Photobiomodulation improves the frontal cognitive function of older adults

Agnes S. CHAN, Tsz Lok LEE, Kin Chung Michael YEUNG, Michael R. HAMBLIN

Research output: Contribution to journalArticlespeer-review

53 Citations (Scopus)


Objectives: The frontal lobe hypothesis of age-related cognitive decline suggests that the deterioration of the prefrontal cortical regions that occurs with aging leads to executive function deficits. Photobiomodulation (PBM) is a newly developed, noninvasive technique for enhancing brain function, which has shown promising effects on cognitive function in both animals and humans. This randomized, sham-controlled study sought to examine the effects of PBM on the frontal brain function of older adults. 

Methods/designs: Thirty older adults without a neuropsychiatric history performed cognitive tests of frontal function (ie, the Eriksen flanker and category fluency tests) before and after a single 7.5-minute session of real or sham PBM. The PBM device consisted of three separate light-emitting diode cluster heads (633 and 870 nm), which were applied to both sides of the forehead and posterior midline, and delivered a total energy of 1349 J. 

Results: Significant group (experimental, control) × time (pre-PBM, post-PBM) interactions were found for the flanker and category fluency test scores. Specifically, only the older adults who received real PBM exhibited significant improvements in their action selection, inhibition ability, and mental flexibility after vs before PBM. 

Conclusions: Our findings support that PBM may enhance the frontal brain functions of older adults in a safe and cost-effective manner. Copyright © 2018 John Wiley & Sons, Ltd.

Original languageEnglish
Pages (from-to)369-377
JournalInternational Journal of Geriatric Psychiatry
Issue number2
Early online dateNov 2018
Publication statusPublished - Feb 2019


Chan, A. S., Lee, T. L., Yeung, M. K., & Hamblin, M. R. (2019). Photobiomodulation improves the frontal cognitive function of older adults. International Journal of Geriatric Psychiatry, 34(2), 369-377. doi: 10.1002/gps.5039


  • Category fluency test
  • Eriksen flanker test
  • Executive function
  • Low-level laser light therapy
  • Photobiomodulation
  • Randomized sham-controlled trial


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