Adventures in Bipolar

Bipolar disorder, also known as bipolar affective disorder (and originally called manic-depressive illness), is a mental disorder characterized by periods of elevated mood and periods of depression.[1][2] The elevated mood is significant and is known as mania or hypomania depending on the severity or whether there is psychosis. During mania an individual feels or acts abnormally happy, energetic, or irritable.[1] They often make poorly thought out decisions with little regard to the consequences. The need for sleep is usually reduced.[2] During periods of depression there may be crying, poor eye contact with others, and a negative outlook on life.[1] The risk of suicide among those with the disorder is high at greater than 6% over 20 years, while self harm occurs in 30–40%.[1] Other mental health issues such as anxiety disorder and drug misuse are commonly associated.[1]

The cause is not clearly understood, but both genetic and environmental factors play a role.[1] Many genes of small effect contribute to risk.[1][3] Environmental factors include long term stress and a history of childhood abuse.[1] It is divided into bipolar I disorder if there is at least one manic episode and bipolar II disorder if there are at least one hypomanic episode and one major depressive episode. In those with less severe symptoms of a prolonged duration the condition cyclothymic disorder may be present. If due to drugs or medical problems it is classified separately.[2] Other conditions that may present in a similar manner include drug misuse, personality disorders, attention deficit hyperactivity disorder, and schizophrenia as well as a number of medical conditions.[1]

Treatment commonly includes psychotherapy and medications such as mood stabilizers or antipsychotics. Examples of mood stabilizers that are commonly used include lithium and anticonvulsants. Treatment in hospital against a person's wishes may be required at times as people may be at risk to themselves or others yet refuse treatment. Severe behavioural problems may be managed with short term benzodiazepines or antipsychotics. In periods of mania it is recommended that antidepressants be stopped. If antidepressants are used for periods of depression they should be used with a mood stabilizer. Electroconvulsive therapy may be helpful in those who do not respond to other treatments. If treatments are stopped it is recommended that this be done slowly. Most people have social, financial or work related problem due to the disorder. These difficulties occur a quarter to a third of the time on average. The risk of death from natural causes such as heart disease is twice that of the general population. This is due to poor lifestyle choices and the side effects from medications.[1]

About 3% of people in the United States have bipolar disorder at some point in their life.[4] Lower rates of around 1% are found in other countries. The most common age at which symptoms begin is 25.[1] Rates appear to be similar in males as females.[5] The economic costs of the disorder has been estimated at $45 billion for the United States in 1991.[6] A large proportion of this was related to a higher number of missed work days estimated at 50 per year.[6] People with bipolar disorder often face problems with social stigma.[1]

Genetic
Genetic studies have suggested that many chromosomal regions and candidate genes are related to bipolar disorder susceptibility with each gene exerting a mild to moderate effect.[14] The risk of bipolar disorder is nearly ten-fold higher in first degree-relatives of those affected with bipolar disorder when compared to the general population; similarly, the risk of major depressive disorder is three times higher in relatives of those with bipolar disorder when compared to the general population.[7]

Although the first genetic linkage finding for mania was in 1969,[35] the linkage studies have been inconsistent.[7] The largest and most recent genome-wide association study failed to find any particular locus that exerts a large effect reinforcing the idea that no single gene is responsible for bipolar disorder in most cases.[36]

Findings point strongly to heterogeneity, with different genes being implicated in different families.[37] Robust and replicable genome-wide significant associations showed several common single nucleotide polymorphisms, including variants within the genes CACNA1C, ODZ4, and NCAN.[14][36]

Advanced paternal age has been linked to a somewhat increased chance of bipolar disorder in offspring, consistent with a hypothesis of increased new genetic mutations.[38]

Bipolar spectrum
Bipolar spectrum disorders (BSD) include the following four disorders: bipolar I disorder, bipolar II disorder, cyclothymic disorder, and bipolar disorder not otherwise specified.[64] These disorders typically involve depressive symptoms or episodes that alternate with elevated mood states or with mixed episodes that feature symptoms of both depressive and elevated mood states.[68] The concept of the bipolar spectrum is similar to that of Emil Kraepelin's original concept of manic depressive illness.[69]

Unipolar hypomania without accompanying depression has been noted in the medical literature.[70] There is speculation as to whether this condition may occur with greater frequency in the general, untreated population; successful social function of these potentially high-achieving individuals may lead to being labeled as normal, rather than as individuals with substantial dysregulation.

Evolutionary approaches to depression are attempts by evolutionary psychologists to use the theory of evolution to shed light on the problem of mood disorders. Depression has generally been thought of as dysfunction, but it does not increase with age the way organic dysfunction commonly does. Some researchers have surmised that the disorder may have evolutionary roots, in the same way that others suggest evolutionary contributions to schizophrenia, sickle cell anemia and other disorders. Psychology and psychiatry have not generally embraced evolutionary explanations for behaviors, and the proposed explanations for the evolution of depression remain controversial.