Some Causes and Features of Personality and Behavior Changes
Cause |
Common Features* |
Tests |
Mental disorders |
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Symptoms that occur in episodes lasting a few weeks to a few months and that include mania, depression, or both Episodes of mania: Episodes of depression: |
A doctor's examination |
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Episodes of depression as described in bipolar disorder (see above) without a history of mania |
A doctor's examination |
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Usually symptoms that develop slowly, with mildly disorganized thinking and difficulty coping with daily routines Later symptoms: |
A doctor's examination |
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Drugs |
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Use of a drug, particularly |
Agitation and sometimes panic or aggression Sometimes hallucinations With long-term use of alcohol: With long-term use of amphetamines: With short-term excessive use of amphetamines or cocaine: |
A doctor's examination Sometimes blood or urine tests to detect the drug Sometimes EEG (which records the brain’s electrical activity) |
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Withdrawal of a drug, particularly |
Typically significant confusion and delirium Shaking (tremors), headache, sweating, fever, and a rapid heart rate or palpitations Sometimes seizures, hallucinations, and sleep disturbances Usually in people known to use the drug |
A doctor's examination Sometimes blood or urine tests to check for drugs |
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Side effects of a drug |
Vary, depending on the drug Drugs with anticholinergic effects, such as |
A doctor's examination Sometimes stopping the drug to see whether the symptom goes away |
Brain disorders |
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Symptoms that progress slowly Loss of short-term memory, difficulty finding the right words, and poor judgment Difficulty with daily activities (such as balancing a checkbook or finding their way around their neighborhood) Usually in people over 60 |
A doctor's examination Detailed testing of mental function involving a series of questions and tasks (neuropsychologic testing) |
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Brain infections such as |
Headache Usually confusion and fever Pain and/or stiffness when the doctor bends the neck forward (more common in people with meningitis) With herpes simplex encephalitis, hallucinations of bad odors and sometimes seizures |
A spinal tap (lumbar puncture) Often CT or MRI of the brain Culture of samples of blood, urine, and material from the throat |
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Head injuries (such as postconcussion syndrome) |
Forgetfulness and headaches Emotional instability in the weeks after a significant head injury |
CT or MRI of the brain Testing of IQ and executive functions such as the ability to plan and solve problems (neurocognitive testing) |
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Brain tumors or bleeding in the brain (brain hemorrhage) |
With brain tumors, a headache that develops gradually and is often worse during the night or early morning and when lying flat With hemorrhage, a headache that starts suddenly (called a thunderclap headache) Often confusion and drowsiness Sometimes seizures |
CT or MRI of the brain |
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Weakness and/or numbness that comes and goes in different parts of the body Sometimes partial loss of vision or double vision Sometimes symptoms that are worsened by heat (such as a warm bath or hot weather) |
MRI of the brain and spinal cord Sometimes a spinal tap Nerve conduction studies (measuring how fast nerves transmit signals) and electromyography (stimulating muscles and recording their electrical activity) |
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Tremors of the hands and fingers while they are at rest Stiffness and difficulty moving and maintaining balance Slowed speech and limited facial expressions |
A doctor's examination |
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Seizure disorders (typically complex partial seizures) |
Episodes of abnormal behavior Usually confusion and staring Sometimes involuntary chewing, smacking of the lips, and purposeless movements of the limbs Typically no loss of consciousness and no general shaking of the body (convulsions) Sometimes hallucinations of odor or taste |
MRI of the brain EEG |
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Symptoms that appear suddenly Usually weakness or paralysis on one side of the body and unsteadiness when walking |
CT or MRI of the brain |
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Bodywide (systemic) disorders |
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Hypoglycemia (a low level of blood sugar) |
Weakness, sweating, and confusion Almost always in people taking drugs for diabetes |
Tests to measure the blood sugar (glucose) level |
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Swelling of the legs, loss of appetite, and nausea Weakness that typically develops over several weeks |
Blood and urine tests to evaluate how well the kidneys are functioning |
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Yellow color of the skin and/or whites of the eyes (jaundice) Usually swelling of legs and/or abdomen A reddish purple rash of tiny dots (petechiae) Usually in people already known to have a liver disorder |
Blood tests to evaluate how well the liver is functioning (liver tests) |
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Systemic lupus erythematosus (lupus) |
Usually painful, swollen joints Often a rash, particularly on the face or areas exposed to sunlight Sometimes a headache |
Blood tests to check for certain antibodies |
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Thyroid disorders, including
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Typically in hyperthyroidism: Palpitations, excessive sweating, difficulty tolerating heat, an increased appetite, weight loss, shakiness (tremor), and sometimes bulging eyes Typically in hypothyroidism: Fatigue, constipation, difficulty tolerating cold, decreased appetite, weight gain, slow speech, sluggishness, a puffy face, drooping eyelids, coarse and thick dry skin, and loss of eyebrow hair |
Blood tests to evaluate how well the thyroid gland is functioning |
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Vitamin deficiency, such as deficiency of thiamin or vitamin B12 |
Disorientation, an impaired memory, and irritability Abnormal sensations in the hands and feet Other symptoms, depending on which vitamin is deficient |
Blood tests to measure vitamin levels |
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* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present. |
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CT = computed tomography; EEG = electroencephalography; IQ = intelligence quotient; MRI = magnetic resonance imaging; PET = positron emission tomography. |
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