Depression Clinic

Major Depressive Disorder

What is major depressive disorder?

People with major depressive disorder experience feelings of sadness or difficulty enjoying things in their life for at least two weeks (and often much longer).

Other symptoms may include:

  • Change in appetite (possibly including weight loss or weight gain)
  • Changes in sleep (disrupted/too little sleep or sleeping too much)
  • Feeling tired all of the time
  • Feeling worthless or guilty
  • Concentration problems
  • Decreased interest in sex
  • Crying or tearfulness
  • Thoughts or actions relating to hurting or killing oneself

Individuals who are depressed may feel like they have to push themselves to do what they need to do to carry on with their lives. Other people who are depressed withdraw and give up important activities (e.g., call in sick to work, stop spending time with friends). Overall, individuals who are clinically depressed experience either significant distress over having their symptoms of depression and/or find that these symptoms interfere with their life in some way.

What is the impact of major depressive disorder?

Low life satisfaction Interpersonal problems with family and friends. Impaired work performance (or inability to work).

How common is major depressive disorder?

Kessler et al. (2003) reported that 25% of individuals between the ages of 18 and 29 years old have already experienced an episode of major depression. Research suggests that as many as 85% of these individuals will go on to have another episode of major depression.