Biological Influences With Bipolar Disease

The exact cause of bipolar disorder has not yet been determined. Predominant thinking in the psychiatric and medical research fields is that it is a combination of biological, genetic and environmental factors. The following are the most commonly cited biological influences associated with bipolar disorder.

Triggers

• One theory is that bipolar disorder lies dormant until activated or triggered by some biochemical process, such as the over-secretion of a stress hormone, cortisol, or an excessive influx of calcium into the brain's cells.

Genetics

• A team of researchers from both the University of Glasgow and the University of Edinburgh published genetic evidence in 2005 that a damaged gene, known as phosphodiesterase 4B (PDE4B), may be linked to the onset of certain mental disorders such as bipolar and schizophrenia.

Brain Abnormalities

• Reduced sizes of three key regions in the brain were found to be common among bipolar patients: the frontal cortex (judgment, planning, concentration, inhibition and expression), hippocampus (processing and distributing information), and caudate nucleus (regulating and organizing information).

Circadian Rhythm

• Bipolar disease is thought to be influenced by the body's circadian rhythm, the daily regulation of the body's biochemical, behavioral and physiological processes that include body temperature, heart activity, hormone levels, waking, sleeping and eating.

Family

• The family's biological makeup has a great influence on bipolar disease. Roughly 50 percent of people with bipolar disorder have a relative with the disorder, and an individual with a bipolar parent has a 15 to 25 percent chance of having the same condition.

Considerations

• There is no direct evidence that definitively links bipolar disease to any certain causal factor, biological or otherwise.