Bipolar Disorder Symptoms May Follow Seasonal Trajectory
The manic symptoms of bipolar disorder include feeling upbeat and cheerful, being outgoing and energetic, irritability, distractibility, rapid thoughts and speech, grandiose imaginings and high-risk behaviors. Depressive symptoms include feeling sad and blue, being hopeless, disinterest, sluggishness, indecision and thoughts of suicide. Some people experience mixed episodes with symptoms of both mania and depression at the same time.
Generally speaking, people with bipolar I will have episodes of mania or mixed episodes that last at least one week. In some cases, the symptoms of mania may be so severe as to require hospitalization. Depressive episodes last around two weeks. With bipolar II, the episodes are similar though less intense and without the full-blown symptoms of mania.
According to a 10 year-long study conducted at the Roy J. and Lucille A. Carver College of Medicine, bipolar mood swings tend to land toward depression much more often during the dark months of winter. For patients with bipolar II, manic symptoms seemed to appear most frequently right around the autumnal equinox.
The researchers tracked 112 patients with bipolar I and 202 patients with bipolar II. The two types of bipolar are similar, except that those with bipolar II do not experience the full-blown mania symptoms associated with type I. But both forms of the illness revealed certain high-risk time frames.
Among the 112 patients with bipolar I, an average of 10.7 percent of the weeks per month showed mania symptoms. Those symptoms also peaked in August and September. Among the 202 bipolar II patients, 1.6 percent of the weeks showed definitive signs of hypomania. Manic symptoms were greatest in the months of August (2.2 percent) and September (2.4 percent).
Depressive symptoms also followed somewhat predictable patterns. Depression among bipolar I patients seemed to ebb 40 percent of the weeks in July and August. For bipolar II patients the least depressed months were July and October (30 percent).
The low mood seemed to hit hardest in the cold of winter. The trend was true for both bipolar I patients (42 percent of weeks in December and January) and bipolar II patients (32 percent of weeks in January and February).
After initial episodes, relapses also seemed to follow predictable time frames. Bipolar I patients often experienced manic relapses in March, July and October, and depressive relapses in May or August. Bipolar II patients suffered depressive relapses in October and November and hypomanic relapses tended to occur in August.
Researchers say that these seasonal mood shifts could be linked to hibernation, with bright summer months leading to higher energy and dark months promoting sleep and sluggishness.