Clinical depression is more serious and severe than feeling low or sad for a few days. Feeling sad for a transient period, especially after a life changing event such as a bereavement or job change is something that is experienced by almost everyone at some point in their lives.

However, if a person experiences symptoms of depression for most of the day, nearly every day for more than two weeks, they may be suffering from clinical depression. The affected individual or one of their family members or friends should seek diagnosis and treatment from a doctor or a psychiatrist if the symptoms do not improve, if the depression is affecting the person's job, relationships or social life, or if the person is starting to think about suicide or self-harm.

Diagnosis of depression

There are no specific tests for depression. No blood tests can accurately determine the presence or absence of depression, although they can rule out other conditions that share symptoms with depression such as the low mood caused by hypothyroidism. Diagnosis of clinical depression involves:

• A detailed history of symptoms: The person in asked in detail about any life changing events that may have triggered the depression such as a bereavement, divorce or bankruptcy. Details about whether they have had a history of living alone, a deterioration in social relationships, a loss of interest in daily activities and hobbies, problems in the workplace or at school, or a low or irritable mood are also obtained.

  A depressed person may also complain of vague aches and pains, tiredness, sleep problems, loss of appetite and sex drive or gastrointestinal problems such as constipation.

• Since depression is suspected to run in families, details of any depression experienced by first degree relatives (parents or siblings) are also obtained.
• Routine blood tests are performed to rule out other disorders such as thyroid dysfunction.
• There are several talking tests or scales that can be used to assess the severity of depression.

According to the Diagnostic and Statistical Manual of Mental Disorders, certain criteria need to be fulfilled before a person is diagnosed with clinical depression. The person needs to have experienced five or more of the below symptoms over a two-week period. A key symptom that would typically be among these five is a depressed mood or loss of interest.

1. Depressed mood most of the day, nearly daily
2. Lack of interest in daily activities or hobbies
3. Decrease or increase in appetite leading to weight loss or weight gain
4. Decrease or increase in sleep
5. Slowed down mannerisms and behaviour or restless and agitated behaviour
6. Tiredness
7. Feelings of guilt and worthlessness
8. Difficulty in decision making
9. Suicidal thoughts or attempts