What is a sign that a person my need of mental disorder

In Adults, Young Adults and Adolscents:

Confused thinking Prolonged depression (sadness or irritability) Feelings of extreme highs and lows Excessive fears, worries and anxieties Social withdrawal Dramatic changes in eating or sleeping habits Strong feelings of anger Strange thoughts (delusions) Seeing or hearing things that aren't there (hallucinations) Growing inability to cope with daily problems and activities Suicidal thoughts Numerous unexplained physical ailments Substance use

In Older Children and Pre-Adolescents:

Substance use Inability to cope with problems and daily activities Changes in sleeping and/or eating habits Excessive complaints of physical ailments Changes in ability to manage responsibilities - at home and/or at school Defiance of authority, truancy, theft, and/or vandalism Intense fear Prolonged negative mood, often accompanied by poor appetite or thoughts of death Frequent outbursts of anger

In Younger Children:

Changes in school performance Poor grades despite strong efforts Changes in sleeping and/or eating habits Excessive worry or anxiety (i.e. refusing to go to bed or school) Hyperactivity Persistent nightmares Persistent disobedience or aggression Frequent temper tantrums