Scientists Are Looking for Clues to Depression in Rhythms of Mental Illness
About a third of all clinically depressed patients suffer from manic depression, a revolving door of mood swings that alternate between depression and frenetic activity. Between those extremes usually lie periods of good health and stability. The frequency of cycles varies with each patient, but the average victim of manic depression goes through one manic and one depressive phase in a year.
Sometimes called bipolar illness--as opposed to plain depression, which is “unipolar”--manic depression usually strikes people in adolescence or early adulthood. As it progresses, the cycles repeat themselves with greater and greater frequency, and the moods grow ever more exaggerated.
Since the advent of lithium and other drugs that rein in those moods and help block recurrences, most patients have gone about their lives with fewer or no setbacks. Without treatment, they would be living on a roller coaster.
Rhythms Offer Clues
It is these rhythms in mental illness that intrigue scientists at the National Institute of Mental Health, not only because they may offer clues to causes and treatments of bipolar illness, but because they could help explain other depressions.
Some unipolar depressions have cycles too, says Dr. Frederick Goodwin, director of intramural research at NIMH. About 80% of patients who suffer one bout of depression will have at least one other episode in their lives, he says. Some of these occur with clear predictability, such as seasonal disorders; others may not come at regular intervals.
Several years ago, a study revealed that some depressions are brought on because their victims are not well buffered from the environment. During the cold, dark months of winter, victims tend to slump into depressions and suffer sleeping and eating changes. The treatment is a special light that can be used in winter, mimicking the positive effects of the summer sun.
Further study has revealed another kind of seasonal depression. Some patients, it seems, grow depressed when the thermometer rises above 45 or 50 degrees. While victims of winter depressions used to tell stories of spending money they didn’t have to get to the Caribbean and escape their mental anguish, victims of summer depression talk of diving into ice-cold lakes to find relief, or driving around in Cadillacs whose air conditioners can take the temperature down to 50 degrees or below.
At NIMH, experimental super-refrigerated rooms have been created that relieve these depressions. But more practical solutions are on the horizon.
Recently, researchers started looking at the veins near the eye, which lead to the hypothalamus, where much of the activity involved in depression takes place. Just around the eye, the skin is very thin, leaving the veins underneath easily exposed to temperature changes. It is thought that those veins act as sensors and cooling devices for the brain. The blood is cooled near the eyes, then circulates back to cool the hypothalamus and completes its path back to the eyes. Scientists thought that perhaps cooling that area of the brain would relieve this summer depression.
Informally, some patients have tried using the eye masks that you can buy in a drugstore, putting them in a refrigerator for a few minutes and then resting them on their eyes, which seems to bring relief.
Thomas Wehr, a doctor at NIMH, is working on developing “cool” glasses to alleviate these depressions. They would be run by a battery pack worn in a pocket, and look much like normal glasses with heavy rims.
So far, no formal research has measured the success of these treatments.
Another rhythm that has captured the attention of scientists is the circadian, or 24-hour, cycle. Many symptoms of depression appear as irregularities in the normal flow of daily patterns.
Take sleep: Often depressed patients complain that they sleep all day long but never feel rested. Others toss and turn for hours before they doze off and then sleep fitfully, waking up before they have had a good night’s rest.
One study found that keeping depressed patients up all night brought dramatic improvements in the depression within hours, although the results lasted only about a day. Scientists aren’t sure why that happens, but it could have to do with changes in body temperature during waking hours as well as changes in the balance of certain chemicals.
Out of Sync
About 60% of depressed patients suffer from “phase-advance.” They start their biological day about four hours earlier than normal. For reasons unknown, their bodies don’t seem to be able to read nature’s signals that indicate when the day begins and ends.
Scientists theorize that some of the symptoms of depression may be the result of the patients’ internal clocks being out of sync with nature and that putting the two back in harmony might restore a sense of well-being.
Those internal clocks are linked with body temperature. During the course of a 24-hour period, a healthy person will experience changes in body temperature: In the last third of the night, the temperature begins to rise in anticipation of wakefulness. It continues to rise until mid- to late afternoon, when it starts to fall in preparation for sleep.
In depressed patients, the temperature changes--as well as normal chemical changes in the brain--occur much earlier in the night. The REM sleep, during which dreaming occurs, begins earlier too.
To try to reset these internal clocks, scientists moved up patients’ bedtimes four hours. So instead of going to bed at 10 p.m., let’s say, they would be going to bed at 6 p.m. They were getting a normal amount of sleep; they were just getting it four hours earlier.
Most patients noticed a dramatic recovery. Interestingly, though, even a catnap during the day could throw off the effects. And as soon as the patients returned to a normal bedtime, the depression came back.
So far, the effects of these earlier bedtimes have lasted only about two weeks, at which time the patients’ internal clocks “readjusted.” If at that point they advanced their bedtimes another four hours, their depressions lifted again for another two weeks.
The effects of jet lag, especially after particularly long trips, also last about two weeks. You may feel like you have recovered sooner, but tests show that performance levels don’t return to normal for two weeks. There may be a link between the two phenomena.
