In an 8 week trial conduced in Canada[i], it was discovered that the use of light therapy was effective in the treatment of major depressive disorder (MDD), whether it was used alone, or in conjunction with popular anti-depressant medications, the SSRIs (selective serotonin reuptake inhibitors)
The use of light therapy in treating seasonal affective disorder (SAD) was well established, but the study further proved its utility in treating year round depressive illness.
The study was conducted in three major psychiatric outpatient clinics, and stretch over the course of 5 years, primarily as a result of the difficulty in recruiting suitable patients for the trial.
A total of 122 patients were placed into double blind random groups, and were assigned to either daily exposure to light therapy (immediately upon waking) and a placebo pill, a placebo pill and placebo device, fluoxetine and light treatment, or fluoxetine and a placebo device. Their Montgomery-Asberg Depression Rating Scale (MADRS) readings were taken before and after the completion of the trial.
At the end of the trial, the result obtained demonstrated that:
- The group receiving both light therapy and fluoxetine measured the greatest change in score, with 76% of patients achieving more than a 50% reduction in MADRS number
- In The group exposed to light only, 50% of patients achieved a 50% reduction in MADRS score
- The double placebo group had 33% of patients recording 50% or more reduction in MADRS reading
- Fluoxetine and placebo device group, only 29% of patients achieved a 50% or more reduction in MADRS reading.
Limitations Of The Study
While the results were very promising, the researchers issued the statement that the results must be duplicated, which is probably very likely, before they can positively conclude its efficacy. The reasons for this disclaimer include:
- Sample Size- at just 122 patients, the researchers explained the difficulty in recruiting candidates for the study, and there was likely not enough room to detect statistically significant differences in response
- The Dose Exposure- researchers expressed their desire to conduct further studies using higher doses of both fluoxetine and light, as it was likely to bring out greater changes in response
The researchers concluded that the findings are clear enough to show positive benefit, and for medical practitioners to consider the use of light therapy for major depressive disorder, as it is well tolerated and safe. Finally, they are to conduct studies to determine if the exposure for measurable symptom improvement is the same for both SAD and MDD, or if different treatment protocols need to be designed for each illness.