Everyone feels down occasionally, but when low mood persists and affects general functioning, you may have clinical depression.
Although depression is defined as a mood disorder, it also includes symptoms affecting the body (e.g. low energy, sexual dysfunction) and thinking (difficulty concentrating, indecisiveness). It is an illness like diabetes or heart disease. Sufferers cannot simply “pull themselves together”; they need medical treatment.
Depression is common: 6-10% of people experience a depressive episode in any given year. More women than men are affected (2:1); however, depression in males may be underdiagnosed.
Half of patients have first onset between ages 20-50. Depression can begin in childhood or later life, but is less common and tends to present differently e.g. childhood (2%) – apathy; adolescence (5%) – behavioural problems; elderly (25-50%) – physical complaints.
Depression is more likely in socially isolated people.
Three of the more common forms of depressive illness:
- Major Depressive Disorder (MDD) – depressed mood or loss of interest and pleasure in most activities for at least two weeks. Other symptoms, whichinterfere with normal behaviour and functioning,are also present.
- Dysthymia – many of the symptoms for MDD, but less severe and impairing. They may continue for years, however: dysthymia can therefore have severe long-term consequences and become disabling.
- Bipolar Disorder –characterised by alternating episodes of depression and mania/euphoria. In mixed bipolar disorder, both mood states may co-exist. During manic episodes, judgement is often impaired and can causesocially embarrassing behaviour e.g. sexual indiscretions, excessive spending. Two percent of the population is affected over a lifetime, males and females equally.
Other types of depressive illness include:
- Minor Depressive Disorder (same duration, less severe symptoms than MDD)
- Recurrent Brief Depressive Disorder (same symptoms as MDD, but episodes last less than two weeks)
- Premenstrual Dysphoric Disorder (depressive symptoms in the week before menstruation, for at least one year)
- Post-partum Depression (following childbirth, more severe and longer-lasting than transient "baby blues").
Depressive disorders may also be related to drugs and alcohol (Substance Induced Mood Disorders), or to illnesses (Mood Disorder Due to a General Medical Condition).
Depression affects different people differently, and severity varies. Not everyone experiences all the symptoms of a depressive or manic episode. These different presentations can make it difficult to recognise depressive disorder. A sufferer may not seek medical help because they are unaware they are suffering from depression, and that it is a legitimate, treatable illness.
Most commonly reported symptoms:
- Depressed or low mood
- Increased irritability
- Loss of interest or pleasure in activities previously enjoyed
- Tearfulness or wanting to cry, but possibly being unable to
- Decreased sexual interest or other sexual problems
- Appetite changes; unintentional weight gain or loss
- Difficulty falling asleep, waking frequently at night or unusually early and not being able to return to sleep. Or, increased sleep and wishing to be asleep most of the time.
- Feeling fatigued, lacking energy or motivation
- Slowing or speeding up of physical activity or speech
- Feeling worthless, useless and helpless
- Feeling inappropriately guilty
- Difficulty thinking, concentrating or remembering
- Difficulty making decisions
- Feeling life is not worth living; thoughts of death and/or suicide
- Increasingly socially withdrawn
- Poor grooming/self-neglect
- Multiple physical complaints, e.g. frequent headaches, backaches, constipation
- Menstruation changes
- Anxiety symptoms, including nausea, dizziness, breathlessness, heart palpitations, feeling worried and fearful, trembling, sweating, “pins and needles”, frequent diarrhoea and urination.
Causes
Research has revealed several possible causes. There is often a combination of factors in an individual’s history and environment.
Sometimes a specific trigger is identified, but people may become depressed for no apparent reason: this is more likely with a history of previous depressive episodes.
Biological factors
- Neurotransmitters (brain
chemicals). When neurotransmitter functioning is disturbed, e.g. following
use of recreational drugs such as Ecstasy,depression can occur. Different
neurotransmitter systems may be involved, but the two most frequently implicated
are serotonin and norepinephrine. A third brain chemical, dopamine, likely
also plays a role in mood.
- Hormones.Among
other possible hormonal triggers, increased secretion of cortisol from the
adrenal gland during stress is associated with depression. Hypercortisolaemia
can damage the hippocampus (part of the brain associated with hormonal and
behavioural regulation). Thyroid disorders are also often associated with
mood disorders, and patients with depression should be tested for
hypothyroidism (underactive thyroid).
- Neurophysiology. CT scans
and MRI studies, although inconsistent, have shown differences in the size
of certain brain structuresand alterations in blood flow in the brains of
depressed patients.
- Genetics. Having
a close relative diagnosed with a depressive disorder increases risk.
People with genetic susceptibility are more vulnerable to depression being
triggered by life stressors.
- Drugs. Some recreational
and prescription drugscan cause or exacerbate depression, possibly because
they interfere with neurotransmitter regulation or physical structure of
the brain (e.g. excessive alcohol and sleeping tablets cause brain
shrinkage).
- Illness including strokes, Parkinson’s disease, Cushing's disease and thyroid disease, may raise risk.
Psychosocial factors
Stressful life events (e.g. death in the family, financial worries) more often precede the first episode of mood disorder than subsequent episodes. The initial episodeis thought to cause long-lasting changes in brain biology, which increases vulnerability to subsequent episodes.
A family’s internal style of interacting, family environment (e.g. a broken home) and its coping patterns may increase vulnerability to depression, as may an individual’s underlying personality type (e.g. dependent, obsessive compulsive).
When to see a doctor
If you think you or someone close to you has symptoms of depressive disorder, consult your GP. He/she may suggest lifestyle changes, medication or referral to mental health professional.
Take suicidal thoughts, threats or attempts seriously: seek medical help immediately.
Reviewed by Dr Stefanie van Vuuren, Psychiatrist, MB ChB (Stell), M Med (Psig) (Stell), FC (Psych)SA, for Health24, May 2011