Like adult ADHD, adult depression is not a one-size-fits-all illness. Clinical depression is the broad-based definition for any depression severe enough to warrant treatment. Clinical depression is also called unipolar depression, major depression, severe depression, or major depressive disorder. Dysthymia is chronic, low-level depression that just won't lift.

Atypical depression often affects women and is characterized by periods of depression that appear to improve but then get worse. Types of atypical depression include overeating, eating disorders, panic attacks, hypersensitivity, and oversleeping.

Bipolar disorder, or manic depression, is marked by roller-coaster highs and lows. The condition is caused by an imbalance in brain chemicals.

How Depression Affects Women

Major and minor depression affects twice as many women as men, regardless of whether or not they also have adult ADHD. Although women are more likely to seek medical help, they are also more prone to blame themselves for the condition and withdraw from society. Here are some key reasons why depression rates are higher in women than men.

• Women are twice as likely to be depressed because of social factors such as physical and sexual abuse, domestic violence, poverty, and single parenthood.

• Research by the NIMH indicates that women are more vulnerable to “life stresses” that contribute to depression, including sexual discrimination at work, increased workloads, and family responsibilities.

• About 10 percent of new mothers suffer from postpartum depression, a type of depression caused by wildly fluctuating hormones after pregnancy. Half of all new mothers experience this milder form of depression.

• Many women suffer from PMS, which includes mild depression and bloating. Premenstrual dysphoric disorder (PMDD), a more serious condition, affects about 4 percent of women and results in severe irritability and depression for up to two weeks prior to or during menstruation. Studies show that, because of underlying hormonal changes, women with PMDD are more likely to suffer from depression later in life.

• Infertility and miscarriage may contribute to depression in women.

• Taking oral contraceptives has been linked to depression in women.

Menopause is another leading cause of depression in women; the dramatic drop in estrogen before, during, and after menopause is to blame. As levels of estrogen decrease, women may have trouble sleeping, experience sexual problems, have annoying hot flashes, have problems maintaining an ideal weight, and suffer from low self-esteem and body image. Lower levels of estrogen can also weaken bones and cause thinning of the hair and skin.

As if that's not enough, for many women menopause coincides with retirement, divorce, or empty nest syndrome and could trigger feelings of mortality. Societal emphasis on youth and beauty can also make it difficult for women going through menopause to feel attractive, worthwhile, or desirable.

Men and Depression

More than 6 million American men are treated for depression every year, but the condition is still undertreated. Blame it on societal standards, but men typically deny or mask their feelings with alcohol, drugs, or by overworking. Because a man's sense of worth is closely tied to his work, many men experience depression after being laid off or fired, especially if they don't have concrete career goals or aspirations.

Male menopause, or midlife crisis, usually affects men between the ages of 35 and 50. A man suffering from a midlife crisis and depression is often discontented and bored with a life that once felt happy and fulfilling.

Depression in Young Adults

Moodiness and adolescence often go hand-in-hand, making the diagnosis of depression and adult ADHD particularly difficult. Studies indicate that as many as one in five teenagers may be depressed. Unfortunately, depression in teenagers is a serious condition and suicide is the third-leading cause of death for adolescents ages 15 to 19.

Symptoms of teenage depression include agitation, restlessness, anger, rage, indecision, hopelessness, helplessness, feelings of guilt, and an inability to concentrate. Failing grades, withdrawing from friends and family, changes in sleep habits, eating disorders, and suicidal thoughts or actions are other tell-tale signs.

Depression in Senior Citizens

About 6 million Americans are aged 65 and older, and one in three of them suffer from depression. Geriatric depression is particularly common among people who are widowed, living alone, have alcohol or substance abuse problems, live with chronic pain, or have a prior history of depression. Seniors taking a combination of drugs may experience depression as a side effect.

Other factors that may trigger geriatric depression include being diagnosed with a serious illness or a loss of independence, such as losing a driver's license or moving to a nursing home. Symptoms of geriatric depression include insomnia, decreased appetite, social withdrawal, and thoughts of suicide or attempted suicide. Geriatric depression may also lower a person's immunity and make her more susceptible to infection and disease.

Unfortunately, 90 percent of seniors suffering from depression are never diagnosed or treated. Some suffer from dementia or other types of mental conditions that have similar symptoms to depressions. Others don't tell family members they are depressed because they fear it could ultimately lead to placement in a managed care facility.

Treat Depression, Adult ADHD, or Both?

For years, medical science believed depression was a natural by-product of living with the disappointments and setbacks of adult ADHD. If adult ADHD were treated, depression would also be alleviated. With that theory in mind, physicians considered adult ADHD the primary diagnosis and took no additional steps to treat the depression.

But recent studies at Massachusetts General Hospital in Boston established depression and adult ADHD as separate conditions that require separate treatments. Today, some medical experts prefer to get depression under control before treating adult ADHD. In this case, depression becomes the primary disorder and adult ADHD is the secondary condition. Other experts prefer to treat both conditions simultaneously in the belief that both disorders must be managed before either one is under control.

Research shows that medications for depression work equally well for adults with and without ADHD.