The observation of strange behavior depends at least in part upon the perceptions of the observer. For most people, behaviors that are observed as out of the ordinary or strange are a feature of psychotic disorders, mood disorders, and other mental-health conditions. Examples of conditions in which psychosis (altered perception of reality) are present include schizophrenia, delusional disorder, and schizoaffective disorder. People suffering from psychosis may have an altered perception of reality that often affects their behavior, leading them to act in ways that may be perceived as strange. Problems controlling one's behavior can also occur as a result of brain damage or disorders. People suffering from dementia may display strange behaviors. Behavioral changes can be accompanied by other psychiatric symptoms or by physical symptoms if they are related to a medical condition. Substance abuse and drug overdoses can also lead to problems with behavior.
Other causes of unusual behavior
- Brain Trauma
- Catastrophic Life Events
- Conduct Disorder
- Delusional Disorder
- Drug-Induced Psychosis
- Oppositional Defiant Disorder
Pictures, Images, Illustrations & Quizzes
Alzheimer's Disease Symptoms & Early Diagnosis
Memory loss and confusion can be signs of normal aging, but also warning signs of Alzheimer's disease. The early stages of...
Autism Signs in Children: What Is Autism Spectrum Disorder?
What is autism? Learn about the signs, symptoms, and diagnosis of autism spectrum disorder. Get information about the causes of...
Bipolar Disorder: Symptoms, Testing for Bipolar Depression
Bipolar disorder (once called manic depression) causes extreme mood shifts and can be disorienting. Our experts define bipolar...
Dementia, Alzheimer's Disease, and Aging Brains
What is dementia? Learn about dementia disorders such as Lewy Body Dementia, Alzheimer's disease (AD), Vascular (multi-infarct)...
Panic Attacks (Panic Disorder) Quiz: Test Your Mental Health IQ
Could you suffer a panic attack? Take this Panic Attacks Quiz to learn causes, symptoms, and treatments for panic disorder. Use...
Parkinson's Disease: Symptoms, Causes, Stages, Treatment
Discover the symptoms, causes, stages, and treatment options for Parkinson's disease. Learn more about the stages of Parkinson's...
Schizophrenia: Symptoms, Types, Causes, Treatment
What is schizophrenia? Learn about schizophrenia symptoms, signs, and treatment. Read about schizophrenia types such as paranoid...
Stroke Causes, Symptoms, and Recovery
What is a stroke? Learn about stroke symptoms like sudden numbness or weakness, confusion, vision problems, or problems with...
Teen Drug Abuse: Warning Signs, Statistics, and Facts
Teen drug abuse is a growing concern today. Learn statistics, facts, warning signs, and effects related to teen substance abuse...
Causes of Unusual Behavior
Alcoholism and Alcohol Abuse
Alcoholism is a disease that includes alcohol craving and continued drinking despite repeated alcohol-related problems, such as losing a job or getting into trouble with the law. It can cause myriad health problems, including cirrhosis of the liver, birth defects, heart disease, stroke, psychological problems, and dementia. Counseling and a few medications can be effective for alcoholism treatment.
Alzheimer's disease is a common cause of dementia. Symptoms and warning signs of Alzheimer's disease include memory loss, difficulty performing familiar tasks, disorientation to time and place, misplacing things, and more. The biggest risk factor for Alzheimer's disease is increased age. Treatment for Alzheimer's is often targeted toward decreasing the symptoms and progression of the disease.
Anxiety is a feeling of apprehension and fear characterized by symptoms such as trouble concentrating, headaches, sleep problems, and irritability. Anxiety disorders are serious medical illnesses that affect approximately 19 million American adults. Treatment for anxiety may incorporate medications and psychotherapy.
Autism Spectrum Disorder (in Children and Adults)
Autism in children and adults is a developmental disorder, characterized by impaired development in communication, social interaction, and behavior. Autism is classified as a pervasive developmental disorder (PDD), which is part of a broad spectrum of developmental disorders affecting young children and adults. There are numerous theories and studies about the cause of autism. The treatment model for autism is an educational program that is suitable to an individual's developmental level of performance. There is no "cure" for autism.
Bipolar disorder (or manic depression) is a mental illness characterized by depression, mania, and severe mood swings. Treatment may incorporate mood-stabilizer medications, antidepressants, and psychotherapy.
Brain and Spinal Cord Tumors in Adults (Symptoms, Signs, Causes, Treatment Options, Life Expectancy)
Brain and spinal tumor are diseases in which cancer (malignant) cells begin to grow in the tissues of the brain. Tumors that start in the brain are called primary brain tumors. Tumors that start in the brain and spread to other organs are called primary brain tumors. Symptoms may include headaches, personality changes, dizziness, and trouble walking. Treatment depends upon the type and grade of tumor.
Brain Tumor: Warning Symptoms, Types, Causes, Treatments, and Cure
A brain tumor can be either non-cancerous (benign) or cancerous (malignant), primary, or secondary. Common symptoms of a primary brain tumor are headaches, seizures, memory problems, personality changes, and nausea and vomiting. Causes and risk factors include age, gender, family history, and exposure to chemicals. Treatment is depends upon the tumor type, grade, and location.
Dementia is defined as a significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning. There are several different types of dementia, including cortical, subcortical, progressive, primary, and secondary dementias. Other conditions and medication reactions can also cause dementia. Dementia is diagnosed based on a certain set of criteria. Treatment for dementia is generally focused on the symptoms of the disease.
Depression is an illness that involves the body, mood, and thoughts and affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about things. The principal types of depression are major depression, dysthymia, and bipolar disease (also called manic-depressive disease).
Drug addiction is a chronic disease that causes drug-seeking behavior and drug use despite negative consequences to the user and those around him. Though the initial decision to use drugs is voluntary, changes in the brain caused by repeated drug abuse can affect a person's self-control and ability to make the right decisions and increase the urge to take drugs. Drug abuse and addiction are preventable.
Dysthymia is a less severe form of chronic depression. Symptoms and signs include insomnia, suicidal thoughts, guilt, empty feeling, loss of energy, helplessness, sluggishness, and persistent aches and pains. Treatment may involve psychotherapy, electroconvulsive therapy, and antidepressants.
Human Immunodeficiency Virus (HIV)
HIV (human immunodeficiency virus) infection left untreated causes AIDS (acquired immunodeficiency syndrome). Still incurable, AIDS describes immune system collapse that opens the way for opportunistic infections and cancers to kill the patient. Early symptoms and signs of HIV infection include flu-like symptoms and fungal infections, but some people may not show any symptoms for years. Highly active antiretroviral therapy (ART) is the standard treatment for HIV infection. These combination drug regimens have made HIV much less deadly, but a cure or vaccine for the pandemic remains out of reach. HIV is usually transmitted through sexual contact or sharing IV drug needles, but can also infect someone through contact with infected blood. Sexual abstinence, safe sex practices, quitting IV drugs (or at least using clean needles), and proper safety equipment by clinicians and first responders can drastically reduce transmission rates for HIV/AIDS.
Huntington's disease is the result of degeneration of neurons in areas of the brain. Huntington's disease is an inherited disorder. Early symptoms include mood swings, apathy, depression, and anger uncharacteristic of the individual. Judgement, memory, and other cognitive functions may become impaired. Presymptomatic testing is available for individuals who have a family history of Huntington's disease. Treatment includes medication and therapy for symptoms.
Panic attacks are sudden feelings of terror that strike without warning. These episodes can occur at any time, even during sleep. A person experiencing a panic attack may believe that he or she is having a heart attack or that death is imminent. The fear and terror that a person experiences during a panic attack are not in proportion to the true situation and may be unrelated to what is happening around them. Most people with panic attacks experience several of the following symptoms: racing heartbeat, faintness, dizziness, numbness or tingling in the hands and fingers, chills, chest pains, difficulty breathing, and a feeling of loss or control. There are several treatments for panic attacks.
Parkinson's disease is a slowly progressive neurological disease characterized by a fixed inexpressive face, a tremor at rest, slowing of voluntary movements, a gait with short accelerating steps, peculiar posture and muscle weakness, caused by degeneration of an area of the brain called the basal ganglia, and by low production of the neurotransmitter dopamine. Most patients are over 50, but at least 10 percent are under 40.
Peanut allergies causes signs and symptoms that include hives, itching, redness, and a rash. Severe reactions may cause decreased blood pressure, lightheadedness, difficulty breathing, nausea, and behavioral changes. Someone with a peanut allergy should have an EpiPen with them at all times.
Phobias are unrelenting fears of activities (social phobias), situations (agoraphobia), and specific items (arachnophobia). There is thought to be a hereditary component to phobias, though there may be a cultural influence or they may be triggered by life events. Symptoms and signs of phobias include having a panic attack, shaking, breathing troubles, rapid heartbeat, and a strong desire to escape the situation. Treatment of phobias typically involves desensitization, cognitive behavioral therapy, and medications such as selective serotonin reuptake inhibitors and beta-blockers.
Post-traumatic Stress Disorder
Post-traumatic stress disorder (PTSD), a psychiatric condition, can develop after any catastrophic life event. Symptoms include nightmares, flashbacks, sweating, rapid heart rate, detachment, amnesia, sleep problems, irritability, and exaggerated startle response. Treatment may involve psychotherapy, group support, and medication.
Postpartum depression is a form of depression that occurs within a year after delivery. It is thought that rapid hormone changes after childbirth may lead to depression. Symptoms of postpartum depression include crying a lot, headaches, chest pains, eating too little or too much, sleeping too little or too much, withdrawal from friends and family, and feeling irritable, sad, hopeless, worthless, guilty, and overwhelmed. Treatment typically involves talk therapy and medication.
Psychotic disorders are a group of serious illnesses that affect the mind. Different types of psychotic disorders include schizophrenia, schizoaffective disorder, schizophreniform disorder, brief psychotic disorder, shared psychotic disorder, delusional disorder, substance-induced psychotic disorder, paraphrenia, and psychotic disorders due to medical conditions.
Schizoaffective disorder is a mental illness that features schizophrenia and a mood disorder, either major depression or bipolar disorder. Symptoms include agitation, suicidal thoughts, little need for sleep, delusions, hallucinations, and poor motivation. Treatment may involve psychotherapy, medication, skills training, or hospitalization.
Schizophrenia is a disabling brain disorder that may cause hallucinations and delusions and affect a person's ability to communicate and pay attention. Symptoms of psychosis appear in men in their late teens and early 20s and in women in their mid-20s to early 30s. With treatment involving the use of antipsychotic medications and psychosocial treatment, schizophrenia patients can lead rewarding and meaningful lives.
Schizotypal Personality Disorder
Schizotypal personality disorder is characterized by odd behaviors, feelings, perceptions, and ways of relating to others that interfere with one's ability to function. Medication and psychotherapy can help the sufferer to manage their symptoms.
Seasonal Affective Disorder (SAD)
Seasonal affective disorder is a type of depression that tends to occur as the days grow shorter in the fall and winter. Symptoms of seasonal affective disorder include tiredness, fatigue, depression, irritability, body aches, poor sleep, and overeating.
Epilepsy is a brain disorder in which the person has seizures. There are two kinds of seizures, focal and generalized. There are many causes of epilepsy. Treatment of epilepsy (seizures) depends upon the cause and type of seizures experienced.
A stroke is an interruption of the blood supply to part of the brain caused by either a blood clot (ischemic) or bleeding (hemorrhagic). Symptoms of a stroke may include: weakness, numbness, double vision or vision loss, confusion, vertigo, difficulty speaking or understanding speech. A physical exam, imaging tests, neurological exam, and blood tests may be used to diagnose a stroke. Treatment may include administration of clot-busting drugs, supportive care, and in some instances, neurosurgery. The risk of stroke can be reduced by controlling high blood pressure, high cholesterol, diabetes, and stopping smoking.
Examples of Medications for Unusual Behavior
- aripiprazole (Abilify, Aristrada)
- chlorpromazine - oral, Thorazine
- chlorpromazine-injection, Thorazine
- Citalopram (Celexa)
- clozapine (Clozaril, Fazacio ODT, Versacloz)
- Cymbalta (duloxetine)
- desvenlafaxine (Pristiq, Khedezla)
- fluoxetine (Prozac, Sarafem, Prozac Weekly)
- fluphenazine (Permitil, Prolixin)
- fluphenazine concentrate - oral, Prolixin
- fluphenazine liquid - oral, Prolixin
- haloperidol (Haldol)
- Lexapro (escitalopram)
- olanzapine (Zyprexa, Zydis)
- paroxetine (Paxil, Pexeva)
- quetiapine (Seroquel)
- risperidone, Risperdal; Risperdal Consta, Risperdal M-TAB
- thiothixene - oral, Navane
- venlafaxine, Effexor XR (Effexor has been discontinued in the US)
- Wellbutrin (bupropion)
- ziprasidone (Geodon)
- Zoloft (sertraline)