Your name: Your e-mail address: Your friend's e-mail addresses:

(separate multiple addresses with comma)
Indicates required field
Message (limit 100 characters)
Enter answer below:

(Why the math? It protects against spam)
=
Send
Cancel
Your message has been successfully sent!

Studies have shown that genetic makeup plays a role in the etiology of depression, but no study has indicated that depression is solely based on a person's genes. Family, twin, and adoption studies have indicated that genetic factors are involved in the development of mood disorders (affective disorders). Potential genetic markers (that is, specific traits present on the genes) have been identified on specific chromosomes (Souery et al 1977). Some of these markers are directly linked to neurobiological processes, believed to be related to the occurrence of major depression.

The neurotransmitters involved in these neurobiological processes are chemical substances that transmit or block impulses among the nerve cells (neurons) in the brain (Schwartz 1999). Norepinephrine and serotonin have been the most widely studied neurotransmitters in depression research. These may be thought of as up, or excitatory, neurotransmitters. Studies of the effects of antidepressant medications used to treat depression suggest that depression is characterized by low levels of both serotonin and norepinephrine. Depletion of up neurotransmitters is associated with feeling down and depressed.