What is Depression? Causes, Signs and Symptoms, Treatment

What is Depression?

There is often no clear distinction between the low moods we all suffer from at some point in our lives and depression, the state when it becomes an illness which needs treatment. Depression may be mild, moderate or severe.

Mild depression may be difficult to recognize and is quite often missed, but depression is not just a more serious form of sadness or being “off-mood”. When in doubt about the diagnosis, it is helpful to look for the psychological symptoms of depression, such as anhedonia (loss of desire for pleasure).

A more severe form of depression is also known as major depressive disorder (MDD) and may result in  suicide. Depression can result from a medical condition or it may be the cause for certain unexplained medical symptoms.

Causes of Depression

A combination of several factors such as genetic, environmental, biochemical, hormonal and psychological variables may result in depression.

  • Stressful events. This is a major cause of depression. It can include death of a loved one, failing relationships, divorce, illness or job loss. Sometimes the trauma may have occurred much earlier in life, possibly in childhood, and is only manifesting in adulthood.
  • Genetic. Growing up with a depressed parent can result in their children suffering with depression but this may be an environmental consideration rather than genetic. However, there have been cases where twins often show similar patterns of depression even when raised apart.
  • Hormonal factors. Cortisol (stress hormone) and melatonin (a hormone secreted by the pineal gland in the brain) have been implicated in depression. 17beta-estradiol (sex hormone predominantly present in females) seems to help overcome depression in women around the time of menopause.
  • Biochemical factors. Certain brain chemicals or neurotransmitters such as serotonin, norepinephrine and dopamine have been found to be involved in regulating mood.
  • Certain personality traits in people, such as negative thinking, pessimism, low self-esteem or overdependence on others predispose to development of depression.
  • Medical conditions such as cancer, myocardial infarction (heart attack), thyroid disorders, stroke or Parkinson’s disease could lead to depressive states.
  • Long-term use of certain medication such as antihypertensives (blood pressure medicines), prednisolone or sleeping pills.
  • Substance abuse – prescription medication, narcotic drug and alcohol abuse.

Signs and Symptoms of Depression

Mild clinical depression can present with :

  • Low mood.
  • Problems with sleep – sleeping excessively or too little.
  • Poor appetite.
  • Negative feelings/emotions.
  • Feelings of hopelessness.
  • Pessimism.
  • Suicidal thoughts.

Symptoms of Major Depression

Loss of interest or desire for pleasure (anhedonia), along with a low mood states (“feeling down”) in addition to 4 or more of the symptoms below may be indicative of major depression. These symptoms should be present almost every day, for most of the day, for a period of at least 2 weeks for a diagnosis of major depression to made.

  • Suicide plans, attempts or recurrent thoughts of self-harm and death.
  • Unexplained or inappropriate feelings of guilt, self-reproach or worthlessness.
  • Inability to function normally due to sluggish thought process or slow movements (psychomotor retardation) or psychomotor agitation.
  • Impaired concentration which is the reduced ability to concentrate.
  • Impaired appetite – low appetite with weight loss. Less frequently, there may be an increase in appetite.
  • Decreased sleep – usually early morning waking with mood variations during the day, worst in the mornings.
  • Low energy and inexplicable tiredness.

Treatment of Depression

Depression should be treated and managed by a medical professional.


Most patients with depression benefit from psychological treatment, such as cognitive behavioural therapy or interpersonal therapy. In case of mild depression, no other treatment may be necessary.


Long-term treatment with antidepressants and other drugs is usually necessary. Most patients respond well to medication and psychotherapy.

  • Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine or sertraline are commonly used to treat depression.
  • Tricyclic antidepressants such as dosulepin or amitriptyline may also be given. Monoamineoxidase (MAO) inhibitors are less commonly used nowadays.

Antidepressants, together with antipsychotic drugs, may need to be used when delusions or hallucinations are present with depression. Electroconvulsive therapy (ECT) may also be indicated in depression with delusions or hallucinations. In bipolar depression, in addition to the above treatment, lithium or valproate prophylaxis may be helpful.