Efficacy of blue light irradiation in improving cognitive function of inpatients with Alzheimer's disease

Abstract

BackgroundAlzheimer's disease （AD） is the most common type of dementia. There has been an increasing trend in incidence rate. The drug therapy has been proven ineffective in improving the cognitive function of AD patients or delaying the disease progression， leading to perceived low adherence with treatment and low efficacy. Previous basic research shows that blue light irradiation is helpful to improve the cognitive function of AD model rats， but there is no corresponding clinical study on the improvement effect of blue light irradiation on cognitive function of AD patients.ObjectiveTo explore the efficacy of blue light irradiation in improving the cognitive function of AD patients， so as to provide references for cognitive stabilization or improvement of AD patients.MethodsA sample of 155 patients who were hospitalized in Geriatric Department of Shenzhen Kangning Hospital from June 2019 to December 2023 and met the International Classification of Diseases， tenth edition （ICD-10） diagnostic criteria for AD were retrospectively selected. Among them， 80 cases who received blue light irradiation combined with memantine therapy and conventional psychotherapy were the study group， and 75 cases who only received memantine therapy and conventional psychotherapy were the control group. Blue light irradiation therapy lasted for 4 weeks， 5 times per week， with each session lasting for 30 min. Then Mini-Mental State Examination （MMSE） and Activity of Daily Living Scale （ADL） were administered at the baseline and after treatment.ResultsAfter treatment， study group reported an increase in MMSE total score， orientation， immediate recall， attention/calculation， delayed recall and language dimension scores （Z=-6.931， -5.773， -4.123， -3.649， -3.508， -4.733， P<0.05）， and a decrease in ADL total score （Z=-7.020， P<0.05） compared to baseline data. Analysis indicated that study group scored higher on MMSE total scale， orientation， immediate recall and language dimensions （Z=-2.784， -4.621， -2.483， -3.463， P<0.05）， and lower on ADL total score （Z=-3.704， P<0.05） than those of control group after treatment.ConclusionBlue light irradiation for AD patients may improve their cognitive function and activities of daily living. ［Fund by National Key Research and Development Project of the Ministry of Science and Technology （number， 2023YFC3603204）； Youth Research Project of Shenzhen Kangning Hospital （number， KN2023A004）］

Keywords

• alzheimer's disease
• photobiomodulation
• blue light irradiation
• cognitive function