Critter Corner: Is Light Therapy an Effective Treatment for Dementia?

Dear Hayek,

I heard that photo therapy, or light therapy, is a safe, non-invasive, and inexpensive way of boosting cognition for patients with dementia. This seems fascinating to me and I’m wondering if you have heard anything about this? If so, please share any information you have and whether this type of therapy is effective. 

Thanks so much for your help!

Laya Therappe

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Dear Laya,

Behavioral and psychological symptoms of dementia often include agitation, aggression, apathy, psychosis, repetitive questioning, wandering, among other behaviors. In a paper published last week in the journal Brain and Behavior, researchers found evidence that light therapy may reduce some of these dementia symptoms.

What is Light Therapy?

Light Therapy is a form of therapy in which patients are exposed to daylight or artificial light by using a special lamp. It is typically used in the treatment of seasonal affective disorder (SAD), which is a form of seasonal depression that occurs during the winter months and affects mood, energy, and sleep in susceptible individuals.

Researchers are Exploring Light Therapy as a Non-invasive Treatment for Dementia

For the paper described, researchers reviewed 12 previous randomized controlled trials. The 12 studies in the meta-analysis included a total of 766 patients, with 426 who underwent light therapy. The rest served as controls for comparison.

“Our meta-analysis indicates that phototherapy improved cognitive function in patients with dementia but had no significant effect on [behavioral and psychological symptoms of dementia] and sleep,” the authors wrote. “This suggests that phototherapy may be one of the most promising non-pharmacological interventions for improving core symptoms of dementia,” the authors continued.

Benefits of Light Therapy

Researchers found that light therapy was associated with improvement in cognitive function, as measured by the Mini-Mental State Examination. There was also some indication that people who underwent light therapy had less severe agitation than controls, the study showed, but the difference between these groups was not statistically significant. 

Potential Limitations

One of the limitations is that researchers focused on only the highest-quality studies that had been published at the time of their analysis, which involved just a small number of participants in total. In addition, the light therapy interventions varied across the 12 studies. For example, eight of the studies used bright light therapy, while two used LED light, and two used blue or blue-green light. The length of light therapy sessions also ranged from 6 to 120 minutes, and from twice a day to five times per week, and were conducted at different times of the day.

Mariana Figueiro, PhD, is the director of the Light and Health Research Center (LHRC) and professor of population health science and policy at the Icahn School of Medicine at Mount Sinai in New York City. She said the variability in how these kinds of studies are carried out is one of the reasons we haven’t seen stronger results from light therapy for dementia. “To me, this is probably one of the biggest issues with light therapy research,” said Figueiro. “But I think the effect is real,” she added. “I’ve seen studies where this is carefully done and you see the impact. Plus, there’s science behind it, a mechanism behind it.”

Trying Light Therapy at Home

While more research needs to be done to determine which type of light therapy intervention produces the strongest results, there are some general guidelines for how to deliver light effectively. In general, the light reaching the eye should be brighter than what is found in the home. In addition, the light should be delivered in a way that ensures the person receives the light no matter which way they look. 

 “For Alzheimer’s patients, what you really want to have is more of a passive intervention, where you are illuminating the entire space where they spend their time,” said Figueiro. “This could be as simple as having people sit outside in the sunlight, or bringing more natural light into a room. If that isn’t possible, lamps can be placed close to where the person usually spends their time.”

Hope this is helpful,

Hayek