What is a mental illness?

A mental illness is a condition that impacts a person's thinking, feeling or mood, as defined by the National Alliance on Mental Illness. Mental illness may affect a person's ability to relate to others and function on a daily basis. Mental illnesses include ADHD, bipolar disorder, post-traumatic stress disorder, depression and schizophrenia, among others.

Mental health conditions can have multiple causes, including genetics, lifestyle and environment, explains the National Alliance on Mental Illness. For example, stressful situations or traumatic events can trigger mental health conditions, and the person's genetics may also predispose her to certain conditions.

To diagnose a mental illness, doctors usually perform a physical exam, request lab work and/or perform a psychiatric evaluation, according to Mayo Clinic. Treatment depends on the type of mental illness. Treatment options may include medication and/or psychotherapy. Hospitalization may also be necessary in cases where other options have failed.

Although mental illnesses often require professional care, various lifestyle changes can help improve mental health conditions, according to Mayo Clinic. These lifestyle strategies include sticking to the treatment plan prescribed by the doctor, avoiding alcohol and drugs, and staying active. Experts also advise those with mental illnesses to refrain from making any important decisions while experiencing severe symptoms.