Skip to content My WebMD Sign In, Sign Up  If you're depressed,
it might not be easy to figure out why. In most cases,
depression doesn't have a single cause. Instead, it results from
a mix of things -- your genes, events in your past, your current
circumstances, and other risk factors.  Here are a few of the
things that can play a role in depression.    • Biology. We
still don't know exactly what happens in the brain when people
become depressed. But studies show that certain parts of the
brain don't seem to be working normally. Depression might also
be affected by changes in the levels of certain chemicals in the
brain, called neurotransmitters.   • Genetics. Researchers know
that if depression runs in your family, you have a higher chance
of becoming depressed.   • Gender. Studies show that women are
about twice as likely as men to become depressed. No one's sure
why. The hormonal changes that women go through at different
times of their lives may be a factor.   • Age. People who are
elderly are at higher