DSM-V Criteria for depression
There are many types of depression, and each is classified as a mood disorder. The dominant feature among all mood disorders is the presence of extreme affect (or emotion); either soaring elation (mania) and/or deep depression.
Some mood disorders are characterised by the presence of only depressive mood states (unipolar depression), whilst others are characterised by the presence of manic mood states at certain points in time, followed by depressive mood states at other points in time (bipolar depression). Manic and depressive mood states are understood to exist at opposite ends of a continuum, with ‘normal’ mood existing in the middle.
The most common form of mood disturbance is depression. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), to be diagnosed with major depressive disorder (MDD), five or more of the following symptoms must be present for the same two-week period (with at least one being a depressed mood or a loss of interest or pleasure) and they must represent a change from previous functioning:
- A depressed mood for most of the day, nearly every day (characterised by sadness, emptiness and hopelessness) which is self-reported or observed by others. In children and adolescents, depressed mood may manifest as irritability.
- A noticeably diminished interest or pleasure in all or almost all activities most of the day, nearly every day (as indicated by self-report or observation).
- Significant weight changes (a change of 5% or more in body weight within a month) which are not accountable to dieting. A decrease or increase in appetite nearly every day.
- Insomnia or hypersomnia (excessive sleepiness/sleeping) nearly every day.
- Psychomotor agitation (movement without purpose) or retardation (diminished movement) nearly every day.
- Loss of energy or fatigue nearly every day.
- Feelings of worthlessness or excessive or inappropriate guilt nearly every day.
- Indecisiveness and a reduced ability to think or concentrate nearly every day.
- Recurrent thoughts about death, recurrent suicidal ideation or a suicide attempt or a specific plan for committing suicide.
Diagnosis is warranted if:
- the symptoms cause clinically significant distress or impairment in social, occupational and other areas of functioning;
- the major depressive episode cannot be attributed to the physiological effects of a substance or another medical condition;
- the major depressive episode cannot be explained better by other disorders; and
- there has never been a manic or hypomanic episode.
Bipolar disorders are distinguished from major depressive disorder by the presence of manic (Bipolar I) or hypomanic (a milder mania experienced in Bipolar II) episodes which occur between periods of depression. A manic episode is defined by the DSM-V as:
A distinct period usually lasting about one week in which an abnormally and persistently elevated or irritable mood is experienced in combination with increased goal-directed activity or energy is present for most of the day every day.
During the period of increased energy and mood disturbance, at least three of the following symptoms are present (and they represent a significant change from usual behaviour):
- inflated self-esteem and grandiosity
- decreased need for sleep
- more talkative than usual or a pressure to continue to talk
- thoughts are racing, a flurry of ideas
- easily distracted
- increase in goal-directed activity and psychomotor agitation (movement without purpose)
- excessive involvement in activities which could cause harm (sexual indiscretions, buying sprees or foolish business transactions)
Diagnosis of a manic episode is warranted if:
- the mood disturbance is severe enough to cause considerable impairment in social or work functioning, or to necessitate hospitalisation to avoid harm to themselves or others, or there are psychotic features; and
- the episode cannot be attributed to the physiological effects of a substance or another medical condition.
Prevalence of depression
Results from the most recent National Comorbidity Survey-Replication (NCS-R) found lifetime prevalence rates of unipolar major depression at nearly 17 percent. Rates of unipolar major depression tend to be much higher for women than for men (usually about 2:1).
Estimates suggest that around 2 to 3 percent of the US population will suffer from either bipolar I or bipolar II. Bipolar disorder occurs equally in males and females and usually begins in adolescence and young adulthood (the average onset being between 18 and 22 years of age).
It is important to note that the symptoms of depression can not only affect an individual’s psychological function, but many aspects of their physiological function too. For example, sleep issues are often reported in depression, commonly manifesting as an inability to sleep, early waking or excessive sleepiness or need for sleep. Psychomotor agitation and retardation may also occur, causing an individual to engage in either non-purposeful movement or to experience a significant reduction in their movement. Additionally, changes in weight (either weight increases or weight loss) and appetite (increase or reduction) are also noted in depression, as are changes in one’s energy levels (typically a decrease to the point of fatigue).
Given that these symptoms are relatively broad, it may be worthwhile speaking with a trusted physician to rule out other physiological conditions which are not related to depression (such as vitamin deficiencies or endocrinological dysfunction to name just two).