. Lasers Med Sci 32, 1153–1162 (2017). https://doi.org/10.1007/s10103-017-2221-y
- Brain photobiomodulation
- Infrared laser