Mood Disorders
(Affective Disorders)

Mood disorders are millennia old “companions” of humanity. As early as in the 4th Century BC the greek physician Hippocrates described the symptoms of depression and mania, which he regarded as disturbances of the “black and yellow bile”. The concept of melancholy (from the Greek μελας melas, “black” and χολη cholé, “bile”) still bears traces of the system described by Hippocrates, the so called concept of humoral disturbances (“concept of four humors”), in which he suspected a surplus of “black bile” in the body as the cause of melancholy.

Definition according to ICD-10

The International Classification of Diseases (ICD-10) defines mood disorders (affective disorders) as illnesses in which the fundamental disturbance is a change in mood or affect (either to depression or to elation). The mood change is usually accompanied by a change in the overall level of activity. The affective disorders are associated with many other symptoms that are associated with the change of mood and activity. Most mood disorders are prone to relapse. The beginning of each episode is often associated with stressful life events or situations.

The affective disorders include the manic episode, the bipolar affective disorder, the depressive episode, the recurrent depressive disorder, the cyclothymic disorder and the dysthymic disorder.

Definition based on the DSM-5

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) summarizes the disorders depression, mania, cyclothymia and dysthymia as mood disorders.

According to the DSM-5 a major depression is a depressive disorder which persists for at least two weeks.

The DSM-5 distinguishes the bipolar affective disorders in bipolar-I-disorders and bipolar-II-disorders.

The dysthymic disorder is described as a disorder with depressive symptoms over a period of at least two years, but who does not reach the severity of a major depression.

The cyclothymic disorder is described as a disorder with at least two years of depressive and hypomanic phases, which does not reach the severity of a bipolar disorder.

Differential Diagnoses

During the process of differential diagnosis it must be determined, if the disorder is a primary affective disorder, or if the symptoms occur in connection with another physical or mental illness. In addition to the physical illnesses and substance side effects mentioned below, psychiatric disorders, specifically the presence of an anxiety disorder or schizophrenic symptoms should be considered.

Affective Disorders in Organic Diseases

Nearly all physical illnesses have an impact on the mood of the patients (and their families). Many organic diseases can also lead to manifest depressive symptoms. It can be differentiated in depressive symptoms as the result of an adjustment disorder (in approximately 25% of all chronic ill patients!) and on the other hand in depressive symptoms directly associated with the organic disease such as in certain metabolic diseases.

At the onset of an affective disorder, the following diagnostic procedures should be considered:

Further tests such as thyroid function, HIV testing, etc. could be considered according to the symptoms and the case history.

Metabolic Diseases

If necessary, metabolic disorders should be excluded, in particular an underactive or overactive thyroid (hypothyroidism and hyperthyroidism) or an adrenal hypofunction and hyperfunction (Cushing's disease, Addison's disease).

In addition to the above mentioned diseases also the hyperparathyroidism, the hypoparathyroidism and the diabetes mellitus can be associated with depressive symptoms. In some cases it might be necessary, to consider a multiple endocrine neoplasia (MEN).

If patients suffer from recurrent depression in addition to abdominal pain, vomiting, acute neuropathy, etc., a porphyria should be excluded.

Infectious Diseases

In some cases the exclusion of an HIV infection is necessary to rule out an acquired immunodeficiency syndrome (AIDS) with involvement of the central nervous system. Depressive symptoms may be caused by various other infectious diseases such as mononucleosis (glandular fever), viral pneumonia, influenza (flu) or typhoid fever.

Cerebral Diseases

A cerebral hypoperfusion may lead to secondary affective disorders. Possible causes for a reduced perfusion of the brain, such as heart failure or cardiac arrhythmias, should be considered.

Impaired pulmonary ventilation such as in sleep apnea or chronic obstructive pulmonary disease (COPD) may lead to an insufficient supply of oxygen of the brain.

Neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease or encephalomalacia, inflammatory brain diseases such as disseminated encephalomyelitis, or a poorly controlled epilepsy can cause depressive symptoms.


Neoplasia may cause depressive symptoms. In addition to the exclusion of cerebral tumors especially the exclusion of pancreatic cancer and leukemia should be considered.

Mood Disorders due to Drug Side Effects

Various types of medication can cause depressive symptoms as side effects. These include:

Mood Disorders in Alcohol an Drug Use

Daily consumption of alcohol correlates to a large degree with the appearance or presence of depressive symptoms. Therapeutically, the primary focus in these cases is the treatment of alcohol dependence.

Drug use can lead to serious emotional disturbances. Long-time use of cannabis or abuse of amphetamine may cause anxiety, depressive or psychotic symptoms. Long-time cocaine use may cause manic or depressive symptoms.


The point prevalence of all mood disorders combined is about 15-30%, which means about one in four people suffer from more or less marked changes in mood and emotion. Among the more severe affective disorders, the depressive episode is the most common with a point prevalence of approximately 5%.


Affective disorders are often recurrent with cycles of more or less “healthy” episodes and episodes of mood changes. There can also be a seasonal clustering in which the mood changes occur during certain seasons, especially in winter. The term “rapid cycling” refers to the occurrence of at least four episodes of the illness within 12 months.


The various symptoms of the mood disorders are further characterized in the chapters of the respective disorders:

   • Bipolar Affective Disorder
   • Depressive Disorders
   • Cyclothymic Disorder
   • Dysthymic Disorder

Dr. Sandra Elze & Dr. Michael Elze