There is no single test for "abnormal" behavior. Clinicians judge it with several criteria together:

• Distress — the person suffers
• Dysfunction — work, relationships, or self-care are impaired
• Deviance — behavior differs markedly from cultural norms (culture must always be considered; a religious experience shared by a community is not a delusion)
• Danger — risk of harm to self or others

A mental disorder is a clinically significant disturbance in thinking, emotion regulation, or behavior that reflects dysfunction in psychological, biological, or developmental processes and is usually associated with distress or impaired functioning. Expected reactions to common stressors (for example, grief after a death) are not disorders on their own.

Psychosis means impaired reality testing — the ability to tell internal experience from external reality. Its core features are hallucinations, delusions, and disorganized thinking or speech. Persistent sadness, excessive worry, or social fear are not psychotic symptoms unless reality testing is lost.

Causes of abnormal behavior are multifactorial (genetics, brain chemistry, trauma, substances, medical illness, social stress). Always consider a medical or substance cause first, especially with sudden onset, older age, visual hallucinations, or fluctuating consciousness (delirium).

The mental status examination (MSE) is a structured snapshot of the client's present mental state.

Disordered thought process

Delusions (fixed false beliefs not shared by the culture)

Catatonia (seen in mood disorders, schizophrenia, and medical illness): stupor (no psychomotor activity, not relating to the environment), mutism, posturing (holding a position against gravity), waxy flexibility, catalepsy, negativism, echolalia (repeats others' words), echopraxia (imitates others' movements), stereotypy, and catatonic excitement (purposeless agitation).

• Treat the underlying cause (infection, drug toxicity, withdrawal, metabolic disturbance)
• Psychosis: antipsychotic medication (Topic 9). Key safety points: extrapyramidal symptoms, neuroleptic malignant syndrome, metabolic effects, QT prolongation, and a boxed warning for increased mortality in older adults with dementia-related psychosis
• Catatonia: lorazepam is first-line (often a test dose; improvement supports the diagnosis). Monitor for sedation and respiratory depression; caution with other CNS depressants and opioids. ECT if benzodiazepines fail or catatonia is malignant. Antipsychotics are used cautiously because catatonia raises the risk of NMS
• Severe agitation with imminent danger: verbal de-escalation first; medication and, as a last resort, restraint under legal rules (Topic 15)

Listed in priority order.

1. Assess danger to self and others
   • Base risk on current, specific behavior: stated intent, a specific plan, a named target, access to means (weapons), and recent escalation. A history of violence is the strongest predictor of future violence; how imminent the danger is depends on this current, specific behavior. Substance intoxication further raises risk
   • Ask directly about command hallucinations ("Are the voices telling you to do anything?"). Commands to harm self or others are an emergency
   • Early signs of escalating aggression: pacing, clenched fists, loud voice, staring, verbal threats
2. Maintain safety — reduce stimulation, keep a safe distance and a clear exit, remove dangerous objects, increase observation level
3. Rule out delirium — acute confusion with inattention is a medical emergency, not a primary psychiatric disorder
4. Communicate therapeutically with psychotic clients
   • Do not argue with or confirm delusions; acknowledge the feeling: "That sounds frightening."
   • Present reality simply: "I don't hear any voices, but I understand you do."
   • To assess reality testing, ask whether others can perceive the same thing: "Do you think other people can see the device too?"
   • Focus on real, here-and-now topics and activities
5. Catatonic clients — monitor intake and output, nutrition and hydration, skin integrity, elimination, and signs of venous thromboembolism; reposition; speak to the client as if they understand (they often do)
6. Document the MSE objectively using the client's own words in quotation marks

• Explain symptoms in plain language; hallucinations and delusions are symptoms of an illness that can be treated
• Teach families early warning signs of relapse (sleep loss, withdrawal, suspiciousness)
• Encourage avoidance of alcohol and drugs, which worsen psychosis
• Advise the family to remove firearms and secure medications when risk is present
• Provide crisis contacts (Country Notes)

• Psychosis = loss of reality testing: hallucinations, delusions, disorganized thinking
• Hallucination = no stimulus; illusion = misinterpreted real stimulus
• Thought broadcasting = own thoughts are broadcast to others; insertion = thoughts put in; withdrawal = thoughts taken out
• Delusion of control (influence) = actions or feelings controlled by an outside force
• Echolalia repeats words; echopraxia imitates movements
• Catatonic stupor = unresponsive, mute, immobile; posturing / waxy flexibility = holds positions
• Flight of ideas = mania; loose associations = schizophrenia
• Mood is what the client reports; affect is what the nurse observes
• Danger assessment rests on current specific behavior, plan, target, and means
• Never argue with a delusion; respond to the feeling, then offer reality
• Lorazepam first-line for catatonia; ECT if it fails
• Think delirium before psychiatric diagnosis in acute confusion