Personality changes: Do I have a personality disorder?

Naomi Carr
Author: Naomi Carr Medical Reviewer: Morgan Blair Last updated:

The way people behave, feel, and think makes up their personality. People may experience changes in certain personality traits throughout their life, but a sudden and dramatic personality and behavior change can be a cause for concern. Personality changes can occur for many reasons, which can be diagnosed and treated by healthcare professionals.

Can you change your personality?

Personality is a combination of an individual’s thoughts, emotions, and behaviors and can comprise of several traits or characteristics [1].

Changes in personality traits can be impacted by age, experience, and genetics. Research indicates that most changes in personality traits can occur at any age. While it is common for these individual characteristics to change somewhat throughout the lifespan, it is generally thought that a person’s personality remains relatively stable from adulthood [2][3].

Although personality traits can change throughout life, it is not possible to develop an entirely new personality. It is usual for people’s moods and behaviors to differ depending on the context or circumstance. However, a dramatic change in mood, behavior, or thinking, which may emerge gradually or suddenly, may indicate a serious issue [4].

What can cause personality changes?

Personality changes can occur due to numerous physical and mental health conditions. Similarly, substances, medications, and treatments for various illnesses could result in personality changes or other side effects.

Physical health conditions that affect the brain and cause personality changes include:

Traumatic brain injuries

Head injuries can have different effects on personality depending on the area of the brain affected and the severity of the damage. Personality changes that can occur include [5]:

  • Aggression
  • Irritability
  • Mood swings
  • Restlessness
  • Impaired concentration, memory, and understanding
  • Confusion
  • Changes in communication
  • Impulsive behaviors


Various types of dementia can cause different symptoms. Some of the behavior and personality changes that may be seen in an individual with dementia include [6]:

  • Anxiety
  • Suspiciousness
  • Nervousness
  • Anger
  • Irritability
  • Hostility
  • Confusion
  • Speaking inappropriately
  • Changed interests in hobbies, food, or other areas
  • Impulsive behaviors
  • Hallucinations
  • Delusions

Seizure conditions

Conditions that cause seizures, such as epilepsy, can cause significant changes in behavior and personality, such as [7]:

  • Suspiciousness
  • Delusions
  • Impulsive and disinhibited behaviors
  • Depression
  • Anxiety

Brain infections

Infections of the brain, such as HIV, encephalitis, and meningitis, can result in behavioral and personality changes, including [4][8]:

  • Aggression
  • Anger
  • Cognitive impairments
  • Impulsivity
  • Low mood
  • Anxiety  


Following a stroke, individuals may experience personality changes such as [9]:

  • Irritability
  • Disinhibited and impulsive behavior
  • Anhedonia
  • Depression
  • Anxiety

Physical health conditions that impact the body and cause personality changes can include:

Urinary tract infections

UTIs can cause changes in personality and behavior, particularly in older adults. This includes [10]:

  • Confusion and delirium
  • Agitation
  • Irritability

Thyroid conditions

Thyroid conditions, such as hyperthyroidism and hypothyroidism, can cause changes in personality, including [11]:

  • Depression
  • Anxiety
  • Agitation
  • Irritability

Liver failure

Liver disease can cause a condition in the brain called hepatic encephalopathy, which can cause personality changes such as [12]:

  • Confusion
  • Anxiety
  • Irritability
  • Lethargy

Kidney failure

Kidney disease can result in personality changes such as [4][13]:

  • Anger
  • Depression
  • Anxiety
  • Cognitive impairment

Low blood sugar (hypoglycemia)

Hypoglycemia can cause severe changes in personality and behavior, including [14]:

  • Confusion
  • Anxiety
  • Low mood
  • Irritability

Mental health conditions that can cause personality changes include:


Schizophrenia can cause changes in personality, including [15]:

  • Hallucinations
  • Delusions
  • Paranoia and suspiciousness
  • Bizarre or disorganized thoughts, speech, and behavior

Bipolar disorder

Bipolar disorder can cause episodes of mania and depression which may cause personality changes such as [16]:

  • Erratic or reckless behaviors
  • Grandiosity
  • Hyperactivity
  • Low mood
  • Social withdrawal
  • Anhedonia


Depression can cause personality and behavior changes such as [17]:

  • Persistent low mood
  • Reduced levels of interest in hobbies and activities
  • Impairments in daily functioning
  • Restlessness
  • Social withdrawal
  • Reduced energy levels and slowed speech and movement

Personality disorders

Personality disorders can cause several changes in personality, such as [18]:

  • Emotional lability
  • Outbursts of anger or aggression
  • Engaging in reckless or dangerous behavior
  • Odd or disorganized behaviors
  • Magical thinking
  • Grandiosity
  • A decline in self-esteem

Trauma and stress-related disorders

Some people may develop a trauma or stress-related disorder following a distressing event. This could cause changes in personality, such as [19]:

  • Suddenly becoming very anxious around people
  • Avoiding certain places
  • Experiencing frequent mood swings
  • Becoming very tense or restless

Anxiety disorders

Changes in personality that occur due to anxiety disorders may include [20]:

  • Avoiding social events
  • Becoming fearful of leaving the house
  • Developing a new fear of certain people, places, or objects
  • Feeling very nervous
  • Spending a lot of time worrying about things

Substances and medications that can cause changes in personality due to intoxication, withdrawal, or side effects, include [4]:

  • Alcohol
  • Amphetamines
  • Cocaine
  • LSD
  • Benzodiazepines
  • Opiates
  • Anticonvulsants
  • Antidepressants
  • Antipsychotics
  • Sedatives
  • Antihistamines

Physical symptoms to look out for

If physical symptoms emerge alongside personality changes, it may indicate the presence of a medical condition or emergency. Sudden onset of personality changes occurring alongside any of the following physical symptoms should be immediately reported to a doctor [4]:

  • Delirium
  • Fever
  • Severe headache
  • Recent head injury
  • Very high or irregular heart rate
  • Signs of brain damage, such as impaired vision, mobility, or speech

Diagnosing personality changes

When diagnosing personality changes, a doctor or other healthcare professional will initially aim to determine the cause, ascertaining whether it is related to a physical or mental health condition.

They will ask the individual for their medical history, family history of mental and physical health conditions, current diagnoses, and any medications or substances being taken or recently stopped [21].

Similarly, they will likely ask questions about the presenting symptoms, including any physical concerns, such as headaches, swelling, pain, palpitations, tingling, numbness, shaking, or mobility and speech impairments. They may test the individual’s brain function by examining speech, mobility, and vision [4].

A mental state examination (MSE) will often be conducted to gather information about mood, behavior, attention, memory, language, and speech.

The doctor will aim to determine the severity of the presenting symptoms, when they started, and if there have been any changes.

They will likely conduct blood tests to check for substance use and abnormalities that indicate physical health conditions, such as infection, electrolyte imbalances, and abnormal blood sugar levels. Additionally, the individual’s vital signs will be tested, such as blood pressure, temperature, and heart rate [4][21].

If there is no sign of infection, brain damage, or disease, it may be likely that a mental health condition has caused personality changes. If this is the case and there has been no prior mental health diagnosis, a referral may be required. A mental health professional can provide appropriate assessment, diagnosis, and treatment [22].

What are personality disorders?

Personality disorders are a group of conditions that can impact a person’s mood, behaviors, and interpersonal relationships. Sometimes, personality disorders emerge as a response to traumatic experiences, although genetic and environmental factors may also influence their development.

Changes that occur due to personality disorders often emerge in childhood and adolescence. Generally, these changes do not happen suddenly but will gradually develop and increase over several years [18].

The DSM-5 lists nine personality disorders in three groups [18][19].

Cluster A personality disorders tend to involve eccentric or odd behaviors and thoughts. This includes:

Cluster B personality disorders tend to involve dramatic or volatile behaviors, including mood swings, outbursts of anger, and grandiosity. This group of personality disorders is also often associated with unstable relationships and reckless or unsafe behaviors. Cluster B includes:

Cluster C personality disorders involve anxious and fearful behaviors, low self-esteem, and impaired social skills. This includes:

Treating personality changes

Treatment for personality changes will vary depending on the cause of symptoms. If personality changes have occurred due to a mental health condition, the individual will be offered therapy and medication to treat the condition [22].

Medications for various mental health conditions may include [15][16][17][18]:

  • Schizophrenia: Antipsychotics are often prescribed to treat schizophrenia symptoms. Antipsychotics can help reduce personality changes, including aggressive behaviors, social withdrawal, and hallucinations or delusions.
  • Depression: Antidepressants are often prescribed to treat depression symptoms. Antidepressants can help to reduce personality changes caused by depression, such as anhedonia, social withdrawal, and low mood.
  • Bipolar: Bipolar disorder is often treated with mood stabilizers, which can help to reduce extreme mood changes, thereby decreasing personality changes such as mania, impulsive behaviors, mood swings, and grandiosity.
  • Personality disorders: There are no FDA-approved medications for treating personality disorders, although various medications can be prescribed depending on the presenting symptoms. Antipsychotics, antidepressants, and mood stabilizers may be offered to help reduce personality changes caused by these conditions.

Various types of therapy are available to help manage and reduce personality changes and symptoms of these conditions. Therapeutic approaches, such as interpersonal therapy, cognitive behavioral therapy, and psychodynamic therapy, can reduce troubling personality changes by helping people with the following [22]:

  • Improving communication and social skills
  • Acknowledging and changing harmful thoughts and behaviors
  • Recognizing the impact of past events on current moods and behaviors
  • Increasing self-awareness
  • Learning how to cope with emotional distress

If personality changes have occurred due to a physical health condition, intervention will be immediately provided. This may involve medication or surgery. Treating the physical health condition can often alleviate or manage personality and behavior changes.

However, effectively treating the condition or reducing symptoms may not always be possible. In this case, it may be necessary to provide alternative treatments such as mental health medications and therapies to help the individual manage the impact of their physical, emotional, and behavioral symptoms [4][5][6][21].  

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Naomi Carr
Author Naomi Carr Writer

Naomi Carr is a writer with a background in English Literature from Oxford Brookes University.

Published: Sep 18th 2023, Last edited: Feb 21st 2024

Morgan Blair
Medical Reviewer Morgan Blair MA, LPCC

Morgan Blair is a licensed therapist, writer and medical reviewer, holding a master’s degree in clinical mental health counseling from Northwestern University.

Content reviewed by a medical professional. Last reviewed: Sep 18th 2023