Bipolar Disorder

August 1, 2011

Bipolar disorder, also known as manic-depressive disorder, is a type of mood disorder, which occurs in approximately 1% of the population. This rate of occurrence is consistent across groups of diverse ethnicity and culture. In general, bipolar disorder is a long-term illness with an episodic and variable course. Unlike major depressive disorder that is significantly more common in women, the occurrence of bipolar disorder is equally common in men and women. Bipolar disorder is characterized by the presence of mania, or a manic episode, defined as a period of abnormal, persistently elevated, expansive, or irritable mood. An individual need only have one manic episode to fit lifetime diagnostic criteria for bipolar disorder. Additional symptoms that may occur in the context of mania include grandiosity or inappropriately elevated self-esteem, excessive or “pressured” speed, diminished need for sleep, racing thoughts, agitation, distractibility, and involvement in activities that potentially lead to negative consequences such as substance abuse, excessive spending, sexual promiscuity, or other high-risk behaviors. Although individuals with a manic episode frequently lack insight into illness (understanding and awareness of their illness), and will deny acknowledgment of their condition if confronted by it, manic symptoms are associated with severe impairments in functioning. Risk of harm to self or others may occur in the context of impulsive decision-making. Some individuals with mania become psychotic or paranoid, and may require hospitalization for protection of themselves and others.

Individuals with bipolar disorder may also experience depressive episodes characterized by depressed mood, diminished interest in everyday activities, difficulty sleeping, significant weight change, decreased energy, feelings of worthlessness or inappropriate guilt, diminished concentration, and thoughts of death or suicide.

Gender appears to be related to the order and frequency of manic and depressive episodes. In men, the first episode is more likely to be manic, and men may be more likely to experience subsequent manic episodes. Women are more likely to have the first mood episode in the form of depression, and may be more likely to experience depressive episodes compared to men. Additionally, women with bipolar disorder are particularly vulnerable to episode recurrence after childbirth, in the postpartum period. Postpartum psychosis may occur, with some women experiencing their first episode shortly after childbirth.

Mean age of onset of bipolar disorder is 21 years; however, there is frequently a 5to 10-year interval between age of onset of illness and age at first treatment or first hospitalization. Bipolar disorder may occur in children and adolescents as well as may occur for the first time in adults over the age of 60. Bipolar disorder is generally a chronic illness, with multiple occurrences of mood episodes. More than 90% of individuals who have a single manic episode go on to have future episodes. Studies on the course of bipolar illness prior to the common use of treatment for the disorder suggest that an average of 4 episodes will occur over a 10-year period, and individuals with untreated bipolar disorder may have more than 10 episodes of abnormal mood states (highs or lows) during their lifetime. The duration of episodes and duration of between-episode periods frequently stabilize after the fourth or fifth episode.

In many cases, an individual will experience several bouts of depression before the occurrence of a first manic episode. For this reason, a diagnosis of bipolar disorder may be overlooked, particularly in the early phases of illness. It is not uncommon to see individuals who eventually are proven to have bipolar disorder being mistakenly diagnosed with depressive disorder, schizophrenia, or even some types of personality disorders.

Clarifying diagnoses can be sometimes difficult, especially in cases where patients may not be knowledgeable about bipolar disorder and its symptoms. This may lead to a non-reporting/under-reporting of manic symptoms. It is critical that the diagnosing clinician be aware of such issues as individual history of mania or hypomania, family history of mood disorder or family history of manic episodes, substance abuse history, and any history of previous treatment. Consultation with family members or significant others is often extremely important. Bipolar disorder may be differentiated from major depressive disorder by the occurrence of mania/hypomania in bipolar illness. Individuals with schizophrenia primarily experience psychotic symptoms such as hallucinations or delusions in contrast to the primary disorder of mood seen in bipolar illness. Individuals with personality disorder, particularly borderline personality, may exhibit labile (rapidly fluctuating) mood state, impulsivity, and risk-taking behavior, which may mimic a manic state. Close observation of symptoms over a longer time period will assist in differentiating these disorders from bipolar illness.

Approximately 5-15% of individuals with bipolar disorder experience four or more episodes within a 12-month period. This variant of bipolar disorder is classified as rapid-cycling type and is more common in women. Other factors that favor the occurrence of the rapid-cycling variant of bipolar disorder, and which are particularly relevant to women, are borderline hypothyroidism (underactive thyroid functioning) and menopause.

Bipolar disorder has both genetic and biological underpinnings. Bipolar illness tends to run in families, and it is known that the concordance for bipolar illness is higher among monozygotic (identical) compared to dizygotic (fraternal) twin pairs. The specific biological factors that cause bipolar illness have not been clearly identified; however, most theories regarding possible biological origins of bipolar disorder involve dysregulation/dysfunction in neurotransmitter systems including the serotonergic, noradrenergic, dopaminergic, cholinergic, GABAergic, and glutamatergic systems.

In addition to the often-serious effects of acute symptoms of bipolar illness, individuals with bipolar disorder frequently have substantial psychosocial difficulties as a result of the disorder. Multiple aspects of life are frequently affected including marriage relationships, child-rearing, and occupational status. Divorce rates are generally higher among individuals with bipolar illness, approaching two to three times the rates of individuals who do not have bipolar illness. The occupational status of individuals with bipolar illness is twice as likely to be impaired as compared to individuals without bipolar illness.

Suicide is also a significant risk in bipolar disorder, with up to 19% of individuals with bipolar illness eventually committing suicide. The risk of suicide appears to be greatest when individuals have depressive symptoms and during the first few years after the onset of bipolar illness. Individuals with comorbid alcohol abuse are more likely to make suicide attempts compared to individuals with bipolar disorder who do not abuse alcohol. Additionally, stressful life events may precede suicide or suicide attempts among individuals with bipolar illness. On the positive side, treatment for bipolar illness, specifically the use of lithium carbonate, has been associated with a sixfold reduction in the rate of suicide attempts among individuals with bipolar illness.

Psychiatric comorbidity is defined as the presence of other psychiatric syndromes in addition to the principal psychiatric diagnosis. In the case of bipolar disorder, psychiatric comorbidity is relatively common, with estimates in the order of 35-65%. The rate of comorbidity between bipolar disorder and substance-related disorder is particularly high, and among all Axis I psychiatric conditions, bipolar disorder appears to have the highest prevalence of comorbid substance abuse. Prevalence rates of substance abuse in bipolar populations have been reported to range from 21 to 58%. Among individuals with bipolar illness, early age of onset is a risk factor for comorbid substance abuse. Although substance abuse is generally seen more often among men than among women, some researchers have reported that among individuals with newly treated bipolar illness, women are more likely to have a history of comorbid substance abuse or dependence compared to men with bipolar illness. However, the issue of substance abuse as it relates to gender in bipolar illness needs further study before definitive conclusions can be drawn regarding gender differences on this specific aspect of bipolar disorder.

SEE ALSO: Depression, Mood disorders, Schizophrenia

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Category: B, Bipolar Disorders