9 Health Conditions That Can Change Your Personality

Personality is the combination of characteristics or qualities that form a person’s distinctive character. Your habits, reactions, mannerisms, and thinking are all part of your personality. But some health conditions can affect the way you think and behave, which can collectively change your personality.

For instance, even if you’re down with a simple cold or flu, your behavior changes noticeably. However, most of the ailments that have a huge impact in altering your personality are mental health conditions. Here are a few health conditions that can affect your personality.


1. Depression

Depression affects your mood, thoughts, and memory

Depression has become a common mental health disorder that is affecting millions of people globally. From the youth to the elderly, it affects people of all ages. Most chronic mood disorders, such as depression, begin as high levels of anxiety in children.1


Depression not only affects your mood, but also your thoughts, your memory, and how you make decisions. It changes your perspective of the world and makes you feel that life is not worth living. Depression causes mood changes that can be very different in men and women. Women often feel worthless, sad, and guilty, while men tend to feel tired, irritated, and angry.

2. Thyroid Disease

Thyroid diseases can make you irritable, anxious and cause mood swings


The thyroid gland produces hormones, which are necessary for all the cells in your body to work normally. Overproduction of these hormones can make you irritable, anxious, and cause major mood swings. Underproduction of these hormones by the thyroid gland makes your personality seem flat.

You may become forgetful and have difficulty in thinking clearly. If left untreated, it can cause long-lasting or permanent effects on your brain. While patients with hypothyroidism commonly manifest features of depression, hyperthyroidism presents with a wider spectrum of neuropsychiatric symptoms including both depression and anxiety.2


3. Alzheimer’s Disease

Alzheimer’s disease affects your thinking, judgment, and memory

Alzheimer’s disease affects your thinking, judgment, memory, and decision-making capability. You may feel confused and not know how to act. In its initial stages, you may be anxious or more easily annoyed. Over time, it may have more serious health implications.


Depression and anxiety are common, especially during the initial stages when patients might have insight and are aware of their memory deficits.3 A friendly and easily adjusting person may become bossy and demanding. People who would worry or get stressed unnecessarily may suddenly become easygoing and content.

4. Dementia With Lewy Bodies

Dementia with Lewy bodies affects memory, movement, and thinking


This is the second most common type of dementia after Alzheimer’s. Clumps of unusual proteins known as Lewy bodies form in the areas of your brain that control memory, movement, and thinking.4 So, this disorder affects you both mentally and physically. People with this condition may become more passive.

This disorder only worsens over time and those who suffer from it may show little emotion and may lose interest in hobbies and other activities. Other symptoms may include fluctuations in alertness, hallucinations, slow movement, trouble walking, and rigidity.


5. Parkinson’s Disease

Parkinson’s disease can have an impact on how you walk, talk, sleep, and think

Parkinson’s disease is associated with motor fluctuations where many patients also develop mood fluctuations.5 Though it begins as mild shakiness in your hand, Parkinson’s can eventually affect how you walk, talk, sleep, and think.

Initially, it may cause the person to do things like obsessing over small details or a sudden carelessness. Later, they may seem absent-minded or not as social as they once were. It is also harder to keep their thoughts focused.

6. Brain Tumor

Brain tumor causes confusion and forgetfulness

A tumor in your brain’s frontal lobe can adversely affect the areas that are associated with your personality, emotions, problem-solving, and memory. When these areas of the brain are affected by tumor, you may feel confused or forgetful. It may also result in mood swings, make you more aggressive, or trigger paranoid thoughts. Various factors can cause changes in behavior in patients with brain tumors.

The location, size, and rate of growth of the tumor can impact how a patient behaves. Even treatments such as radiation, surgery, and chemotherapy can affect how the patient feels and behaves. The psychological and emotional effects of brain tumors also must be considered.6 Even certain types of cancer can change a person’s behavior. Tumors in the brain or the spinal cord or even the pituitary gland, which controls your hormone levels, can affect personality.

7. Stroke

eople who suffer from a stroke may experience mood swings

When blood supply to a part of your brain stops, the cells in that area are deprived of oxygen and begin dying. The effects also depend on how long the stroke lasts and where in the brain it occurs. Some parts of your body may become immobile, which can alter your personality in many ways.

You may become impatient more easily, experience serious mood swings, or act more impulsively than you did before. Mood and emotional disturbances are frequent symptoms in stroke survivors. These symptoms are distressing for both the patients and their caregivers, and negatively influence your quality of life.7

8. Traumatic Brain Injury

Traumatic brain injuries can make you feel like a different person altogether

A serious blow to the head can change the personality of a person. In extreme cases, you may feel that you’re a different person and say or do things that you would never have in the past. Disorders of mood are common consequences of traumatic brain injury (TBI).8

Certain parts of the brain such as the hippocampus are more vulnerable to damage from injuries. Disruption in hippocampal functioning and morphology has been described in cognitive and depressive disorders.9

9. Obsessive-Compulsive Disorder

OCD can affect your mood and criticism worsens the condition

Obsessive-compulsive disorder (OCD) makes you anxious and prevents you from controlling your thoughts and urges. People with OCD may repeatedly wash their hands even if they’re clean. They are prone to self-doubt and may take a long time to complete easy tasks.

Criticism worsens the condition as it only increases your anxiety. OCD is considered an anxiety disorder that may also occur along with other neuropsychiatric disorders and especially with other anxiety and mood disorders.10