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Top Causes of Personality Changes

Personality changes can be caused by a mental illness like depression, bipolar disorder, or personality disorders. It may also be caused by physical illnesses like a urinary tract infection (especially in older adults), concussion, or brain tumor. Understanding the cause can help create an effective treatment.
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Last updated April 24, 2024

Personality change quiz

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Personality change quiz

Take a quiz to find out what's causing your personality change.

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A change in someone’s personality could be subtle and come on slowly, or dramatic and sudden. A person may seem more down, irritable or angry. Or they can be more activated or “hyper.” Someone can start to seem forgetful or be confused. Often these changes are noticed by family members.

Understanding the cause of personality changes can be complicated because several types of mental illnesses and medical illnesses may trigger them. It can be from depression, anxiety, or dementia. But it can also be caused by a concussion, a tumor, or even a urinary tract infection, especially in the elderly. Certain medications may also cause personality changes.

It’s important to talk with your doctor about any personality changes. Keeping a mood log—and tracking any physical symptoms you have—can help your doctor identify the cause and develop a treatment plan.

Pro Tip

There are many causes for personality changes, as well as many potential treatments. Your doctor will need your medical and psychiatric history to get a better handle on why this could be occurring. —Dr. Keerthan Somanath


1. Depression


  • Frequent low mood
  • Lack of motivation, apathy
  • Feelings of guilt, regret, or worthlessness
  • Unable to find pleasure in anything
  • Poor concentration
  • Difficulty falling or staying asleep
  • Low energy
  • Loss of appetite, potentially leading to weight loss
  • Hopelessness
  • Thoughts of suicide

Major depressive disorder, also known as clinical depression, is when you feel sad, hopeless, or detached from your daily life. It lasts for at least two weeks. You may struggle with basic tasks, such as getting out of bed or showering, and feel like nothing brings you pleasure, even activities that would normally lift your mood.

Depression is common. One in six people will get depression at some point in their lives, according to the American Psychiatric Association. The condition may be caused by abnormal levels of brain chemicals, hormonal imbalances, stress, and chronic medical conditions like heart disease.

Treating depression

Treatment may include antidepressant medication, talk therapy, and lifestyle or behavioral modifications (such as improvements in diet, sleep, and exercise).

2. Bipolar disorder


  • Decreased need for sleep
  • Engaging in risky behaviors, such as gambling, overspending, or drinking too much
  • Racing thoughts
  • Hyperverbality (talking too much)
  • Feeling elevated and elated, often followed by a period of depression
  • Feeling invincible or grandiose
  • “Cycling” between moods

People with bipolar disorder have episodes of mania or hypomania (slightly less intense) that can be followed by depression. The frequency and intensity of mania and depression can vary, so not everyone experiences it the same way. Bipolar disorder can be hard to manage on your own, and can lead to relationship problems, difficulty holding a job, and legal and financial trouble.

Causes of bipolar disorder include family history and stressful life events.

Treating bipolar disorder

Bipolar disorder can be treated with a combination of medication (such as mood stabilizers and antipsychotic drugs) and talk therapy.

3. Dementia (including Alzheimer’s disease)


Dementia is a decline in cognitive abilities that affects your short-term memory, reasoning, language, and ability to focus. These deficits interfere with being able to carry out everyday activities. People with dementia often have behavioral and personality changes. They may be sad, anxious, or clingy.

Dementia is a progressive disease, which means it gets worse with time. There are three common types of dementia:

  • Alzheimer’s disease. This creates plaques in the brain that cut off nutrients to brain neurons. It’s the most common form of dementia. It mainly affects older adults, with symptoms often occurring between ages 60 to 70.
  • Vascular dementia. In this case, dementia is caused by blocking, narrowing, or damage to blood vessels in the brain, which can occur during a stroke or brain bleed.
  • Frontotemporal dementia. This type of dementia is a progressive loss of nerve cells in the brain’s frontal and temporal lobes. Frontotemporal dementia occurs in people between ages 45 to 65.

Pro Tip

A patient with frontotemporal dementia may say, “My family has been telling me I’m behaving differently. Specifically, that I’ve been saying things to people that I normally wouldn’t say.” A patient with depression who has become withdrawn may say, “I have been feeling down and depressed.” —Dr. Somanath

Treating dementia

While dementia cannot be cured, the symptoms can be temporarily managed with medication, lifestyle and behavioral changes, and social connection and support. Existing medications are somewhat controversial. Talk to your doctor to weigh the benefits and risks of any medications.

4. Urinary tract infection


A urinary tract infection, or UTI, occurs when bacteria invade the urinary system, including the bladder. In older adults, an untreated UTI can cause temporary personality changes such as confusion and agitation.

Usually, personality changes caused by a UTI come on suddenly and go away once the UTI is treated.

Treating a UTI

Your doctor will diagnose a UTI by taking a urine sample. A UTI is treated with antibiotics.

5. Post-concussion syndrome


  • Headache
  • Decreased concentration
  • Memory problems
  • Fatigue
  • Irritability
  • Vision problems
  • Sleep disturbances

A concussion is a type of brain injury that damages brain cells and affects how your brain functions. This can lead to physical and personality changes. Your symptoms may last for a few days or a month, or they may linger for months or even years. This is called post-concussion syndrome (PCS).

There are several types of injuries that can lead to a concussion and PCS, including a car accident, a sports injury, or a fall. Older people are more likely to develop PCS following a concussion.

Treating PCS

Your doctor will diagnose PCS based on your symptom history and, in some cases, brain imaging tests. Treatment depends on the severity of your symptoms and the type of injury you have.

Lifestyle changes, such as getting more rest and limiting screen time, are recommended. You may also be referred to a specialist. For example, you may need to see a neurologist if you have problems like lack of concentration and headaches.

6. Brain tumor


A brain tumor, or mass, is an abnormal growth of tissue in the brain. Many brain tumors are benign, while others are malignant. Some tumors form in the brain, while others occur when cancer in another part of the body spreads to the brain.

Treating a brain tumor

If your doctor suspects a brain tumor, they will do a neurological exam and order imaging tests such as a CT scan or MRI. If the tumor is benign, it may or may not be treated depending on your symptoms.

Benign tumors can be removed surgically if necessary. If the tumor is malignant, it must be treated. Your doctor will recommend a combination of surgery, radiation therapy, and chemotherapy.

Other possible causes

Several other medical and psychiatric conditions can lead to changes in your personality. These include:

  • Bacterial or viral encephalitis
  • Low blood sugar
  • Side effects of certain medications
  • Psychotic disorders, such as schizophrenia or drug-induced psychosis
  • Personality disorders, such as borderline personality disorder, which can cause impulsiveness, self-destructive behaviors, chronic feelings of emptiness, and extreme mood swings
  • Aging
  • Going through a stressful situation

When to call the doctor

Call your doctor if:

  • Your personality changes affect your quality of life
  • Lifestyle changes, such as getting more sleep, don’t help with your symptoms
  • Your personality changes worry you or your loved ones

Dr. Rx

You doctor may ask you questions like: When were the personality changes noticed, for how long have they been going on, are you aware of the changes, have you recently experienced any significant medical condition(s), and have the changes had an impact on your daily functioning. —Dr. Somanath

Should I go to the ER?

You should go to the ER if you’re experiencing personality changes and any of these symptoms:

  • You feel like you may be a danger to yourself or others.
  • You’re unable to take care of your basic needs (food, clothing, shelter).
  • You’re extremely confused.
  • You’re hallucinating.
  • You have a severe headache.
  • Your speech is slurred, you have difficulty walking, or you notice symptoms such as your face drooping on one side. These may be a sign of a stroke.
  • High fever


At-home care

  • Make sure to get an adequate amount of sleep each night, maintaining the same bedtime and wake up time.
  • Minimize external stressors as much as possible.
  • Hydrate.
  • Eat regular meals.
  • Monitor your mood with a journal to note any patterns between your mood and your lifestyle.

Other treatment options

  • Talk therapy
  • Medications such as antidepressants or mood stabilizers
  • Surgery to remove a brain tumor
  • Treatments such as chemotherapy
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The stories shared below are not written by Buoy employees. Buoy does not endorse any of the information in these stories. Whenever you have questions or concerns about a medical condition, you should always contact your doctor or a healthcare provider.
Dr. Somanath graduated from the University of Texas at Austin with honors, completing a bachelor's degree in Electrical Engineering and a minor in Mathematics. He subsequently worked as a software engineer at National Instruments in Austin, Texas, where he developed an interest in neuroscience, and eventually medicine after working with one of the company's clients. Dr. Somanath completed residenc...
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