What are mood disorders? |

Introduction

Descriptions of mood disorders can be found in ancient texts such as the Bible and writings of the ancient Greek physician Hippocrates. Aulus Cornelius Celsus, a medical writer, described melancholia as a depression caused by “black bile” in about 30 CE

Mood disorders are characterized predominantly by a disturbance in mood. Although earlier editions of the American Psychiatric Association’s
Diagnostic and Statistical Manual of Mental Disorders (DSM) grouped a wide variety of disorders under the heading of mood disorders, the fifth edition of the DSM (DSM-5), published in 2013, divides them into two categories: depressive disorders and bipolar and related disorders. Both categories include disorders characterized by mood epidodes, which include major depressive episode, manic episode, and hypomanic episode.

In a major depressive episode, a person experiences depressed mood for a period of at least two weeks. For the diagnosis of a depressive episode, the person must experience at least four of the following symptoms: changes in appetite or weight, sleep, and psychomotor activity; decreased energy; feelings of worthlessness or guilt; difficulty concentrating; or recurrent thoughts of death or suicide. There is significant impairment in occupational or social functioning.

In a manic episode, a person experiences an abnormally elevated or irritable mood for at least one week. In addition, the person must experience at least three of the following symptoms: inflated self-esteem, decreased need for sleep, pressured (loud, rapid) speech, racing thoughts, excessive planning of or participation in multiple activities, distractibility, psychomotor agitation (such as pacing), or excessive participation in activities that may lead to negative consequences (such as overspending). There is severe impairment in social or occupational functioning, or there are psychotic features. The DSM-5 emphasizes that manic episodes typically feature changes in energy level and activity.

A hypomanic episode is characterized by a period of at least four days of abnormally elevated or irritable mood. The affected person must experience at least three of the following symptoms: inflated self-esteem, decreased need for sleep, pressured speech, flight of ideas, increased involvement in goal-directed activities, psychomotor agitation, or excessive participation in activities that may lead to negative consequences. The hypomanic episode is differentiated from the manic episode by less severe impairment in social or occupational functioning and a lack of psychotic features.

The fourth edition of the DSM also described the characteristic of a mixed episode, in which a person displays symptoms of both manic and major depressive episodes nearly every day for a period of one week. However, the American Psychiatric Association determined that such episodes are exceedingly rare and opted to eliminate the category from the DSM-5, replacing it with the "mixed features" specifier, which refers to episodes that are predominantly of one type but have some features of another.

Depressive disorders include major depressive disorder, characterized by one or more major depressive episodes, and persistent depressive disorder, which involves at least two years of depressed mood with symptoms that do not meet the criteria for a major depressive episode. Bipolar and related disorders include bipolar I disorder, which features one or more manic or mixed episodes with major depressive episodes; bipolar II disorder, characterized by one or more major depressive episodes with at least one hypomanic episode; and cyclothymic disorder, represented by at least two years of hypomanic episodes and depressive symptoms that do not meet the criteria for a major depressive episode.

Major Depressive Disorder

Major depressive disorder, often known simply as depression, involves disturbances in mood, concentration, sleep, activity, appetite, and social behavior. A major depressive episode may develop gradually or appear quite suddenly, without any relation to environmental factors. The symptoms of major depressive disorder will vary among individuals, but there are some common symptoms. People with major depressive disorder may have difficulty falling asleep, sleep restlessly or excessively, and wake up without feeling rested. They may experience a decrease or increase in a desire to eat. They may crave certain foods, such as carbohydrates. They may be unable to pay attention to things. Even minor decisions may seem impossible to make. A loss of energy is manifested in slower mental processing, an inability to perform normal daily routines, and slowed reaction time. Sufferers may experience anhedonia, an inability to experience pleasure. They lose interest in activities they used to enjoy. They ruminate about failures and feel guilty and helpless. People with major depressive disorder tend to seek negative feedback about themselves from others. They see no hope for improvement and may be thinking of death and suicide. In adolescents, depression may be manifested in acting out, anger, aggressiveness, delinquency, drug abuse, poor performance in school, or running away. Depression is a primary risk factor in suicide, one of the leading causes of death among young people in the United States.

There is probably no single cause of major depressive disorder, although it is primarily a disorder of the brain. A chemical dysfunction and genetics are thought to be part of the cause. Neural circuits, which regulate mood, thinking, sleep, appetite, and behavior, do not function normally. Neurotransmitters are out of balance. One neurotransmitter implicated in depression is serotonin. It is thought that in major depressive disorder there is a reduced amount of serotonin available in the neural circuits (specifically, in the synapse). This results in reduced or lacking nerve impulse. In many patients with the disorder, the hormonal system that regulates the body’s response to stress is overactive. Stress, alcohol or drug abuse, medication, or outlook on life may trigger depressive episodes.

Cognitive theories of depression state that a negative cognitive style, such as pessimism, represents a diathesis (a predisposition) that, in the presence of stress, triggers negative cognitions such as hopelessness. Negative cognitions increase the person’s vulnerability to depression. Some common precipitants of depression in vulnerable people include marital conflict, academic or work-related difficulty, chronic medical problems, and physical or sexual abuse.

In most cases, medication, psychotherapy, or both are the treatment of choice. Treatment depends on the severity and pattern of the symptoms. With treatment, the majority of people with major depressive disorder return to normal functioning.

Antidepressant drugs
influence the functioning of certain neurotransmitters (serotonin, which regulates mood, and norepinephrine, which regulates the body’s energy). Tricyclic antidepressants act simultaneously to increase both these neurotransmitters. This type of antidepressant has often intolerable side effects, such as sleepiness, nervousness, dizziness, dry mouth, or constipation. Monoamine oxidase inhibitors (MAOIs) increase levels of these same neurotransmitters plus dopamine, which regulates attention and pleasure. MAOIs can cause dizziness and interact negatively with some foods. Selective serotonin reuptake inhibitors (SSRIs) have fewer side effects but can cause nausea, insomnia or sleepiness, agitation, or sexual dysfunction. Aminoketones increase norepinephrine and dopamine, with agitation, insomnia, and anxiety being common side effects. Selective norepinephrine reuptake inhibitors (SNRIs) increase levels of norepinephrine and can cause dry mouth, constipation, increased sweating, and insomnia. The selective serotonin reuptake inhibitor and blockers (SSRIBs) increase serotonin and elicit the fewest side effects (nausea, dizziness, sleepiness). Herbal remedies, such as St. John’s wort, may act like SSRIs. Some drugs blunt the action of a neurotransmitter known as substance P. Other drugs reduce the level and effects of a stress-sensitive brain chemical known as corticotropin-releasing factor (CRF). The hypothalamus, the part of the brain that manages hormone release, increases production of CRF when a threat is detected. The body responds with reduced appetite, decreased sex drive, and heightened alertness. Persistent overactivation of this hormone may lead to depression. The effects of antidepressants are caused by slow-onset adaptive changes in neurons. They may take several weeks to have a noticeable effect.

Psychotherapy works by changing the way the brain functions. Cognitive behavioral therapy helps patients change the negative styles of thinking and behaving associated with depression. Therapies teach patients new skills to help them cope better with life, increase self-esteem, cope with stress, and deal with interpersonal relationships. There is evidence that severe depression responds most favorably with a combination of medication and psychotherapy.

Electroconvulsive therapy (ECT), or shock therapy, is an effective treatment for major depressive disorder. The treatment, first developed in 1934, produces a seizure in the brain by applying electrical stimulation to the brain through electrodes placed on the scalp. ECT reduces the level of CRF. The treatment is usually repeated to obtain a therapeutic response. Common, yet short-lived, side effects include memory loss and other cognitive deficits.

Persistent Depressive Disorder

Persistent depressive disorder comprises the disorders formerly known as chronic major depressive disorder and dysthymic disorder. It is characterized as a mild, chronic depression lasting at least two years. Some people with persistent depressive disorder also develop major depressive disorder, a state called double depression. The disorder is more prevalent in women than in men.

Essentially, dysthymic disorder is a low-grade, chronic depression. Diagnosis of dysthymic disorder requires the impairment of physical and social functioning. Treatment may include cognitive and behavioral therapy as well as pharmacotherapy, especially SSRIs.

Bipolar Disorder

In 1686, Théophile Bonet, a French pathologist, described a mental illness he called maniaco-melancholicus. In 1854, Jules Falret, a French physician, described folie circulaire, distinguished by alternating moods of depression and mania. In 1899, Emil Kraepelin, a German psychologist, described manic-depressive psychosis, later described as bipolar disorder.

There is a genetic link to bipolar disorder, and individuals who have a least one parent with the disorder are significantly more likely to develop it themselves. An increased level of calcium ions is found in the blood of patients with bipolar disorder. There is also a lowered blood flow in the brain, as well as slower overall metabolism. Some research suggests that bipolar disorder may be caused by disturbed circadian rhythms and related to disturbances in melatonin secretion.

The DSM-5 divides bipolar disorder into bipolar I disorder, bipolar II disorder, and cyclothymic disorder. Bipolar I disorder is characterized by the occurrence of one or more manic episodes and one or more major depressive episodes; episodes may also have mixed features. Bipolar II disorder is characterized by the occurrence of one or more major depressive episodes accompanied by at least one hypomanic episode. Cyclothymic disorder is a chronic, fluctuating mood disturbance involving periods of hypomanic episodes and periods of major depressive episodes.

Treatment options include psychotherapy and medication.
Mood stabilizers, such as lithium and divalproex sodium, are the most commonly used medications. Lithium is a naturally occurring substance that increases serotonin levels in the brain. Side effects can include dry mouth, high overdose toxicity, nausea, and tremor. Divalproex sodium increases gamma-aminobutyric acid (GABA) in the brain. Neurotransmitters trigger either “go” signals that allow messages to be passed on to other cells in the brain or “stop” signals that prevent messages from being forwarded. GABA is the most common message-altering neurotransmitter in the brain. Possible side effects of divalproex sodium include constipation, headache, nausea, liver damage, and tremor. Olanzapine increases levels of dopamine and serotonin. Side effects include drowsiness, dry mouth, low blood pressure, rapid heartbeat, and tremor. Anticonvulsants are also widely prescribed. Carbamazepine, for example, increases GABA and serotonin. Possible side effects include blurred vision, dizziness, dry mouth, stomach upset, or sedation. In the case of severe mania, patients may take a tranquilizer or a neuroleptic (antipsychotic drug) in addition to the mood stabilizer. During the depressive episode, the person may take an antidepressant, although some antidepressants are known to intensify symptoms in some patients. ECT may also be helpful during severe depressive episodes.

Specifiers for Mood Disorders

Specifiers allow for a more specific diagnosis, which assists in treatment and prognosis. A peripartum onset specifier can be applied to a diagnosis of major depressive disorder, or bipolar I or II disorder, if the onset is during pregnancy or within four weeks after childbirth. Symptoms include fluctuations in mood and intense (sometimes delusional) preoccupation with infant well-being. Severe ruminations or delusional thoughts about the infant are correlated with increased risk of harm to the infant. The mother may be uninterested in the infant, afraid of being alone with the infant, or may even try to kill the child (infanticide) while experiencing auditory hallucinations instructing her to do so or delusions that the child is possessed. Postpartum mood episodes severely impair functioning, which differentiates them from the “baby blues” that affect many women within ten days after birth.

The seasonal pattern specifier can be applied to bipolar I or II disorder or major depressive disorder. Occurrence of major depressive episodes is correlated with seasonal changes. In the most common variety, depressive episodes occur in the fall or winter and remit in the spring. The less common type is characterized by depressive episodes in the summer. Symptoms include lack of energy, oversleeping, overeating, weight gain, and carbohydrate craving. Light therapy, which uses bright visible-spectrum light, may bring relief to patients with a seasonal pattern to their mood disorder.

The rapid cycler specifier can be applied to bipolar I or II disorder. Cycling is the process of going from depression to mania, or hypomania, and back or vice versa. Cycles can be as short as a few days or as long as months or years. Rapid cycling involves the occurrence of four or more mood episodes during the previous twelve months. In extreme cases, rapid cyclers can change from depression to mania and back or vice versa in as short as a few days without a normal mood period between episodes..

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