Bright Light May Not Be Effective Against Depression in Parkinson`s

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - In people with Parkinson disease (PD), bright-light therapy (BLT) is no better at alleviating major depression (MDD) than is a low-light condition, new research from the Netherlands suggests.

"This study provides Class I evidence that BLT is not superior to a control light device in reducing depressive symptoms in patients with PD with MDD," the authors write in Neurology, online February 15.

"Based on our findings, we cannot recommend BLT as a treatment for depression in PD," lead author Dr. Sonja Rutten of Amsterdam UMC told Reuters Health by email.

In the double-blind trial, Dr. Rutten and her colleagues enrolled 83 participants with idiopathic PD and MDD over a five-year period. The researchers randomized them to at-home treatment with either a 10,000-lux daylight-spectrum BLT light box or a 200-lux control light box.

Participants sat near the light source for 30 minutes each morning and evening for three months, followed by a six-month naturalistic follow-up. After several participants withdrew during week 1 of the study, the modified intent-to-treat cohort included 72 participants.

At baseline the participants averaged 64 years of age and 58% were in Hoehn & Yahr PD stage 2. The mean Hamilton Depression Rating Scale (HDRS) score was 14.6, indicating moderately severe depression in most patients.

For the first seven days, participants kept a sleep diary and wore an actigraphy watch and light sensor, and they collected their saliva samples at several time points throughout the study to measure cortisol and melatonin levels.

At the end of treatment, HDRS scores decreased in both groups, with no significant difference between the BLT group (HDRS score, 7.6) and the control group (HDRS score, 8.3; P=0.99). After the follow-up, the mean HDRS score was lower in the control group (5.9 vs. 8.5, P=0.02).

Sleep quality improved in both groups during the trial. There was a slightly greater improvement in the BLT group in subjective sleep rating (P=0.04). Total salivary cortisol secretion declined in the BLT group but rose among the controls (P=0.04).

"We were a bit surprised by our findings," Dr. Rutten said. "Based on the available scientific evidence, we expected BLT to be more effective in reducing depressive symptoms than a control condition. However, we were pleased to see that there was a reduction of depressive symptoms in both the BLT and control group."

"The prevalence of MDD in people with PD is 17%," she noted. "Depression is associated with faster cognitive decline, more severe motor symptoms, a lower quality of life, and higher mortality rates."

"The prevalence of insomnia with PD is at least 30%," she added. "Although more research is necessary to support this hypothesis, we think that structuring the sleep-wake cycle by scheduling light-therapy sessions might be responsible for the antidepressant effects we saw."

"We recommend this treatment for patients in daily clinical practice who have PD and insomnia," she said.

Dr. Rutten explained that antidepressants may have side effects and psychotherapy may not be feasible if they have cognitive impairment, so patients with PD and depression need new treatment options.

Dr. Claire Henchcliffe, an associate professor of neuroscience at Weill Cornell Medical College in New York City, told Reuters Health by email, "The research team had two very interesting findings. First, there was a robust lifting of depression regardless of whether bright light or subdued light was used. So although they could not prove that bright-light therapy is the right treatment, something in the clinical trial helped the patients. One possibility, although highly speculative, is that in addition to any potential placebo effect, imposing a regular sleep-wake schedule in order to give the light therapy might have played a role."

"Second, sleep improved in both bright- and low-intensity treatment groups, and patients reported that their subjective sleep quality was better with bright light than subdued light treatment," added Dr. Henchcliffe, who was not involved in the study. "Intriguingly, the 'stress hormone' cortisol decreased only in the group of patients treated with bright light."

"Light therapy likely has multiple inter-related effects on the brain, and if properly harnessed it could be a safe and tolerable treatment for various symptoms of Parkinson's disease as well as other conditions," she advised. "For now though, we need more understanding of how best to provide the therapy, on what schedule, and for precisely which symptoms, before we can make firm recommendations for patients."

Dr. Rutten and two of her co-authors have financial relationships with Photopharmics Inc, which is developing phototherapy for PD.

SOURCE: https://bit.ly/2TGrri2

Neurology 2019.

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