Excerpt From This Issue:
Some Highlights from the Seventh Meeting of the Society for Light
Therapy and Biological Rhythms, Frankfurt 1995
by Norman E. Rosenthal, M.D.
As someone who has watched the development of the field of light therapy and biological rhythms over the past 15 years, I found the latest meeting of the society dealing with these subjects, which goes under the awkward acronym SLTBR, to be particularly interesting. There is a growing number of first-rate scientists who are devoting their professional lives to the field, the quality of much of the work is excellent, and a solid sense of community has developed among the group of people dedicated to finding out the biological basis for seasonal affective disorder and the way light therapy works. That's the good news.The bad news, if you can call it bad, is that progress is slow. No major breakthroughs were announced and all realistic researchers have accepted that they must hunker down for the long haul of exploration that lies ahead. In this respect, I am reminded of the status of research on a far more serious condition than SAD, namely AIDS. I ran into an AIDS research colleague of mine in the NIH cafeteria the other day and asked him how his work is going. He replied, "We're shifting our mind-set and realize that we're running a marathon, not a sprint".
I arrived in Frankfurt with my son, a college junior who had gamely agreed to accompany me on the trip. At the airport we were immediately identified as light therapy researchers, by our colleagues, who noted that we were wearing darkwrap-around sunglasses to counteract the effects of jet lag. For those readers who are not aware of this, it is possible to prevent jet lag by manipulating your exposure to light and dark at certain times of day, depending on how many time zones you are flying across.Theidea is to shift your biological rhythms into the day-night cycle of the time zone of your destination as rapidly as possible. Even though I know that this should work theoretically, I am always pleasantly surprised by the fact that it actually does work in practice. Those of you who would like to find out more about how exactly to go about beating jet lag might be interested to consult a book on the topic that I co-authored (How to Beat jet Lag.- A Practical Guide for Air Travelers, Oren, D.A., Reich, W., Rosenthal, N.E. and Wehr, T.A., Holt 1993).
The first afternoon was devoted to poster presentations. I presented the work of Dr Norio Ozaki in our group about looking for genes for SAD.The bottom line is that we haven't found any yet, though it is very exciting that the techniques are now available for hunting down and examining various genes of interest. A swing around the poster room revealed the following interesting items:
* A study showing that using light therapy early in the winter season may prevent the development of SAD. This is a controversial finding and others have shown that starting early may be a good policy, but doesn't prevent the development of depressive symptoms if the light treatment is not continued through the winter.
* A controlled study showing that aerobic exercise in the morning is effective in reversing the depressive symptoms of SAD. I've always believed this to be the case, but this is the first time to my knowledge where it has actually been demonstrated scientifically.
* A brain imaging study showing that responses to light therapy in SAD patients were accompanied by increased blood flow through the brain.
* A comparison of light therapy and a standard antidepressant drug (imipramine) in the treatment of non-seasonal depression. Light therapy turned out to be as effective as imipramine, a surprising finding that certainly warrants further investigation.
The oral presentations started the next day. Dr. Michael Young from Rush-Presbyterian-St. Luke's Medical Center in Chicago described the characteristic pattern of development of the symptoms of SAD, beginning in many people with fatigue, increased appetite and oversleeping.
There were three presentations from the National Institute of Mental Health. Dr. Dan Oren described 24-hour hormonal profiles in the blood of patients with SAD, compared with non-seasonal controls. Patients with SAD show low levels of the hormone prolactin, a finding that has also been observed by others. No-one knows what the significance of this finding is and whether it may contribute to the symptoms of SAD. I presented evidence to suggest that a central control center in the brain, the hypothalamus, is disturbed in patients with SAD.This central control unit is responsible for helping to regulate our interior state in response to the many changes that we encounter in our environment. There is evidence that SAD patients have numerous abnormal hormonal responses and abnormal temperature regulation, which may contribute to their symptoms.
Dr. Thomas Wehr presented data on patterns of melatonin secretion during different seasons. Melatonin is a hormone secreted at night by the pineal gland, a small pea-sized structure at the base of the brain. The duration of secretion of this hormone is responsible for many seasonal patterns of behavior in animals. That made us wonder whether it might also be of some importance in causing the seasonal changes in behavior seen in patients with SAD. Dr. Wehr and colleagues found that in non-seasonal women (but not men), the duration of melatonin secretion at night expands during the winter months. It is not clear yet whether patients with SAD show different patterns of melatonin secretion as compared with their non-seasonal counterparts.
Dr. Anna Wirz-Justice and colleagues presented evidence suggesting that taking melatonin tablets orally in the early evening can shift our daily (circadian) rhythms to an earlier time position. This finding is good news for those who tend to get to sleep too late at night and have a hard time waking up on time in the morning. In the past, we have shown that exposure to bright light in the morning hours may help these people adjust their rhythms to a more convenient schedule. Now there is hope that another type of treatment, namely oral melatonin intake in the evening, might have a similar effect.
Dr. Raymond Lamand colleagues from Vancouver reported on a twin study in which they investigated whether seasonal changes in mood and behavior were hereditary. They found a strong environmental influence on such seasonal changes, though a smaller hereditary influence emerged, especially in men. The results of this study are very different from those of Madden and colleagues, who found a strong hereditary basis for seasonal changes in both men and women in their survey of Australian twins.
Drs. Michael and Jiuan Su Terman presented a sophisticated analysis of the results of their ongoing large-scale study of light therapy in SAD. One of the topics they are exploring is the ongoing controversy as to whether light treatment administered upon awakening in the morning is superior to light treatment administered in the evening, which, in their study was just before bedtime. Contrary to the results of some previous reports, both treatment times were equally effective. Earlier this year, the Termans also reported that exposure to negative ions, which are emitted by machines that look like air purifiers, can be helpful to patients with SAD. People may be exposed to fewer negative ions in winter than in summer, in part because these ions are present to a greater extent outdoors than indoors. Such a lack of negative ions might perhaps contribute to the development of SAD symptoms. I should emphasize, however, that the Terman study needs to be replicated and that at this time, the use of negative ions for SAD should be regarded as experimental.
The choice of Frankfurt for the site of the first European meeting of the society was one that our host, Dr. Wilfried Koehler, a professor at the University of Frankfurt, had lobbied for strongly the previous year. The general consensus was that his arguments for Frankfurt had been justified. Based on the brief glimpse I got of Frankfurt, the town is picturesque, with its quaint central square and its views of the river. The meeting took place in a fine auditorium associated with the University. The short-cut between the hotel and the auditorium led through the botanical gardens,which were in full bloom and quite spectacular. On the second evening of the meeting, a banquet was held in the dinosaur hall of one of the museums and we ate surrounded by our colleagues and the skeletons of huge, long-deceased monsters.An award was given to Dr. Jurgen Aschoff for his lifetime of achievement in the field of biological rhythms. Even as the eminence grise, now in his eighties, stood up to collect his award, the Paleolithic atmosphere reminded one of the brevity of a human lifetime.
Although most people were pleased with the organization of the meeting, I did overhear the CEO of one English light box company complaining that the German light box companies had been given a place of honor in the entrance at the front of the stairs, while the other companies were relegated to the sides. I had to admit, there was some merit to the complaint. Aside from such minor gripes, however, the meeting was declared a success. After Frankfurt, my son and I went on to Scandinavia to see what work is being done on SAD and light therapy in Denmark and Norway. But that's another story for another time.
_______________________________________(c) Norman E. Rosenthal, 1995
Norman E. Rosenthal M.D. is a past president of the Society for Light Therapy and Biological Rhythms and the author of Winter Blues: Seasonal Affective Disorder: What It Is and How to Overcome It (Guilford, 1993).