Your personality can gradually change throughout your life. Fluctuations in mood from time to time are normal. However, unusual personality changes may be a sign of a medical or mental disorder.

A personality change can be demonstrated in a variety of ways.

For example, a behavior that’s inconsistent with how you would typically react under said circumstances indicates a personality change.

A person behaving in an uncharacteristically moody, aggressive, or euphoric manner, inconsistent with their usual way of behaving in similar situations also demonstrates a personality change.

Being nonchalant in situations that would normally cause stress or aggravation is an example of a personality change.

Another example is being happy to hear tragic news.

While a gradual personality change isn't unusual, a sudden change can be caused by an injury or illness.

Look for the following signs to determine if strange or unusual behavior is an emergency situation:

  • weak pulse
  • clammy skin
  • rapid heart rate
  • rapid breathing
  • shallow breathing
  • low blood pressure
  • confusion
  • dizziness
  • lightheadedness
  • difficulty talking
  • shooting pains in the arms or legs
  • pain in the chest
  • visual changes

If you or someone else experiences any of these symptoms, seek medical attention immediately. Don’t drive yourself to a hospital. Call 911.

Grief, bad news, and disappointment can cause a normally happy person to become downtrodden. Sometimes, a person’s mood can be altered for weeks or months after hearing devastating news. However, mood changes aren’t the same as personality changes.

However, some people experience unusual or strange behavior for years, which may occur due to an illness or injury. A person may experience a change in their demeanor after experiencing a traumatic situation or witnesses an unpleasant event.

These behavioral changes may be caused by a mental health condition, such as:

  • Anxiety: Anxiety occurs when a person feels nervous or uneasy about a situation. It’s normal to experience some anxiety, but when it occurs on a regular basis without provocation, it may be a sign of generalized anxiety disorder.
  • Panic attacks: Panic attacks are periods of extreme fear. Sometimes, the fear seems to be irrational. Such situations include a person having a panic attack when seeing an elevator or speaking in public.
  • Post-traumatic stress disorder: Also called PTSD, this is a mental health condition marked by extreme fear, flashbacks, and in some cases, hallucinations. PTSD is triggered by memories of trauma, such as a terrorist attack or car accident.
  • Bipolar disorder: Bipolar disorder causes a person to have extreme fluctuations in mood. Mood changes can include euphoria and extreme depression and may alter the way a person responds to certain interactions or situations, depending on their mood state.
  • Schizophrenia:Schizophrenia makes it difficult to think clearly, to effectively comprehend situations, to behave as normally in social situations, and to distinguish between what is and isn’t real.

Medical conditions that cause a fluctuation in hormone levels can also cause strange or unusual behavior. These conditions include:

Medical emergencies can also cause strange or unusual behavior. These situations include:

Other medical conditions or circumstances that may cause personality changes include:

Frontal lobe damage personality changes

An injury to the frontal lobe of the brain, located underneath the forehead, may lead to symptoms including a personality change.

The frontal lobe is the "control panel" for our personality. It’s also responsible for our:

  • speech
  • emotional expression
  • cognitive skills

The most common brain injury is damage to the frontal lobe. Among the possible causes are:

  • blows to the head
  • falls
  • car accidents

Find out more about the causes, symptoms, and treatment of brain damage.

Personality change after stroke

After you experience a stroke, during which a blood vessel in your brain ruptures or the oxygen supply to your brain is interrupted, you may have symptoms including a personality change.

Some stroke survivors experience apathy. They don't seem to care about anything.

Others, especially survivors of strokes that occur in the brain's right hemisphere, may neglect one side of their body or objects. For example, they may ignore one side of their body or food on one side of a plate.

Following a frontal lobe or right hemisphere stroke, some people may experience impulsive behavior. This may include being unable to think ahead or understand the consequences of their actions.

Get a better understanding of the symptoms of a stroke.

Brain tumor personality changes

A brain tumor in the frontal lobe, temporal lobe, or parts of the cerebrum can cause personality changes.

For example, someone who was easy to get along with could become irritable. An active person could become more passive.

Mood swings, such as quickly becoming angry after feeling happy, may also occur.

Find out more about brain tumors and their symptoms.

Personality changes with dementia

Dementia, which is caused by illness or injury, is an impairment of at least two cognitive brain functions.

Cognitive brain functions include:

  • memory
  • thinking
  • language
  • judgment
  • behavior

The loss of neurons (cells) in the frontal lobe of the brain can cause people with mild dementia to experience personality changes such as becoming more withdrawn or depressed.

People with moderate dementia may experience more significant personality changes, such as becoming agitated and suspicious of others.

Learn more about the symptoms, causes, and treatment for dementia.

Adderall and personality changes

The prescription drug Adderall is the brand name for the combination of dextroamphetamine and amphetamine. It’s mainly used to treat attention deficit hyperactivity disorder (ADHD).

Among the reported side effects of stimulants like Adderall are new or increased hostility and aggressive behavior. However, this appears to be related to misuse of the medication.

Children and teenagers may have new psychotic or manic episodes.

Find out more about the effects of Adderall on the body.

Alcohol addiction personality changes

Alcohol addiction, also called alcoholism, is a disease that changes the brain and neurochemistry. These developments can cause a change in personality.

People with alcohol addiction may become increasingly depressed and lethargic. They may have lowered inhibitions and impaired judgment. They become verbally or physically abusive.

Learn more about the symptoms and treatment for alcohol addiction.

Personality changes with age

Your personality can continue to develop throughout your lifetime.

A 2011 study suggests that the "Big Five" personality traits — conscientiousness, agreeableness, neuroticism, openness, and introversion/extroversion — remain stable once people reach adulthood.

In a 2016 study, researchers compared the results of personality tests taken by adolescents in 1950 with those taken by the same people at age 77. The test results suggested that personality may gradually change during someone's life and be very different by the time they're older.

This study did have some methodology limitations, and more work is needed in this area.

Personality changes in the elderly

Minor personality changes in older adults, such as becoming more irritable or agitated, are not unusual. Extreme personality changes, such as a passive person becoming very controlling, could be a sign of dementia due to changes in the brain's frontal lobe.

A 2016 study suggests that older adults have different personality traits than those of younger people. For example, neuroticism tended to increase in adults in their 80s.

Some people may revert to a younger age as they grow older. This could be a sign of depression or a way to cope with aging.

Get a better understanding of the types of age regression.

Personality changes after concussion

A concussion is a mild traumatic brain injury (TBI) caused by an impact to your head. Sometimes the symptoms may linger in what is known as post-concussion syndrome.

Symptoms may include:

  • dizziness
  • headaches
  • a personality change, in some cases

An injury to the brain may affect how you understand and express emotions. It could also result in a personality change due to your emotional reaction to the changes in your life brought about by the brain injury.

Therapy or counseling may help you understand your personality change.

Learn more about the symptoms and treatments for post-concussion syndrome.

Personality changes after heart attack

While it’s not uncommon to feel anxious or depressed after a heart attack, these feelings are usually only temporary. However, some people may continue to feel depressed for weeks after the heart attack.

Up to 33 percent of people who've had heart attacks experience depression to some degree.

If your depression is severe, you should see a healthcare provider. Without treatment, it could lead to an increased risk for another heart attack.

Find out more about the causes, symptoms, and treatment for a heart attack.

Do antidepressants change your personality?

Antidepressant medications are commonly prescribed to treat major depressive disorder and generalized anxiety disorder. Among their side effects may be personality changes.

A 2012 study suggests that people who take Paxil, a selective serotonin reuptake inhibitor (SSRI), not only become less depressed but also become more confident and outgoing.

The more extreme the personality change, the less likely the person would have relapses. However, more research in this area is needed.

Learn more about the side effects of antidepressants.

Lyme disease personality changes

Some of the symptoms of Lyme disease, which is transmitted to people from the bite of an infected blacklegged tick, may include physical signs, such as a rash, and psychological signs, including mood swings.

In a 2012 study, nearly a quarter (21 percent) of people in the early stages of Lyme disease reported feeling irritable. Roughly 10 percent of the people said they felt anxious.

Get a better understanding of the symptoms of Lyme disease.

Parkinson's personality changes

Parkinson's disease is a neurological disorder that can cause motor problems such as tremors and stiffness. It can also lead to what’s sometimes called "Parkinson's personality" due to the changes in the brain.

People with advanced Parkinson's may become:

  • apathetic
  • pessimistic
  • inattentive

They may develop what’s known as Parkinson's disease dementia.

Even in the earlier stages of the disease, people may become more depressed, obsessive, or stubborn.

Learn how to recognize the symptoms of Parkinson's disease.

Personality changes during menopause

Along with hot flashes and weight gain, menopause may cause changes in a woman's personality.

The decreased production of estrogen during menopause reduces the level of serotonins produced in your brain. Serotonins are chemicals that help regulate your moods.

As a result of these chemical changes, some women may feel:

Menopause symptoms typically continue for up to 4 years after a woman's last period.

Personality change after surgery

A 2017 study suggests it's possible that changes to the brain may last after people are given general anesthesia for surgery. For some people, changes in behavior are temporary, while the changes persist for others.

After surgery, some people may feel more confused or disoriented. Others, who are older, may experience POCD (postoperative cognitive dysfunction). POCD memory issues may be caused by the surgery rather than the anesthesia.

Find out more about the side effects of general anesthesia.

While our moods and behavior naturally fluctuate, someone with a personality change may not be acting like their usual self and may show extreme changes in behavior.

Some of the symptoms of a personality change may include:

  • new symptoms of anxiety or changes in mood
  • anger threshold
  • insensitive or rude behavior
  • impulsive behavior
  • delusions

If you’ve been experiencing a personality change, speak to your healthcare provider about it. Make sure to note:

  • when the personality change began
  • what time of day you experience it
  • what triggers it
  • whether it happens after taking prescription medication (bring the medication with you)
  • if you’re taking drugs
  • if you’re using alcohol
  • if you have a history of mental health conditions
  • if your family has a history of mental health conditions
  • any other symptoms you may be experiencing
  • if you have any underlying medical conditions

The answers to these questions will be extremely helpful to your healthcare provider. They’ll help diagnose the cause of your unusual behavior. They’ll also help your healthcare provider determine whether it’s a mental health or medical issue.

They may choose to order some tests.

The tests may include a complete blood count, glucose level test, hormone profile, and tests for infections.

Depending on the circumstances, your healthcare provider may also order imaging studies such as a CT scan or an MRI.

If you don’t have any identifiable medical conditions, your doctor will likely refer you to a mental health professional.

A personality change caused by a medical condition may subside once the condition is treated. However, in some cases, it won’t go away with treatment of the underlying condition.

In this case, your condition may be treated separately using mood-altering medications, depending on the cause.

If you have a hormonal imbalance, your personality change may subside after you take the prescribed medications to balance your hormones. Replacement estrogen, low-dose birth control pills, and progesterone injections are commonly prescribed medications.

Mental health conditions may be treated with a combination of mood-altering medications and therapy. Healthcare providers typically prescribe medications to treat conditions such as anxiety disorder, panic disorder, PTSD, and bipolar disorder.

Your healthcare provider might also recommend psychotherapy, or talk therapy, to help you learn to cope with stressful situations.