Phototherapy for Cognitive Function in Patients With Dementia: A Systematic Review and Meta-Analysis

Abstract

BackgroundDementia is a major health burden worldwide. As numerous pharmacological trials for dementia have failed, emerging phototherapy studies have evaluated the efficacy of alternative therapies for cognition.ObjectiveThe objective of this study was to evaluate the association between phototherapy and changes in cognitive deficits in patients with dementia.MethodsPubMed, Embase, Web of Science, PsycINFO, CINAHL, and Cochrane Central Register of Controlled Trials were searched from inception to 27 March 2022. Inclusion criteria were controlled clinical trials of phototherapy interventions reporting pre-post changes in global cognitive function and subdomains in patients with dementia. Data were extracted by two independent reviewers and pooled in random-effects models. Subgroup and meta-regression analyses were conducted to investigate the sources of heterogeneity.ResultsOur analyses included 13 studies enrolling a total of 608 participants. Phototherapy showed significant associations with improvements of global cognitive function (standardized mean difference [SMD], 0.63; 95% confidence interval [CI], 0.33–0.94; P < 0.001) and subdomains, especially with respect to attention, executive function, and working memory. Near-infrared (NIR) light-emitting diodes (LEDs) photobiomodulation (SMD, 0.91; 95% CI, 0.46–1.36; P < 0.001) and lasers (SMD, 0.99; 95% CI, 0.56–1.43; P < 0.001) showed more significant associations with improved cognitive functions when compared with normal visible light. In addition, the effect sizes of short-term effects (SMD, 0.63; 95% CI, 0.33–0.94; P < 0.001) were larger than effects assessed in long-term follow-up (SMD, 0.49; 95% CI, -0.24–1.21; P = 0.189).ConclusionIn this meta-analysis, phototherapy interventions were associated with cognitive improvement in patients with dementia. NIR LEDs and lasers had advantages over normal visible light. Domain-specific effects were indicated for attention, executive function, and working memory. Short-term improvement after phototherapy was supported, while evidence for long-term benefits was lacking. Stronger evidence for individualized parameters, such as optimal dosing, is needed in the future.Systematic Review Registration[https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=267596], identifier [CRD42021267596].

Effectiveness of non-pharmacological therapies on cognitive function in patients with dementia—A network meta-analysis of randomized controlled trials

“…Although most of the studies included in this article used red light or NIR at wavelengths from 650 to 1,080 nm for intracranial and intranasal irradiation methods, the treatment regimen for PBM was still largely dependent on patient-physician preference. Our findings were consistent with those reported in a previous systematic review ( Zhu et al, 2022 ) that PBM was effective as a novel therapeutic approach to improve the level of cognitive function in dementia patients. This positive effect of PBM relied on four potential mechanisms ( Hamblin, 2016 ), the basic ones involving photon absorption in the mitochondria (cytochrome c oxidase) ( Hennessy and Hamblin, 2017 ), terminal enzymes in the electron transport chain, triggering downstream molecular and biochemical pathways in the mitochondrial respiratory chain, and exerting therapeutic effects ( Lane, 2006 ; Karu, 2008 ; Hamblin, 2018 ); and adjust regional cerebral blood flow to increase perfusion levels ( Chao, 2019 ; Salehpour et al, 2020 ; Baik et al, 2021 ); and open the light-mediated of calcium channels ( Jung et al, 2019 ; Kim et al, 2020 ) and promote the activation of signaling mediators and transcription factors ( Wu et al, 2022 ).…”

Advances in photobiomodulation for cognitive improvement by near-infrared derived multiple strategies

“…The effectiveness of photobiomodulation is significantly correlated with short-term cognitive improvement, but the long-term benefit of photobiomodulation is limited [ 36 ]. Indeed, a single dose of photobiomodulation was reported to improve short-term cognitive function [ 37 ].…”

Energy Conversion and Transfer in the Luminescence of CeSc3(BO3)4:Cr3+ Phosphor

“…To support the sustainable and healthy development of the huge LED industry, which ranges from substrate epitaxy, LED chip fabrication, and LED package to end-use applications, it is urgent to open up new fields of application [1,2]. For this aspect, the red and near-infrared LEDs show a bright future for applications in infrared photography, imaging, photomedicine, biomedicine, sensors, detectors, photosynthetic agriculture, and as a backlight for testing instruments [3][4][5][6][7].…”