Mental illness is a collective term that refers to all the different types of mental conditions, including those that affect your mood, your thinking and your behavior. To be classified as a mental illness, a condition must cause distress in your life and reduce your ability to function in one or more areas of your life, such as at work, in relationships or in social situations.

More than 200 conditions are classified as mental illnesses, ranging from minor to severe. Common mental illnesses include depression and schizophrenia.

A mental illness is technically considered a disorder rather than a disease because it's classified by descriptions of signs and symptoms that are open to interpretation. In general, what's considered a mental illness comes down to the severity of signs and symptoms, how long they've lasted, and how much they impair your ability to function in your daily life.

Signs and symptoms of mental illness can vary greatly depending on the particular disorder and your age, among other factors. Symptoms also can be related to emotions, thoughts (cognitive), behavior or physical issues.

Emotional, behavioral and cognitive symptoms
Emotional, behavioral and cognitive symptoms of mental illness may include:

• Feeling sad or down
• Confused thinking
• Excessive fears or worries
• Withdrawal from friends and activities
• Problems sleeping
• Delusions or hallucinations
• Inability to cope with daily problems or stress
• Alcohol or substance abuse
• Significant changes in eating habits
• Sex drive changes
• Excessive anger, hostility or violence

Physical symptoms
Physical symptoms of mental illness may include:

• Numerous unexplained physical problems
• Fatigue
• Back pain
• Chest pain
• Digestive problems
• Dry mouth
• Headache
• Sweating
• Weight gain or loss
• Rapid heart rate
• Dizziness

Putting symptoms into context
When exactly a symptom indicates a mental illness isn't black and white. For instance, what's considered an excessive fear, say of spiders or public speaking, can vary from person to person. And in some cultures and situations, certain behaviors or thoughts may be considered normal, while in other situations they may be considered abnormal.

In general, signs and symptoms may indicate a mental illness when they cause you distress and they interfere with your ability to function in your daily life. You may have trouble coping with emotions, stress or anger, for examples. Or you may find it difficult to handle family, work or school responsibilities.

With some types of mental illness, though, such as schizophrenia or bipolar disorder, you may not realize the extent of your problems — instead, it may be family or friends who are aware that you may have a mental illness.

When to see a doctor
If you have any signs or symptoms of a mental illness, see your doctor, mental health provider or other health professional. Most mental illnesses don't get better on their own, and if untreated, they may get worse over time and cause significant problems in your life.

When you have suicidal thoughts
Suicidal thoughts and behavior are common with some mental illnesses. If you're considering suicide right now and have the means available, talk to someone immediately. The best choice is to call 911 or your local emergency services number. If you simply don't want to do that, for whatever reason, you have other choices for reaching out to someone:

• Contact a family member or friend.
• Contact a doctor, mental health provider or other health care professional.
• Contact a minister, spiritual leader or someone in your faith community.
• Go to your local hospital emergency room.
• Call a crisis center or hot line.

Helping a loved one
If you have a loved one who you think may have symptoms of mental illness, have an open and honest discussion about your concerns. You may not be able to force someone to seek professional care, but you can offer encouragement and support. You can also help your loved one find a qualified doctor or mental health provider and make an appointment. You may even be able to go to an appointment with him or her. If you have a loved one who has harmed himself or herself, or is seriously considering doing so, take him or her to the hospital or call for emergency help.

There's no specific identifiable cause of mental illness. But mental illnesses, in general, are thought to be caused by a variety of biochemical, genetic and environmental factors:

• Biochemical. Biochemical causes are related to naturally occurring processes in your body, leading some experts to characterize mental illnesses as brain disorders. This is the "nature" part of the nature vs. nurture debate. Some evidence from imaging studies indicates that people with mental illness have physical changes in their brains. The significance of these changes is still uncertain but may eventually help pinpoint causes. The naturally occurring brain chemicals called neurotransmitters, which are linked to mood, also may play a role in some mental illnesses. Hormonal imbalances also could be a culprit.
• Genes. Your genes direct all your body's functions and define you as a living human being. Some studies suggest that mental illness is linked to certain inherited genes. In fact, mental illness is more common in people whose biological family members also have a mental illness. Researchers are trying to find genes that may be involved in causing mental illness. Some research suggests that you may have a genetic vulnerability to developing a mental illness and that your life situation may trigger the actual development of a mental illness.
• Environment. Environment is also thought to play a causal role in some way. Environmental causes are situations in your life that are difficult to cope with, such as the loss of a loved one, financial problems and high stress. This is the "nurture" part of the nature vs. nurture debate.

Although the precise cause of mental illness isn't known, certain factors may increase the risk of developing or triggering mental illness, including:

• Having other biological relatives with a mental illness
• Malnutrition or exposure to viruses while in the womb, which is linked to schizophrenia
• Stressful life situations, such as financial problems, a loved one's death or a divorce
• Chronic medical conditions, such as cancer
• Combat
• Taking psychoactive drugs during adolescence
• Childhood abuse or neglect
• Lack of friendships or healthy relationships

Mental illness is common worldwide. In the United States, about one in four adults has a mental illness in any given year. And nearly half of them have more than one mental illness at the same time. Mental illness can begin at almost any age, from childhood through later adult years.

Mental illness exacts a heavy toll. It's one of the leading causes of disability. Aside from reducing your overall quality of life, untreated mental illness can result in severe emotional, behavioral, health, and even legal and financial problems. Complications that mental illness may cause or be associated with include:

• Suicide
• Substance abuse
• Homicide
• Heart disease and other medical conditions
• Work or school problems
• Family conflicts
• Relationship difficulties
• Social isolation
• Poverty
• Homelessness

In some cases, a health care provider or other professional may ask you about your mood, thoughts or behavior. Your doctor may bring it up during a routine medical appointment if you seem to be sad, agitated or angry, for instance. Or you may decide to schedule an appointment with your family doctor to talk about your concerns. In either case, because mental illness often requires specialized care, you may be referred to a mental health provider, such as a psychiatrist or psychologist, for evaluation and treatment. In other cases, you may seek out a mental health provider on your own first.

What you can do
Being an active participant in your care can help your efforts to manage your mental illness. One way to do this is by preparing for your appointment. Think about your needs and goals for treatment. Also, write down a list of questions to ask. These may include:

• What type of mental illness might I have?
• Why can't I get over mental illness on my own?
• How do you treat my type of mental illness?
• Will psychotherapy help?
• Are there medications that might help?
• How long will treatment take?
• What can I do to help myself?
• Are there any brochures or other printed material that I can take home with me?
• What Web sites do you recommend visiting?

In addition to the questions that you've prepared to ask, don't hesitate to ask questions during your appointment when you don't understand something.

What to expect from your doctor
During your appointment, your doctor or mental health provider is likely to ask you a number of questions about your mood, thoughts and behavior. You may be asked such questions as:

• When did you first notice symptoms?
• How is your daily life affected by your symptoms?
• What other treatment, if any, have you had?
• What have you tried on your own to feel better or control your symptoms?
• What things make you feel worse?
• Have family or friends commented on your mood or behavior?
• Have any relatives had a mental illness?
• What do you hope to gain from treatment?
• What medications or over-the-counter herbs and supplements do you take?

When doctors believe someone has a mental illness, they typically run a series of medical and psychological tests and exams. These can help rule out other problems that could be causing your symptoms, pinpoint a diagnosis and also check for any related complications. These exams and tests generally include:

• Physical exam. This may include measuring height and weight, checking vital signs, such as heart rate, blood pressure and temperature, listening to your heart and lungs, and examining your abdomen.
• Laboratory tests. These may include a complete blood count (CBC), screening for alcohol and drugs, and a check of your thyroid function.
• Psychological evaluation. A doctor or mental health provider talks to you about your thoughts, feelings and behavior patterns. He or she asks about your symptoms, including when they started, how severe they are, how they affect your daily life and whether you've had similar episodes in the past. You also discuss any thoughts you may have of suicide, self-harm or harming others.

Pinpointing which mental illness you have
It sometimes can be difficult to determine which particular mental illness or mental illnesses you have. For one thing, many mental illnesses share similar symptoms. Also, a diagnosis is often based largely on how you describe your symptoms, along with how your doctor interprets those symptoms and observes you behaving. Because of this, it can take some time and effort to get an accurate diagnosis. Be sure to stick with it, though, so that you can get appropriate treatment designed for your particular illness and situation.

The symptoms and clinical features for each mental illness are detailed in a book called the Diagnostic and Statistical Manual of Mental Disorders (DSM). This manual is published by the American Psychiatric Association and is used by mental health providers to diagnose mental conditions and by insurance companies to reimburse for treatment.

To be diagnosed with a particular mental illness, you must meet the criteria for that illness listed in the current version of the DSM. Mental illnesses are grouped together in the DSM based on their symptoms. The concept of mental illness is somewhat controversial, and even experts sometimes disagree about what's considered normal or abnormal mental health. The scope of what's considered a mental illness continues to evolve.

Classes of mental illness
The main classes of mental illness are:

• Mood disorders. These include disorders that affect how you feel, such as persistent sadness or feelings of euphoria. Among them are major depression, dysthymia and bipolar disorder.
• Anxiety disorders. Anxiety is an emotion characterized by the anticipation of future danger or misfortune accompanied by a feeling of being ill at ease. Examples include panic disorder, obsessive-compulsive disorder, specific phobias and generalized anxiety disorder.
• Substance-related disorders. These include problems associated with the misuse of alcohol, nicotine, caffeine and illicit drugs.
• Psychotic disorders. These disorders impair your sense of reality. The most notable example of this is schizophrenia, although other classes of disorders can be associated with psychosis at times.
• Cognitive disorders. These disorders affect your ability to think and reason. They include delirium, dementia and memory problems. One of the most recognizable is Alzheimer's disease.
• Developmental disorders. This category covers a wide range of problems that usually first begin in infancy, childhood or adolescence. They include autism, attention-deficit/hyperactivity disorder and learning disabilities. But just because they're all grouped in this category doesn't necessarily mean they share a common cause or that there's a relationship among the disorders.
• Personality disorders. A personality disorder is a lasting pattern of inner experience and behavior that is dysfunctional and leads to distress or impairment. Examples include borderline personality disorder and antisocial personality disorder.
• Other disorders. These include disorders of impulse control, sleep, sexual functioning and eating. Also included are dissociative disorders, in which your sense of self is disrupted, and somatoform disorders, in which there are physical symptoms in the absence of a clear physical cause, such as hypochondriasis.

The treatment that's best for you depends on your particular mental illness, its severity and your life situation. Often, a team approach is appropriate to make sure all of your psychiatric, medical and social needs are met, especially in cases of severe mental illness, such as schizophrenia.

Treatment teams
The team involved in treatment may include your:

• Family or primary care doctor
• Psychiatrist
• Psychotherapist
• Pharmacist
• Family members
• Social workers

If you have a mild mental illness and your symptoms are well controlled, you may need treatment from only your family doctor, a psychiatrist or a therapist.

Treatment options
Numerous treatments for mental illness are available. They include

• Medications
• Psychotherapy
• Electroconvulsive therapy (ECT)
• Hospitalization

Medications
Psychiatric medications can be an effective treatment for mental illnesses. Although psychiatric medications don't cure mental illness, they can often significantly improve symptoms, whether you have depression, schizophrenia, panic disorder or another condition. Psychiatric medications also can help make other treatments, such as psychotherapy, more effective.

In some cases, specific psychiatric medications are approved by the Food and Drug Administration (FDA) to treat a particular type of mental illness. However, medications are often used to treat conditions for which they're not officially approved — a common and perfectly legal practice called off-label use.

Here's an overview of some of the most commonly used classes of prescription psychiatric medications:

Antidepressant medications. Antidepressants are used to treat various types of depression. Several types of antidepressants, grouped by how they affect brain chemistry, are available. Antidepressants can help improve such symptoms as sadness, hopelessness, lack of energy, difficulty concentrating and lack of interest in activities. Antidepressants are often used to treat illnesses besides depression, including nonpsychiatric conditions. Antidepressant medications include citalopram (Celexa), paroxetine (Paxil, Paxil CR) and many others.

Mood-stabilizing medications. Mood stabilizer is the common name given to psychiatric medications that treat both manic and depressive symptoms. Mood stabilizers are most commonly used to treat bipolar disorder, which is characterized by alternating episodes of mania and depression. Mood stabilizers may also include anti-seizure medications. Mood-stabilizing medications include lithium (Eskalith, Lithobid), divalproex (Depakote) and many others.

Anti-anxiety medications. Anti-anxiety medications, as their name suggests, are used to treat anxiety disorders, such as generalized anxiety disorder and panic disorder. They also may be useful in helping reduce agitation and insomnia. These medications are typically fast acting, helping relieve symptoms in as quickly as 30 minutes. A major drawback, however, is that they may cause dependency. Anti-anxiety medications include alprazolam (Xanax), lorazepam (Ativan) and many others.

Antipsychotic medications. Antipsychotic medications, also called neuroleptics, are typically used to treat psychotic disorders, such as schizophrenia. Antipsychotic medications may also be used to treat severe cases of depression accompanied by psychosis. Antipsychotic medications include clozapine (Clozaril), olanzapine (Zyprexa) and many others.

Psychotherapy
Psychotherapy is a general term for the process of treating mental illness by talking about your condition and related issues with a mental health provider. During psychotherapy, you learn about your condition and your mood, feelings, thoughts and behavior. Using the insights and knowledge you gain in psychotherapy, you can learn healthy coping skills and stress management. Psychotherapy often can be successfully completed in a few months, but in the case of a severe mental illness, long-term treatment may be helpful.

There are many specific types of psychotherapy, each with its own approach to improving your mental well-being. The type of psychotherapy that's right for you depends on your individual situation.

Electroconvulsive therapy (ECT)
Electroconvulsive therapy (ECT) is a procedure in which electric currents are passed through your brain, deliberately triggering a brief seizure. This seems to cause changes in brain chemistry that can reduce symptoms of certain mental illnesses. Because it can provide significant improvements in symptoms more quickly than psychotherapy or medications, electroconvulsive therapy may be the best treatment option for some people. Deciding whether electroconvulsive therapy is a good option for you or a loved one can be extremely difficult. Make sure you understand all the pros and cons.

Hospitalization and residential treatment programs
It's not often that a mental illness becomes so severe that you require psychiatric hospitalization. Psychiatric hospitalization is generally recommended only when you aren't able to care for yourself properly or when you're in immediate danger of harming yourself or someone else. Psychiatric hospitalization options include 24-hour inpatient care, partial or day hospitalization, or residential treatment, which offers a supportive place to live.

Participating in your own care
Try to be an active participant in your treatment. Working together, you and your doctor or therapist can decide which treatment options may be best for your situation, depending on your symptoms and their severity, your personal preferences, insurance coverage, affordability, treatment side effects and other factors. In some cases, a mental illness may be so severe that a doctor, loved one or guardian may need to guide your care until you're well enough to participate in decision making.

In most cases, a mental illness won't get better if you try to treat it on your own, without professional care. But you can do some things for yourself that will build on your treatment plan. In addition to professional treatment, follow these lifestyle and self-care steps for mental illness:

• Stick to your treatment plan. Don't skip therapy sessions, even if you don't feel like going.
• Take your medications as directed. Even if you're feeling well, resist any temptation to skip your medications. If you stop, symptoms may come back. You could also experience withdrawal-like symptoms from stopping a medication too suddenly.
• Learn about your condition. Education about your condition can empower you and motivate you to stick to your treatment plan.
• Pay attention to warning signs. Work with your doctor or therapist to learn what might trigger your symptoms. Make a plan so that you know what to do if symptoms return. Contact your doctor or therapist if you notice any changes in symptoms or how you feel. Consider involving family members or friends in watching for warning signs.
• Get active. Physical activity and exercise can help manage many symptoms, such as depression, stress and anxiety. Activity can also counteract the effects of some psychiatric medications that may cause weight gain. Consider walking, jogging, swimming, gardening or taking up another form of exercise you enjoy.
• Avoid drugs and alcohol. Alcohol and illicit drugs can worsen mental illness symptoms or interact with medications.
• Get routine medical care. Don't neglect checkups or skip visits to your family doctor, especially if you aren't feeling well. You may have a new health problem that needs to be addressed, or you may be experiencing side effects of medication.

Coping with a mental illness can be challenging. Mental illness makes it hard to engage in the behavior and activities that may help you feel better. Talk to your doctor or therapist about improving your coping skills, and consider these tips to cope with mental illness:

• Simplify your life. Cut back on obligations when possible, and set reasonable schedules for goals.
• Write in a journal to express pain, anger, fear or other emotions.
• Read reputable self-help books and consider talking about them to your doctor or therapist.
• Don't become isolated. Try to participate in normal activities and get together with family or friends regularly.
• Take care of yourself by eating a healthy diet and getting sufficient sleep.
• Join a support group for people with your type of mental illness so that you can connect to others facing similar challenges.
• Stay focused on your goals. Recovery from mental illness is an ongoing process. Stay motivated by keeping your recovery goals in mind. Remind yourself that you're responsible for managing your illness and working toward your goals.
• Learn relaxation and stress management. Try such stress-reduction techniques as meditation, yoga or tai chi.
• Structure your time. Plan your day and activities. Try to stay organized. You may find it helpful to make a list of daily tasks.
• Time important decisions. Don't make important decisions when you're in the depths of mental illness, since you may not be thinking clearly.

There's no sure way to prevent mental illness. However, taking steps to control stress, to increase your resilience and to boost low self-esteem may help. Friendship and social support, especially in times of crisis, can help you weather rough spells. Also, treatment at the earliest sign of a problem can help prevent a mental illness from worsening. Long-term maintenance treatment also may help prevent a relapse of symptoms.