It is quite normal for a person to feel sad or elated and, though they may affect the way a person behaves, these emotions are part of the normal human experience. However, it is possible to go far beyond the normal range to a point where the emotion is not felt but instead dominates a person's life, preventing them from functioning and even making them a risk to themselves or others. Around 20% of women and 10% of men will suffer from recurrent depression at some stage in their life, and another 1% of the population will develop bipolar affective disorder. Both are most common in early adult life, though a wide range of people of all ages and from all walks of life are affected. This entry looks broadly at the mood disorders and provides links to other, more detailed entries on h2g2.

(The definitions of diseases mentioned in the entry are based upon the criteria listed in the International Classification of Diseases, 10th Revision.)

Low Mood

Depression differs from normal low feelings both through its duration and the effect it has on those suffering from it. A first episode of depression may follow a devastating life event, though it is thought that depression has a genetic component and that those with depression have a shortage of the neurotransmitters whose levels are increased by anti-depressants. The key symptoms seen in depression are a low mood, a lack of pleasure from previously enjoyable pastimes (anhedonia), and a lack of energy (anergia). At least two of these three symptoms must persist for two weeks for a diagnosis of a depressive episode to be made, and at least two of the following symptoms should also be present:

• Reduced concentration and problems maintaining attention.
• Low self-esteem and feelings of low personal worth.
• Ideas of guilt and feelings of unworthiness.
• Hopeless and pessimistic views of their future.
• Thoughts, planning or actions of self-harm or suicide.
• Problems with sleep, such as insomnia or excessive sleeping.
• Changes in appetite, including both loss of appetite and overeating.

The severity of depression can also be determined using these two lists of symptoms. Mild depression is present when a person has four or more symptoms, while moderate depression usually includes at least six. Severe depression is diagnosed when a person suffers from all three key symptoms plus at least four from the second list.

Some cases of depression also include so-called psychomotor symptoms, where the person's manner and movements are altered by the disease. These tend to fall into two classes: retardation and agitation. Psychomotor retardation leads to a slowing of thought and movement, with the person taking a long time to reply to questions and then doing so in a slow, flat voice. The individual may have an expressionless face and may in severe circumstances become mute, unresponsive and virtually motionless – this is known as a depressive stupor. Alternatively, individuals may be affected by psychomotor agitation, making them restless so that they constantly fidget or pace around the room.

Finally, in severe cases, depression can produce psychotic symptoms in keeping with the person's state of mind. They may have hallucinations in which voices accuse them of worthlessness or criticise their actions, or they may hallucinate an awful smell such as that of dead rotting flesh. They may also develop delusions that they are guilty of things they have not done, that they are dead or do not exist, or that their insides are slowly rotting away. Symptoms such as these are more common in psychotic disorders such as schizophrenia, but can still occur in depression, leading to a diagnosis of 'severe depression with psychotic symptoms'.

Diagnoses

A person presenting with the above symptoms for the first time would be diagnosed with a mild, moderate or severe depressive episode. If an individual has a second depressive episode they are diagnosed with recurrent depressive disorder provided they have not had any episodes of mania or hypomania, which would point to a diagnosis of bipolar affective disorder (see below). On the other hand, individuals suffering from a continuous mildly depressed mood rather than episodes of depression may be diagnosed with dysthymia, a long-term condition that rarely becomes severe enough to warrant diagnosis with depression.

As opposed to being the main diagnosis, depression may instead be due to another mental health condition such as anxiety, adjustment disorder, an eating disorder, a personality disorder or a psychotic disorder. It may also present on equal footing with schizophrenia, in which case the complicated diagnosis of schizoaffective disorder is used.

It is particularly important to remember that depression can also arise from diseases outside of the scope of mental health, such as stroke, HIV, cancer and arthritis. A state of depression can also be induced by continually using a psychoactive substance such as alcohol.

A mention should also be made of the entry on Seasonal Affective Disorder (SAD), which deals with a condition that is different from depression but which causes depressive symptoms on a seasonal basis due to lack of daylight.

Prognosis

While a single episode of depression will peter out within six months to a year, more than 60% of individuals will go on to have further episodes. While depression is often very treatable, it is an important risk factor for suicide with depressed individuals being 20 times more likely to commit suicide.

Coping With Low Mood

h2g2 has a range of helpful entries that deal with depression:

• Medication for Depression
• Overcoming Depression
• Teenage Depression
• Depression and College Students
• Depression Survival - a Personal Account

Elated Mood

Unlike depression, the severity of elated mood is not based on the number of symptoms present, but their severity. There are thus three levels: hypomania, mania and mania with psychotic symptoms. While the basic symptoms involved are the same and both have a certain impact on a person's life, hypomania is less severe than mania. The crucial difference is that a person experiencing hypomania can still just about cope with normal activities, whereas if they were to progress to a state of mania they would be completely incapable of normal function. The loss of contact with reality that occurs during mania is not to be understated. Those who develop psychotic symptoms as part of severe mania may even fail to eat, drink and wash properly, making it a thoroughly debilitating experience.

The basic symptoms of hypomania and mania are:

• Feelings of euphoria, irritability or fluctuating mood.
• Sleeping less, but not becoming fatigued.
• Increased energy leading to risk-taking and overactivity.
• Disinhibition, including promiscuity.
• Raised self-esteem or a sense of self-importance.
• Difficulty concentrating on a particular thing.
• Accelerated thinking and fast speech.
• Reduced insight and ability to judge risks.

The psychotic symptoms affecting those with severe mania include:

• Circumstantial speech, which takes a while to get to the point.
• Tangential speech, which heads off on tangents and never gets to the point.
• Flights of ideas, where loosely-linked thoughts rush through the mind.
• Delusions of grandeur or persecution.
• Altered perceptions making sounds louder and colours brighter.

Diagnoses

While a hypomanic episode can be diagnosed after just a few days, symptoms must last for at least a week and interfere completely with normal activities for a manic episode to be diagnosed. It is not uncommon for a mixture of depressive and manic symptoms to be present at the same time, thus leading to a diagnosis of mixed affective episode. These terms are all used for an individual's first episode of disturbed mood – once a second episode occurs then the label of bipolar affective disorder can be applied. Note that it is not necessary to have had both mania and depression to be diagnosed with so-called 'manic depression', though those who have only experienced depressive episodes will fall into the category of recurrent depressive disorder instead. It is also worth noting that thryoid disease may cause and, more rarely, be caused by bipolar affective disorder.

In cases where all the other diagnoses have been excluded, there is another diagnosis that requires consideration. Cyclothymia, a condition that produces numerous episodes of elation and depression, none of which are severe enough to be considered as hypomania or mild depression. Though it is often described as being a mild variant of bipolar disorder, the mood swings caused by cyclothymia are rapid and may be harder to diagnose than those of bipolar disorder. Treatment may be ineffective due to the rapid changes in mood, though the individual may not require any treatment other than relaxation and regular exercise, and may even find the mood swings useful in terms of the creative advantage they bring.

'Manic' symptoms may also be caused by depression – 'agitated depression' can present with irritability, and psychomotor agitation (see above) can be hard to distinguish from mania. Mania may also present on equal footing with schizophrenia, in which case the complicated diagnosis of schizoaffective disorder is used. Finally, it is important to remember that some medical conditions can cause symptoms of mania by interfering with the normal working of the brain, and that a range of psychoactive substances can produce an elated mood.

Prognosis

Unfortunately, around 90% of individuals experiencing a first manic episode will have further episodes, with an average of one every two to three years. Around 10% of those with bipolar affective disorder have more than four episodes of depression or mania per year and have a poor prognosis, being referred to as rapid cycling. Though there is much that can be done to help individuals with bipolar affective disorder, around 10% will eventually commit suicide.

Coping with Elated Mood

For more information about 'manic depression' and how to deal with it, see the entry on Bipolar Disorder.