Personality and behavior changes

[Sarah]

Healthy people differ significantly in their overall personality, mood, and behavior. Each person also varies from day to day, depending on the circumstances. However, a sudden, major change in personality and/or behavior, particularly one that is not related to an obvious event (such as taking a drug or losing a loved one), often indicates a problem.
(See also Overview of Mental Illness.)
Changes in personality and behavior can be roughly categorized as one of the following:

Confusion or delirium
Delusions
Disorganized speech or behavior
Hallucinations
Mood extremes (such as depression or mania)

These categories are not disorders. They are just one way doctors organize different types of abnormal thought, speech, and behavior. These changes in personality and behavior can be caused by physical or mental health problems.
People may have more than one type of change. For example, people with confusion due to a drug interaction sometimes have hallucinations, and people with mood extremes may have delusions.