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Biology 202
2001 Third Web Report
On Serendip

Bipolar Disorder

Sabah Quraishi

Bipolar disorder, also known as manic-depressive illness affects about 1.2 percent of the U.S. population (8). It is defined by fluctuating states of depression and mania throughout ones life. Those who are depressed may be restless, irritable, have slowed thinking or speech, decreased sexual activity, changes in appetite and sleep patterns, suicidal thoughts as well as other changes. Those in a manic state may have increased activity or energy, more thoughts and faster thinking, grandiose thoughts, decreased sleep and need for sleep, increased sexual activity, elated mood, irritable mood, as well as other symptoms. Mixed state is when both depression and mania are exhibited at the same time in a cycle. Rapid cycling is when episodes occur more than four times a year. This is more prevalent in women and is also more resistant to treatment. There are two forms of bipolar I disorder, bipolar disorder and bipolar II disorder. The difference between the two is that bipolar I disorder is what is typically thought of as bipolar disorder with episodes of severe mania and depression, bipolar II is when the episodes are depression and hypomania, which is milder than a full manic episode. The exact cause of the disease is unclear. The most probable case is that there are many factors that contribute to the disease.

The diagnosis of bipolar disorder is not exact. Since there is no physiological test for the disease an assessment must be made physiologically. This is done through the administration of behavioral assessment tests, use of scales, basis of symptoms, course of illness and family history. The diagnosis can be tricky especially when it comes to bipolar II disorder. Many with the disease are misdiagnosed with unipolar depression or schizophrenia because hypomania is either unrecognized or severe psychotic mania is misjudged (7).

The onset of bipolar disorder is usually in late adolescence or early adulthood (7). It is possible for both children and adolescents to develop the disease as well. This usually happens when there is a family history for the disease. Children afflicted by bipolar disorder are usually more irritable and destructive during their manic states and are more prone to mixed states (9). It is even harder to diagnose bipolar disorder in children because it is often confused with other problems that occur at a younger age such as attention deficit disorder, conduct disorder, major depression, or schizophrenia (9).

Where and how bipolar disorder is caused is still a bit of a mystery. Some information is known but nothing concrete, and a lot of dead ends. Genetic predisposition is one possible cause for bipolar disorder. The disease usually can be seen throughout a family tree of an affected individual. Twin studies have been conducted to see if there is a higher chance of identical twins, who have the same genetic make up, both getting the disease. These have shown that there is an increased likely hood of one twin to have bipolar disorder if the other has it, but it is not a certainty. The gene for bipolarity has mainly been traced to chromosome 18 as well as some others. It is uncertain which is responsible because it has been found in some cases that chromosome 18 is unaffected in bipolar patients. It is most likely that bipolar disorder is linked to several genes acting together (9). Therefore it seems that genetic predisposition for bipolar disorder is a factor in causing the disease, but it does not make it a certainty.

Chemical imbalances may also contribute to bipolar disorder. The brain has a chemical balance that when disrupted can cause a variety of problems. In looking for cause for depression monoamines, a class of neurotransmitters may play a part. It was found that the drug reserpine, which depletes monoamines, caused severe depression and other drugs that inhibit the breakdown of monoamines elevated moods in patients (10). Monoamine oxidase inhibitors, which block monoamine breakdown, are used as antidepressants. Even more specifically the monoamine norepinephrine is a factor in the cause of depression. In order to regulate the amount of norepinephrine certain drugs are used to block the reuptake of the neurotransmitter blocking it in the synapses. Also, serotonin may affect depression by in turn affecting other parts of the brain through its depletion. The amygdala, involved in emotions, the hypothalamus, involved in appetite, and sleep, and cortical areas, involved in cognition, are all thought to be a part of the cause of depression (10).

There are many influences that can affect the disease. Most importantly stress, which can cause an episode, or help the disease progress (7). The hypothalamic-pituitary-adrenal (HPA) axis is the area of the brain that deals with stress. When the body is exposed to certain stresses the HPA releases corticotropin-releasing factor (CRF), which causes the secretion of the hormones adrenocorticotropic hormone (ACTH), which causes the release of cotisol (10). Cortisol can increase muscle activity, while CRF decreases appetite, sex, and heightens alertness. The continuous activation of this chain of changes can be a cause of depression, and perhaps also mania due to the chemical changes it causes in the brain.

Sleep and the internal clock also affects bipolar disorder. The body's internal rhythm, the circadian clock, is located in the hypothalamus in the suprachaismatic nucleus (SCN), which in addition to other things regulates melatonin. Melatonin is a hormone that is involved in the sleep cycle. Those with bipolar disorders have more difficulty regulating their circadian rhythms, which usually sets itself due to internal and as external conditions (2). The drastic change of rhythms between mania and depression accompanies cycles suggesting a strong link between the two (4). The question is does the abnormality of the circadian rhythm cause the bipolar episode, or does the episode cause the change in rhythm. The former seems to be the more likely because the sensitivity of sleep in patients with bipolar disorder. A change in sleeping habits, such as the loss of sleep or change in sleep schedule can cause a manic episode (7).

There is no cure for bipolar disorder, but there are two forms of treatment, physiological, and psychotherapeutic. Many medications are used and are being found affective in helping this disorder. This may be because the wide ranging causes and symptoms. Different categories of drugs used are mood stabilizers, anti-depressants as well as anticonvulsants. The two most commonly used medications are lithium and valaproate. Lithium, a mood stabilizer, can control episodes and decrease the likelihood of reoccurrence but it is still unknown exactly how it works and why it works for some and not others (7). Valaproate, an anticonvulsant or antiepileptic drug (AED), can also be used as a mood stabilizer and is usually used in cases where the patient cannot stand the side effects of or does not respond to lithium. AED's have been found especially helpful in treating the disease in certain cases such as rapid cycling. These drugs prolong the inactivation of voltage sensitive Na+ channels and affect CHS inhibitory neurotransmitters (3). This suggests some similarity in the biochemical problems of bipolars as well as epileptics. In addition to medication, counseling is important in the control of bipolar disorder. This can include behavioral therapy, family therapy and general education about the disease.

Mental illness, especially bipolar disorder, has been linked to artistic abilities. Many authors, musicians and artists have had the disease, and it is thought that the disease may have enhanced their capabilities. According to some the occurrence of bipolar disorder is 10 to 20 times more prevalent in creative people over the general population (5). There is an argument for and against this hypothesis. From the discussed possible causes of bipolar disorder it seems as though it causing creative ability is doubtful. According to Temple University psychologist Robert Weisberg, mania increases the energy level, but does not give the person ideas they would not have otherwise (12). A manic stage causes faster thinking and action in all bipolars, as does depression cause slower thinking and action. It is unlikely that the quality of creations increases, but rather just the quantity. It is more likely that the stressful, emotional, ever changing lifestyle of an artist contributes to the onset of bipolar disorder.

WWW Sources

1)Our genes, ourselves?

2)What Causes Bipolar Disorders?

3)Developments in the Treatment of Bipolar Disorder

4) Circadian Rhythms Factor in Rapid-Cycling Bipolar Disorder

5) Evening Out the Ups and Downs of Manic-Depressive Illness

6) Bipolar Disorder

7) Bipolar Disorder Research at the National Institute of Mental Health

8) Going to Extremes

9) Bipolar Disorder

10) The Neurobiology of Depression

11) Scientists on trail of manic-depression gene

Other Sources

12) "Portrait of the Artist as a Manic-Depressive". Psychology Today. July/August, 1995

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