Comorbidity is one of the factors that makes diagnosing MDD difficult; many people with depression may suffer from anxiety, OCD, or eating disorders.

Although MDD may lead to a person not being able to keep a job or maintain relationships, it is not an effect, not a symptom of depression.

While major depressive disorder can develop at any age, the median age at onset is 32.5 years old.

Although all of the responses may be part of a clinical interview, the two most important factors in diagnosis is how severe the symptoms are (intensity) and how long they have lasted (duration). 

Remember, construct validity is about how we operationalize and measure a variable.  Asking people to discuss their level of fatigue by asking them to fill in a questionnaire means that it will be difficult to say that when participant one says that his level of fatigue is an "8" out of 10, that is actually the same as someone else who fills in the questionnaire with the same response.

Although grief is associated with sadness, it is not a symptom of Major Depressive Disorder. Although bereavement-related grief and major depression share some features, they are distinct and distinguishable conditions.  However, an individual may develop depression after the loss of a loved one.  This is why it is important that the other criteria for diagnosis are followed to avoid giving medication, for example, to someone who is just going through the normal grieving process.

Although there is some evidence that depression may have an effect on the hippocampus, this is not part of the diagnostic process.

It is most likely due to the collectivistic nature of Chinese culture that they are less likely to focus on their own emotions when interacting with a psychiatrist than Australians, who have an individualistic culture.

Persistent depressive disorder, also called dysthymia (dis-THIE-me-uh), is a continuous long-term (chronic) form of depression. You may lose interest in normal daily activities, feel hopeless, lack productivity, and have low self-esteem and an overall feeling of inadequacy. These feelings last for years.

Avolition is a decrease in the motivation to initiate and perform self-directed purposeful activities.  The most common form is to pull out of social activities.  The student who cries every morning may be experiencing anxiety; there may be many reasons that an athlete drops off of the football team.  Although this could be an example of avolition, the social friend who has withdrawn from all social activity is the most likely case.  As for a friend who does not enjoy going to parties - if this is not a change in behaviour, it is not a problem.