Bright Lighting May Alleviate Some Symptoms of Dementia

By Todd Neale
AMSTERDAM, 11 june 2008--For older patients who have dementia, bright lighting may help correct circadian rhythms and improve cognitive and physical functioning, researchers found.
Compared with patients in assisted living facilities who were exposed to lower levels of light in the dayroom, those exposed to bright lighting had less cognitive deterioration, fewer depressive symptoms, and a slower decline in functional limitations, Eus Van Someren, Ph.D., of the Netherlands Institute for Neuroscience here, and colleagues reported in the June 11 issue of the Journal of the American Medical Association.
A daily dose of melatonin had mixed effects, they said, improving sleep quality but worsening mood and increasing withdrawn behavior.
Therefore, the researchers said, melatonin's "long-term use by elderly individuals can only be recommended in combination with light to suppress adverse effects on mood."
In older patients with dementia, cognitive decline is frequently accompanied by changes in mood, behavior, sleep, and activities in daily living, which may be influenced by changes in the circadian pacemaker in the brain, the researchers said.
Because circadian rhythms may be subject to the effects of environmental light and melatonin, the researchers evaluated 189 older patients (mean age 85.8; 90% female) living in 12 group care facilities in the Netherlands. Most of the participants (87%) were diagnosed with some form of dementia.
Half of the facilities were assigned to bright lighting (±1000 lux) in the common living room and half to dim, or placebo, lighting (±300 lux) from 9 a.m. to 6 p.m. daily. At each facility, participants were randomized to 2.5 mg of melatonin an hour before bedtime each night or to placebo, creating four study groups:
Bright lights only (49)
Melatonin only (46)
Both bright lights and melatonin (49)
Neither bright lights nor melatonin (45)
The mean duration of the study was 15 months (maximum 3.5 years).
Bright lighting alone was associated with a relative 5% attenuation of cognitive decline, as measured on the Mini-Mental State Examination (P=0.04).
Bright lights also reduced depressive symptoms by a relative 19% (P=0.02), slowed the increase in functional limitations by a relative 53% (P=0.003), and increased total sleep duration by 2% (P=0.04).
Treatment with melatonin alone shortened sleep onset latency by 19% (P=0.02), increased sleep duration by 6% (P=0.004), and lengthened the average duration of uninterrupted periods of sleep by 25% (P=0.02).
However, the hormone was associated with worse scores on the positive scale of a mood assessment (P=0.02) and higher scores on the negative scale (P=0.01), as well as an increase in withdrawn behavior (P=0.02).
All three of these negative effects were diminished when melatonin was combined with exposure to bright lights, the researchers said.
The combined treatment also reduced agitated behavior by 9%, increased sleep efficiency by 3.5%, improved nocturnal restlessness by 9%, and reduced the average duration of individual awakenings at night by 12% (P=0.01 for all).
None of the treatments increased the occurrence of adverse events and the bright lights reduced dizziness, headache, inability to sleep, irritability, and constipation, which was also reduced by melatonin.
The researchers hypothesized that the benefits resulted from the synchronization of the circadian timing system, and that light acting on the suprachiasmatic nucleus "may have improved its abilities to synchronize rhythms in, for example, hormones, metabolism, and peripheral oscillators."
In terms of whether the effects were clinically significant, the researchers concluded, "On the whole, light treatment could have clinically beneficial effects."
For instance, they said, the combined effects of melatonin and bright light on sleep, if sustained over time, "could help maintain sleep efficiency above 85%, which has been regarded as a cutoff for clinically relevant disturbed sleep."
Most of the other effects have no accepted cutoff values for clinical relevancy, they said, but the improvements in depressive symptoms could possibly change major depression to minor depression or minor depression to no symptoms.
The authors acknowledged some limitations, including the fact that the trial was conducted in a "somewhat homogenous" population, a high dropout rate, and the fact that the results might not be applicable to men because of the small percentage of them in the study population.
Also, interpretation of the results should be done with caution, they said, because of the multiplicity of analyses and outcomes in the study.
The study was supported by the Netherlands Organization for Health Research, the Netherlands Organization for Scientific Research, the Stichting De Drie Lichten, Stichting RVVZ, Zeist, the Japan Foundation for Aging and Health, Hersenstichting Nederland, and Internationale Stichting Alzheimer Onderzoek. Philips Lighting BV, Braun, and Cambridge Neurotechnology supplied material at reduced cost.The authors made no financial disclosures.

Primary source: Journal of the American Medical AssociationSource reference:Riemersma-van dek Lek R, et al "Effect of bright light and melatonin on cognitive and noncognitive function in elderly residents of group care facilities: a randomized controlled trial" JAMA 2008; 299: 2642-2655.