While symptoms vary, and each person with mental illness is different, all people with mental illness have some of the thought, feeling, or behavioral characteristics listed below. While a single symptom or isolated event is not necessarily a sign of mental illness, multiple or severe symptoms may indicate a need for a medical evaluation.

Changes in thinking or perceiving

  • Hallucinations
  • Delusions
  • Excessive fears or suspiciousness
  • Inability to concentrate

Changes in mood

  • Sadness coming out of nowhere; unrelated to events or circumstances
  • Extreme excitement or euphoria
  • Pessimism, perceiving the world as gray and lifeless
  • Expressions of hopelessness
  • Loss of interest in once pleasurable activities
  • Thinking or talking about suicide

Changes in behavior

  • Sitting and doing nothing
  • Friendlessness; abnormal self-involvement
  • Dropping out of activities; decline in academic or athletic performance
  • Hostility, from one formerly pleasant and friendly
  • Indifference, even in highly important situations
  • Inability to express joy
  • Inappropriate laughter
  • Inability to concentrate or cope with minor problems
  • Irrational statements
  • Peculiar use of words or language structure
  • Excessive fears or suspiciousness
  • Drug or alcohol abuse
  • Forgetfulness and loss of valuable possessions
  • Attempts to escape through geographic change; frequent moves or hitchhiking trips
  • Bizarre behavior (skipping, staring, strange posturing)
  • Unusual sensitivity to noises, light, clothing

Physical changes

  • Hyperactivity or inactivity or alternations of these
  • Deterioration in hygiene or personal care
  • Unexplained weight gain or loss
  • Sleeping too much or being unable to sleep

Often the symptoms of mental illness are cyclic, varying in severity from time to time. The duration of an episode also varies; some people are affected for a few weeks or months while for others the illness may last many years or for a lifetime.

There is no reliable way to predict what the course of the illness may be. Symptoms may change from year to year. Also, one person's symptoms may be very different from those of another although the diagnosis may be the same. In some cases of apparent mental illness, other diseases such as hypothyroidism, multiple sclerosis, or a brain tumor are found to be the cause.

A thorough physical examination should be the first step when mental illness is suspected.

Please note: This guide is for informational purposes only. It is not meant to be used as a diagnostic tool. It is very important that you seek a professional evaluation if you have concerns about yourself or a loved one.