Brain Diseases

There are many types of brain diseases, ranging from injuries and infections to brain tumors and dementia. They can impact your ability to function and carry out daily activities. Outcomes vary widely depending on the type of brain disease, location and severity of the condition.


What are brain diseases?

Your brain is the control center of your body. It regulates growth, development and bodily functions. All of your thoughts, feelings and actions begin there.

Your brain is part of your nervous system. A network of nerves carries signals to your spinal cord and brain from your body and the outside world. Your brain processes the signals and sends responses back out through your spinal cord and nerves.

A wide range of diseases and disorders affect your brain. They can alter a person’s behavior, personality and their ability to process information and function. Many brain diseases impact a person’s capacity to carry out daily activities.


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What are the types of brain diseases?

There are many types, including hundreds, of rare brain diseases. The general categories of brain diseases include:

Autoimmune brain diseases

Autoimmune brain diseases occur when your body’s defenses attack a part of your brain, mistaking it for an invader. Multiple sclerosis (MS) is the most prominent of these. Like electrical wires, nerve cells have insulation covering them. Multiple sclerosis attacks this in your brain, spinal cord and the nerves going to your eyes. There are less common autoimmune brain diseases that mimic MS. There are others, like autoimmune encephalitis, which irritate your brain, causing confusion and involuntary movements.


Epilepsy is a tendency to have seizures. A seizure is an electrical storm in your brain, typically interfering with consciousness and causing convulsions (uncontrolled movements). Some seizures can be subtle — only causing clouding of consciousness or uncontrolled movements of one part of your body.


Infections occur when various types of germs invade your brain or its protective coverings. Meningitis happens when your protective coverings are infected. It often causes headaches, confusion and a very stiff neck. Sometimes, it’s necessary to do a spinal tap to find out which germ is causing an infection so the right antibiotics can be given.

Mental illness

Mental, behavioral and emotional disorders can diminish a person’s quality of life and ability to function. Major types include:

Psychiatrists and psychologists generally treat mental illnesses. If your brain were a computer (and in some ways, it is), your mind would be like a program running in it. In other words, your mind is your brain’s “operating system.” Psychiatrists and psychologists are like computer programmers who try to figure out why this program is causing distress instead of working as it should.

Often, treatment involves both medications and therapy. People are sometimes hesitant to see a mental health specialist. But they shouldn’t be. Mental illness affects 1 in 5 adults.

Neurodegenerative brain diseases

Neurodegenerative disorders are often due to the accumulation of abnormal proteins in your brain. They include Alzheimer’s disease, Parkinson’s disease and ALS (amyotrophic lateral sclerosis), among many others. They’re most often slowly progressive and interfere with thought, memory, movement or some combination of these things. They’re more common in the elderly. Some run in families.

Neurodevelopmental disorders

Neurodevelopmental disorders affect the growth and development of your brain, and are usually cared for by pediatric neurologists. Medical geneticists may determine whether a disorder is likely to be inherited. If it is, they provide family counseling. There are a large number of neurodevelopmental disorders, including:


Strokes occur when a blood vessel supplying your brain with the nutrients it needs gets blocked or, less often, bursts. Either way, the effects are sudden. Stroke damages part of your brain. This can lead to problems with speech, understanding, vision, strength, sensation or coordination. If enough of your brain is damaged by one or more strokes, it can cause dementia. Occasionally, seizures occur due to strokes.

Traumatic brain injuries

Traumatic brain injuries include concussions and more serious brain injuries such as gunshot wounds. Brain injury may happen due to falls, auto accidents, sports injuries or domestic violence (including child abuse). Repeated head trauma can cause brain scarring, leading to chronic traumatic encephalopathy (CTE). Neurosurgeons may care for penetrating injuries and bleeding. Psychologists, psychiatrists and speech therapists may be consulted for behavioral and thinking problems after brain injuries. Neurologists often care for the injured as well.


Brain tumors can develop when cancer spreads from other parts of your body, such as your lung, breast or colon. Or they can form in your brain tissue itself or its coverings.

Unlike tumors spreading from other places in your body, tumors arising in your brain itself or brain coverings are considered benign if they grow slowly and don’t invade surrounding brain tissue. They’re considered malignant if they grow rapidly and invade surrounding brain tissue.

Astrocytoma is a common tumor arising from your brain itself. Meningioma is a common tumor arising from the coverings of your brain.

How common are brain diseases?

Brain diseases affect many people, but the occurrence of individual diseases varies widely. For example, in the U.S.:

  • Alzheimer’s disease affects more than 6 million people.
  • Autism spectrum disorder occurs in about 1 in 44 children.
  • Brain tumors and other nervous system cancers are relatively rare, accounting for 1.3% of all cancers.
  • Epilepsy impacts 1.2% of the population, including 3 million adults and 470,000 children.
  • Meningitis is rare due to widespread use of the meningitis vaccine. In 2019, only 371 cases were reported.
  • Mental illness is very common, affecting 1 in 5 adults.
  • Multiple sclerosis is a condition nearly 1 million people are living with.
  • Strokes occur in nearly 800,000 people each year.
  • Traumatic brain injuries caused over 220,000 hospitalizations in 2018.

Symptoms and Causes

What causes brain diseases?

Some common causes and risk factors of brain disease are:

  • Environmental toxins and radiation: Long-term exposure to toxic chemicals and radiation may increase the risk of some brain diseases, such as brain tumors.
  • Genetics: Certain genes and genetic mutations can cause or increase the risk of many brain diseases. Researchers have identified genes or specific mutations involved in brain tumors, epilepsy, neurodegenerative disorders, neurodevelopmental disorders and mental illnesses. Disease-causing genes may run in families or occur spontaneously.
  • Immune system function: Autoimmune brain diseases happen when your immune system attacks other cells in your body.
  • Infections: Bacteria, viruses and other organisms cause brain diseases such as meningitis.
  • Injuries: Accidents and injuries cause most traumatic brain injuries. An injury to your brain can also increase your risk for other brain diseases, such as epilepsy and Alzheimer’s disease.
  • Unhealthy lifestyle choices: Poor diet, lack of exercise, smoking and alcohol use are linked to stroke and Alzheimer’s disease.

Healthcare providers aren’t sure why some types of brain diseases happen. For example, about 60% of epilepsy cases have no known cause (idiopathic). Researchers are actively investigating diseases of the brain to better understand their causes and how to treat them.

What are the symptoms of brain disease?

Your brain controls all of your bodily functions. If your brain is injured or diseased, any of those functions can be impacted depending on the type, location and severity of the condition. You may experience general symptoms, such as:

Brain diseases may also show up as changes in:

  • Balance.
  • Behavior.
  • Breathing.
  • Coordination.
  • Focus.
  • Memory.
  • Mood.
  • Movement.
  • Personality.
  • Physical sensations.
  • Speech.
  • Strength.
  • Swallowing.
  • Vision.

When in doubt, contact your healthcare provider.


Diagnosis and Tests

How are brain diseases diagnosed?

The most important step in diagnosis is the history and physical exam. During the physical exam, the emphasis is on the neurologic exam. It includes motor, sensory, reflex and thinking tests. The findings of this examination direct what other tests may be needed.

Other testing may include:

  • Biopsy: Your healthcare provider collects a small sample of tissue for laboratory analysis. Biopsies help determine whether a brain tumor is cancerous or noncancerous.
  • Diagnostic testing: These can include an electroencephalogram (EEG) to measure your brain’s electrical activity. Evoked potentials testing assesses the transmission of nerve signals to your brain.
  • Imaging tests: CT, MRI and PET scans provide detailed images of your brain. They can detect brain activity and areas of disease or damage.
  • Laboratory tests: Blood, urine, stool or spinal fluid testing can help your healthcare provider understand what might be causing your symptoms. Genetic testing can identify gene mutations known to cause some brain diseases.
  • Mental function tests: You complete these tests on paper or on a computer. These allow your healthcare provider to evaluate your memory, thinking and problem-solving abilities.
  • Neurological exam: Your healthcare provider will check for changes in your balance, coordination, hearing, eye movement, speech and reflexes.

Management and Treatment

How are brain diseases treated?

Beyond prevention, treatment varies with the kind of disorder. Some disorders can be cured (for example, taking an antibiotic for meningitis or removing a tumor). Others can be treated, but not cured (such as taking medications to control the symptoms of Parkinson’s disease or to prevent seizures). Others must be accommodated to (such as using a cane or walker to cope with some balance disorders).

Treatments your healthcare provider may use include:

  • Counseling and cognitive behavior therapy to manage mental health concerns and provide emotional support.
  • Diet, exercise and stress management to improve symptoms of some conditions such as Alzheimer’s and multiple sclerosis, and prevent recurrence of stroke.
  • Medications to treat the disease and manage symptoms.
  • Minimally invasive endovascular surgery to repair a burst blood vessel.
  • Physical, occupational or speech therapy to regain lost abilities.
  • Rest to help your brain heal.
  • Surgery to stop internal bleeding, remove a brain tumor or prevent epileptic seizures.


How can I prevent brain diseases?

“An ounce of prevention is worth a pound of cure.” A healthy diet and activity, along with controlling medical illnesses (such as high blood pressure, diabetes, and high cholesterol), and making sure you’re vaccinated against infections of the brain and nervous system can avoid preventable brain illness.

Here are some general guidelines that may reduce your risk for preventable brain diseases:

  • Adopting a healthy lifestyle. This includes a heart-healthy diet, regular exercise, quitting smoking, limiting alcohol consumption and reducing stress.
  • Avoiding excessive exposure to X-rays and other sources of radiation.
  • Ensuring you and your loved ones are vaccinated against bacterial meningitis.
  • Knowing the warning signs of a stroke and seeking immediate emergency medical care.
  • Managing chronic health conditions, such as high blood pressure, high cholesterol, diabetes and obesity.
  • Reducing your risk of head trauma by preventing falls, wearing your seatbelt and wearing a helmet when cycling or playing contact sports.
  • Staying mentally and socially active.

Outlook / Prognosis

What is the prognosis for people with brain disease?

Some brain diseases will heal without permanent damage. Others may resolve but leave deficiencies in your mental or physical abilities. Some are lifelong, progressive conditions. Your healthcare provider will work with you to manage your symptoms and help you preserve or regain as much function as possible.

Living With

When should I contact my healthcare provider?

Early treatment for brain injuries and diseases is essential. Have your healthcare provider check out any head injuries, even minor ones. Also, notify your healthcare provider if you experience any unusual changes in your:

  • Behavior, mood or personality.
  • Memory and ability to focus.
  • Physical function, including movement, balance and coordination.
  • Speech.
  • Vision.

Call 911 if you have any warning signs of a stroke. These are usually painless and cause sudden changes such as:

  • Altered speech (slurring or confusion) or difficulty understanding others.
  • Difficulty seeing in one or both eyes.
  • Headache.
  • Loss of balance, coordination or ability to walk.
  • Weakness or numbness in your face, arm or leg, especially on one side.

A note from Cleveland Clinic

There are many types of brain diseases. Some are quite common, while others occur in only a few hundred people each year. Your healthcare provider will evaluate you closely to determine what’s causing your symptoms and provide an individualized treatment plan. If you or a family member have experienced a brain injury or disease, follow your healthcare provider’s instructions for treatment and long-term management. Therapy, medications, lifestyle changes and proper support can help you live the fullest life possible.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 04/26/2022.

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