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Child Psychiatrist /Adult Psychiatrist

Light Therapy Shows Promise for Sleep, Psychobehavioral Symptoms in AD

Among patients with Alzheimer disease, light therapy led to significant improvements in sleep quality, depression, and agitation.


Light therapy significantly improved sleep and psychobehavioral outcomes among patients with Alzheimer disease (AD), according to a systematic review and meta-analysis published in PLoS One.


Psychobehavioral Symptoms in AD

The primary treatment for AD is pharmacologic therapy which may alleviate some AD-induced cognitive and memory impairment but are neither curative nor halt disease progression. These medications are associated with side effects including poor appetite, diarrhea, and hallucinations. Increasing attention has been paid to photobiomodulation as a potential nonpharmacologic treatment option, however, no systematic evaluation of the efficacy of light therapy in AD has been performed.


Researchers from Weifang Medical University in China searched publication databases through December 2022 for randomized controlled trials evaluating phototherapy in AD. This analysis had 12 outcomes of interest:


  • Sleep efficiency,

  • Interdaily stability,

  • Interdaily variability,

  • Pittsburgh Sleep Quality Index (PSQI),

  • Relative amplitude,

  • Wake after sleep onset (WASO),

  • Alzheimer’s Disease Assessment Scale-Cognitive subscale (ADAS-cog),

  • Cohen-Mansfield Agitation Inventory (CMAI),

  • Cornell Scale for Depression in Dementia (CSDD),

  • Zarit Caregiver Burden Interview (ZBI),

  • Neuropsychiatric Inventory (NPI), and

  • Mini-Mental State Examination (MMSE).


A total of 15 studies comprising 598 patients with AD were included in this analysis. The studies were published between 2005 and 2022 and were conducted in 7 countries across North America, Europe, and Asia. The studies recruited patients with mild to moderate AD (n=9) or moderate to severe AD (n=6). The interventions involved light therapy (n=11) or light therapy devices (n=4).


Light therapy was associated with significant improvements to:


  • Interdaily stability (mean difference [MD], -0.04; 95% CI, -0.05 to -0.03; I2, 0%; P <.00001),

  • Interdaily variability (MD, -0.07; 95% CI, -0.10 to -0.05; I2, 48%; P <.00001),

  • ADAS-cog scores (MD, -0.46; 95% CI, -0.66 to 0.25; I2, 89%; P <.00001),

  • CMAI scores (MD, -3.97; 95% CI, -5.09 to 2.84; I2, 0%; P <.00001), and

  • CSDD scores (MD, -2.55; 95% CI, -2.98 to -2.12; I2, 0%; P <.00001).


Relative to usual care, light therapy improved sleep efficacy (MD, -2.42; 95% CI, -3.37 to -1.48; I2, 60%; P <.00001) and PSQI scores (MD, -1.73; 95% CI, -2.00 to -1.45; I2, 0%; P <.00001).


Light therapy also reduced caregiver burden according to the ZBI (MD, -3.57; 95% CI, -5.28 to -1.87; I2, 0%; P <.00001) and psychobehavioral symptoms according to the NPI (MD, -3.07; 95% CI, -4.14 to -2.00; I2, 79%; P <.00001).


No significant effect of light therapy was observed for:


  • Relative amplitude (MD, -0.06; 95% CI, -0.14 to 0.01; P =.10),

  • WASO (MD, -20.38; 95% CI, -41.88 to 1.13; P =.06), or

  • MMSE scores (MD, 0.44; 95% CI, -0.71 to 1.59; P =.45).


This analysis was limited by pooling data from patients with different AD severity.

“[L]ight therapy significantly improved sleep and psychobehavioral symptoms in patients with AD. These findings combined with its low side effects suggest the role of light therapy as a promising treatment for AD,” the researchers concluded.


This article originally appeared on Neurology Advisor

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