Bipolar Disorder –Diagnosis and Pathophysiology
Bipolar disorder, also known as manic-depressive disorder, is a psychiatric affective syndrome that is characterized by vacillating changes in mood, energy and activity levels. Some bipolar disorder symptoms are similar to other illnesses, which can make diagnosis difficult. In addition, bipolar disorder is often accompanied by other psychiatric disorders such as anxiety disorder, obsessive disorders, attention deficient disorder, substance abuse, or an eating disorder.
Bipolar disorder is diagnosed based on the symptomatology of behaviors. There are four basic sub classifications in the diagnosis of bipolar disorder. These are defined on the length and intensity of manic and depressive episodes. Less severe manic periods are known as hypomanic episodes. The symptoms for these episodes are the same as normal manic episodes but lack their intensity.
Bipolar I Disorder is delineated by manic episodes that last at least one week. Mania symptoms include insomnia, hyperactivity, lack of impulse control, and distractibility. Psychotic episodes can occur. These episodes frequently require hospitalization to protect the patient and or others. Depressive episodes occur as well and last weeks to months. Depressive manifestations include, inability to perform activities of day living, suicidal ideation, weight gain or loss, and inability to stay concentrated. Episodes of depression with mixed features (having depression and manic symptoms at the same time) are also possible.
Bipolar II Disorder is delineated by a pattern of depressive episodes and hypomanic episodes. There are no full manic episodes.
Bipolar III Disorder or Cyclothymic Disorder is delineated by numerous periods of hypomanic symptoms (NOT episodes) followed by periods of depressive symptoms. These symptoms extend over the course of at least 2 years. This diagnosis is most prevalent in adolescence and may be dismissed by family and healthcare providers.
Bipolar IV and Unspecified Bipolar Disorders are delineated by bipolar disorder symptoms that do not match the other three categories.
For over half a century researchers have attempted to isolate the definitive or suggestive cause of bipolar disorder. Most now agree that there is no single cause. Instead, it is likely that many factors or combination of factors contribute to the illness or increase the risk of developing the disease. Below are some of the suggestive causes:
Genetics
Most research indicates there is a genetic component to bipolar disorder. Children with a parent or sibling who has bipolar disorder are much more likely to develop the illness. Past research studies have pointed to a handful of genes that seem to play a role in bipolar disorder. Research is ongoing to try and isolate/identify the specific genetic component. Though promising, this can only be one factor in the pathophysiology of bipolar disorder since studies of identical twins with identical genetic compositions do not always develop the same disease.
Brain Structure and Chemistry
Brain areas such as the amygdala, basal ganglia, and prefrontal cortex (parts of the limbic system) have all been shown to have physical/structural differences in people with bipolar disorder when compared to those without a mental disorder. The limbic system is responsible for regulations in sleep, appetite, arousal, sexual and endocrine function and emotional states. Alterations in these emotions and behaviors are the hallmark for diagnosis. This disruption is thought to be integral to the pathophysiology of bipolar illness. In addition, people with bipolar disorder also show abnormal myelination in some areas of the brain thought to change affect. Bipolar disorder and other mood disorders seem to be associated with an imbalance in brain chemicals known as neurotransmitters, specifically serotonin, norepinephrine, and dopamine. The cause and impact of these imbalances is not well understood.
A true understanding of the pathophysiology of bipolar disorder is still not fully understood. Inroads must address the neurobiology at molecular, cellular, structural, and behavioral levels to assist these patients with leading a full and productive life.
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