Bright-Light Therapy in Dementia

Désirée A. Lie, MD, MSEd

Disclosures

July 21, 2015

In This Article

Case Presentation

Mrs Sloan is a widowed 83-year-old woman with early dementia. She lives at home with her daughter Diane, who works as a part-time teacher and employs a caregiver for her mother for 5-10 hours weekly. Mrs Sloan dresses and feeds herself, and she enjoys reading, television, and radio. She spends most weekdays at a senior center and enjoys the socializing, music, and activities with other seniors. She rarely goes outside except to get in and out of the car.

Diane recently noticed a poor sleep pattern in her mother, with night awakenings, nocturnal restlessness, and greater daytime agitation that adversely affect Mrs Sloan's mood, functioning, and memory. Diane is increasingly fatigued from checking in on her mother throughout the night. Mrs Sloan is reluctant to begin anticholinesterase treatment.

The patient's metabolic panel (including thyroid function) is normal. The primary care physician has determined that Mrs Sloan is not clinically depressed. He suggests sleep hygiene measures, including more daytime physical activity, avoidance of caffeine after noon, and avoidance of exposure to television just before bedtime. Diane has read about bright-light treatment for persons with depression and dementia and asks whether she should invest in a special lamp or goggles for her mother.

Sleep and Neurodegenerative Disorders

Changes in the brain's circadian pacemaker, located in the suprachiasmatic nucleus, may be stimulated by environmental light and melatonin. In older patients, synchronization of the circadian rhythm may be attenuated owing to reduced melatonin production or light exposure.[1] This attenuation has been noted particularly among patients with Alzheimer disease (AD), Parkinson disease, and Huntington disease.[2]

Sleep has been called the "third pillar" of health (along with diet and exercise),[3] and a recent study suggests that sleep plays a role in preventing the onset and progression of neurodegenerative conditions.[4] In AD, animal and human studies suggest that the sleep/wake cycle affects both the onset and progression of disease, with inadequate sleep possibly being associated with the accumulation of the amyloid-beta peptide.[5] A 2009 Cochrane systematic review[6] found only nine trials that met inclusion criteria and concluded that the evidence was insufficient to assess the value of light therapy in dementia. However, since then, newer studies have emerged to add to the knowledge base.

AD is the most common mental disorder among elderly persons. Approximately 5.1 million adults were affected in 2010, and the numbers are expected to double by 2050.[7,8] It has been suggested that enhancement of the function of the circadian system in older patients with dementia can restore or reduce the decline in cognitive function, sleep, and mood.

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