Fear and anxiety are part of life. You may feel anxious before you take a test or walk down a dark street. This kind of anxiety is useful, as it can make you more alert or careful. It usually ends soon after you are out of the situation that caused it.

But for millions of people in the United States, the anxiety does not go away and gets worse over time. You may have chest pains or nightmares and may even be afraid to leave home. If so, you may have an anxiety disorder. Types include panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder (PTSD), and generalized anxiety disorder. Treatment can involve medicines, therapy, or both.

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common mental health disorders affecting children.  ADHD also affects many adults. Symptoms of ADHD include inattention (not able to focus), hyperactivity (lots of movement), and impulsivity (quick acts that occur in the moment without thought).

ADHD is often first identified in school-aged children when it leads to disruption in the classroom or problems with schoolwork.  It can also affect adults. It is more common among boys than girls.

Many ADHD symptoms, such as high activity levels, difficulty remaining still for long periods of time, and limited attention spans, are common to young children in general. The difference in children with ADHD is that their hyperactivity and inattention are noticeably greater than expected for their age and cause distress and/or problems functioning at home, at school, or with friends. For girls, this disorder can manifest primarily as inattention or daydreaming and due to the lack of hyperactivity can be underdiagnosed. Treatment often includes a combination of medication and therapy.

Bipolar disorder is a mental illness that causes “ups and downs” in a person’s mood, energy, and ability to think clearly. People with bipolar disorder experience high and low moods – known as mania and depression – which differ from the typical ups-and-downs experienced by most people.

The causes of bipolar disorder aren’t always clear. It can run in families. Several factors may contribute to the cause of bipolar disorder such as genetics and changes in the brain. Bipolar disorder often starts in a person’s late teen or early adult years, but young children and older adults can have bipolar disorder too. The illness usually lasts a lifetime.

Bipolar disorder is a mental health condition that requires understanding and medical care. If you think you may have it, tell your health care provider. A medical checkup can rule out other illnesses that might cause your mood changes. If not treated, bipolar disorder can lead to damaged relationships, poor job or school performance, and even suicide. However, there are effective treatments to control symptoms such as medicine and talk therapy. A combination usually works best. With proper treatment, individuals with bipolar disorder can live healthy, productive lives.

Depression is more than just feeling down or having a bad day. When a sad mood lasts for a long time and interferes with normal, everyday life, you may be depressed. Depression is a mental health condition that requires understanding and medical care. Symptoms can include sadness, loss of interest or pleasure in activities you used to enjoy, a change in weight, difficulty sleeping or oversleeping, energy loss, trouble concentrating, feelings of worthlessness, and thoughts of death or suicide.

Depression does not have a single cause and sometimes will occur for no apparent reason. Depression is most likely caused by a combination of factors such as genetics, changes in the brain, and environmental factors. Other factors may also contribute to depression such as experiencing a life crisis or traumatic event or having a history of other medical conditions. Depression does often run in families. Depression usually starts between the ages of 15 and 30 and is much more common in women. Women can also get postpartum depression after the birth of a baby. Some people get seasonal affective disorder in the winter. Depression is also one part of bipolar disorder.

If you are one of the more than 20 million people in the United States who have depression, the feelings do not go away. They persist and interfere with your everyday life. Fortunately, people can and do recover from depression.  There are effective treatments, including medications and talk therapy. Most people do best by using both.

Personality disorders are a group of mental illnesses. They involve long-term patterns of thoughts and behaviors that are unhealthy and inflexible.  The behaviors cause serious problems with relationships and work. People with personality disorders have trouble dealing with everyday stresses and problems. They often have stormy relationships with other people. The cause of personality disorders is unknown, but genes and childhood experiences may play a role.

The symptoms of each personality disorder are different. They can be mild or severe. People with personality disorders may have trouble realizing that they have a problem. To them, their thoughts are normal and they often blame others for their problems. They may try to get help because of their problems with relationships and work. Treatment usually includes talk therapy and sometimes medicine.

Psychotic disorders are severe mental disorders that cause abnormal thinking and perceptions. People with psychoses lose touch with reality. Two of the main symptoms are delusions and hallucinations. Delusions are false beliefs, such as thinking that someone is plotting against you or that the TV is sending you secret messages. Hallucinations are false perceptions, such as hearing, seeing, or feeling something that is not there.

Schizophrenia is one type of psychotic disorder. People with bipolar disorder may also have psychotic symptoms. Other problems that can cause psychosis include alcohol and some drugs, brain tumors, brain infections, and stroke.

Treatment depends on the cause of the psychosis. It might involve drugs to control symptoms and talk therapy. Hospitalization is an option for serious cases where a person might be dangerous to him/herself or others.