Depression is a relatively common and serious condition. It runs through the maternal side of my family and I have watched family members struggle with it for decades. I think of depressive illnesses as disorders of the brain. There is some sense that brain chemicals (neurotransmitters such as serotonin, norepinephrine, and dopamine, for example) are out of balance, but it has been difficult to prove this specifically—no surprise since every brain is different. Magnetic resonance imaging (MRI) has shown that the brains of people with depression look different than those of people without depression; brain areas involved in mood, thinking, sleep, appetite, and behavior appear different, but the brain images cannot reveal the reason depression has occurred. In working with people who were depressed, depression was a risk factor for smoking. Other behaviors such as problems with early onset of drinking or lapses in sobriety, physical inactivity, obesity, and sleep disturbances (to name just a few) were associated with depression, as well. More tomorrow.