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Affective Disorders: Types, Incidence, Causes, Diagnosis, Treatment

Affective Disorders

The most important feature of an affective disorder is an alteration in mood and depression.The most common presentation of symptoms is that of a low mood or depression. Less commonly, the mood swings may be high or elated, as in mania.

Affective Disorders
Affective Disorders

Types Of Affective Disorder


Everyone in the normal course of daily life will experience alterations in mood. Depressed mood in this context does not represent a disorder or illness; in fact, lowered mood as a response to the ups and downs of living is considered normal and termed sadness or unhappiness.


In this case they might be irritability or elevation of mood. Mania is used to describe severe form of psychotic disorders.

Bipolar and unipolar disorders

In bipolar disorder patient develops one or more severe episodes of a mood disorder which includes a manic episode. The development of repeated manic episodes alone is sufficient to be termed a bipolar disorder. The disorder can be further categorized as bipolar I, where full-blown episodes of mania occur, and bipolar II, where depressive episodes are interspersed with less severe hypomanic episodes.

Incidence Rate Of Affective Disorder

The lifetime risk of developing a bipolar I disorder is said to be about 1% (0.3–1.5%). The incidence of bipolar I am generally reported to be the same for both men and women, whereas some studies suggest that bipolar II may be slightly more common in women. Studies from America and Europe, using standard assessment tools, found a lifetime prevalence of between 16% and 17%, with a 6-month prevalence of about 6%. Higher rates are consistently found in women but social, economic and ethnic factors are also likely to be influential. In bipolar disorder, an earlier age of onset is suggested, perhaps in late adolescence, with most people experiencing their first episodes before 30 years of age.

Causes Of Affective Disorders

The main cause behind the affective disorders remain unknown but in case of depression, it is likely that genetic, hormonal, biochemical, environmental and social factors all have some role in determining an individual’s susceptibility to developing the disorder.

Genetic causes

In depression, one of the research they have been findings that a variant of the gene responsible for encoding the serotonin transporter protein could account for early childhood experiences being translated into an increased risk of depression through stress sensitivity in adulthood. In bipolar disorder, some genetic linkage has been proposed, but a precise marker remains elusive.

Environmental factors

Although environmental stresses can often be identified prior to an episode of mania or depression, a causal relationship between a major event in someone’s life and the development of an affective disorder has not been firmly established. It may be that life events described as ‘threatening’ are more likely to be associated with depression.

Biochemical factors

In its simplistic form, the biochemical theory of depression postulates a deficiency of neurotransmitter amines in certain areas of the brain. This theory has been developed to suggest that receptor sensitivity changes may be important. Alternative propositions suggest a central role of acetylcholine arising from dysregulation of the cholinergic and noradrenergic neurotransmitter systems.

Endocrine factors

The endocrine system, particularly the HPA axis, and the HPT axis are felt to be implicated in the development of affective disorders. Some endocrine disorders such as hypothyroidism and Cushing’s syndrome have also been associated with changes in mood. People with depression have been found to have increased cortisol levels, which also supported the proposition that mood disorders may be linked to dysfunction within the HPA axis.

Physical illness and side effects of medication

Mood disorders which include depression, have been associated with several types of medication and a number of physical illnesses. Depression can affect the outcome in people with a range of physical problems. An increase in death rates has been found in those patients with co-morbid depression.


There are no proper tests which will confirm the presence of an affective disorder. Various rating scales have been developed that may help to demonstrate the severity of the depressive disorder or distinguish a predominantly anxious patient from a depressed patient.

Rating scales

They are various rating scales used for the assessment of the severity of the disorder. Most commonly used rating scales are the Beck Depression Inventory and the Hamilton Depression Rating Scale.

Rating scales
Rating scales


The aim of treatment is to prevent harm and to relieve distress or to be prophylactic. It is important to differentiate symptoms of the disorder from the premorbid personality. In general, the drugs which are used to control the symptoms of mania are not specifically antimanic. These agents are also used to treat other disorders. This means the diagnosis will primarily influence the way in which these drugs are used rather than the choice of drug per se. Clinicians should be aware of the licensed indication of treatments so that any ‘off label’ use is done knowingly and in line with current best practice.

Treatment of depression

In moderate and severe depression, pharmacological intervention is important, but this should never be considered in isolation from the social, cultural and environmental influences on the patient. Non-pharmacological therapies are effective and in the mild depression, they are considered preferable to drug treatment. Non-drug treatments and antidepressant medication are not mutually exclusive and in some cases, it is preferable to use both in combination.

Treatment of mania

Valproate semisodium (valproate) is licensed in the UK as a specific treatment for mania associated with bipolar disorder. Other antipsychotics, including lithium and benzodiazepines, may also have a role in the management of mania. There appears to be insufficient evidence to differentiate between the various antipsychotics licensed for use in the acute management of mania and as a consequence, the side effect profile, tolerability, previous experience and patient preference should all be considered when selecting the agent to use. Short-term adjunctive treatment with a benzodiazepine may be also be required.

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