It's not uncommon for some to have depression and anxiety. Some get depressed from having long term anxiety. Both are thought to be caused by the same thing, low serotonin. Most antidepressants
are SSRI's (Selective Serotonin Reuptake Inhibitors). The way I have understood it, a cell produces serotonin for other cells to use. If it doesn't get used, then the producing cell takes the serotonin back (reuptakes it). The SSRI's make the producing cell not take it back (inhibits the reuptake). That way, the serotonin stays around and eventually gets used and you feel happy/normal. Antianxiety
drugs are sort of like a tranquilizer or symptom dampener. They suppress your nervous system. There are also SNRI's which affect your serotonin and your norepinephrine (another happy chemical). I also take a beta blocker which blocks adrenaline from affecting certain reactions like sweating and racing heart.
Other things like stress, stimulants (sugar and caffeine), diet, lack of sleep or excercise can all affect your body chemistry which ultimately affects your mood through your brain chemistry.
Post Edited (BB1980) : 4/20/2013 12:24:51 PM (GMT-6)