What Are Brain Diseases?


The brain is a crucial organ of the central nervous system (CNS), responsible for keeping us alive and allowing us to function.  Brain diseases, or neurological conditions, have become a global burden, causing 9 million deaths per year.1 As our life expectancy improves, this problem is only predicted to increase further.2 So what are brain diseases? This medical term describes any condition that causes brain damage and leads to impairments in functions like movement, memory, and thinking, depending on where the damage occurs in the brain.

There are several different types of brain diseases:

While these conditions are very different, there are some commonalities in terms of causes, symptoms, and treatment. This article will explore these, providing an overview of these neurological conditions.

Causes of brain diseases

Brain diseases are very complex and often have several causes. Usually, a mix of genetic, environmental, and cellular factors contribute to the onset of the disease and its associated brain damage,2 as outlined below.


Some brain diseases can be caused by mutations in our DNA. This means the genetic code has changed and can lead to changes that negatively affect brain function. These mutations can be inherited; however, they mostly occur spontaneously.3 For example, in some cases of Alzheimer’s disease, the disease is caused by a mutation in the APP gene, which causes an excessive build-up of the protein it codes for and leads to brain damage.3

Environmental Causes

Several environmental and lifestyle factors have been associated with the onset of brain diseases. For example, bacterial or viral infections, or environmental toxins can increase the susceptibility to brain diseases like Parkinson’s disease or Multiple Sclerosis (MS) by triggering your immune system.2,4 MS has also been linked to vitamin D deficiency or a lack of UVB exposure.4 Brain tumours, can be caused by exposure to high-ionising radiation.5

Protein Aggregation

Most neurological conditions are associated with a build-up of a specific type of protein in the brain.6 These are usually proteins that your body normally makes, but genetic or environmental factors cause them to be made in excess, leading to brain tissue damage. The proteins associated with different brain diseases are listed below.

Alzheimer’s DiseaseAmyloid-beta (plaques), Tau (neurofibrillary tangles)3
Parkinson’s DiseaseAlpha-synuclein (Lewy bodies)7

Immune Function

Another common factor is neuroinflammation.2 This refers to an inflammatory response of your immune system in the brain. This is a normal response that can help protect the brain against disease, but if it becomes chronic it can contribute to brain dysfunction and damage. One cause of this neuroinflammation can be protein aggregation.2

Some brain diseases, like multiple sclerosis, are classified as autoimmune diseases.10 This means they are caused by your immune system attacking your own body’s tissues. In this case, the genetic and environmental factors associated with MS cause an autoimmune response, and it is the immune system that causes the damage in your own brain.

Signs and symptoms of brain diseases

Neurological conditions have different symptoms depending on the brain area they affect. The most common signs and symptoms to look out for are listed below.


All types of dementia are associated with memory loss and forgetfulness, but each type also has specific symptoms you can look out for.11

Alzheimer’s Disease

  • Difficulty planning or organising11
  • Feeling confused in places or areas you are not familiar with11
  • Feeling anxious more often11

Vascular Dementia

  • Muscle weakness or short-term feelings of paralysis11
  • Trouble walking or moving11
  • Changes in mood, such as feelings of depression11

Frontotemporal Dementia

  • Change in personality11
  • Language issues, struggling to find the right word11
  • Reduced social awareness11

Mixed Dementia

Mixed dementia means there is a combination of the other types of dementia in the brain. So, it causes a mixture of the other symptoms.11

Parkinson’s Disease

Parkinson’s disease affects the ‘motor loop’ in the brain,7 which allows you to carry out voluntary movements like standing up from your chair.

  • Slowness in voluntary muscle movements7
  • Feeling like your muscles are rigid, especially in your arms and legs7
  • Involuntary muscle tremors7
  • Changes in your gait and/or posture7

Brain Tumours

Primary brain tumours are tumours that start in the brain (they haven’t spread from a cancer elsewhere in the body).12 They can grow anywhere in the brain but share general symptoms such as chronic headaches and seizures.5 If you only experience seizures, you could be suffering from epilepsy, another type of brain condition.13

Multiple Sclerosis

The autoimmune attack associated with multiple sclerosis targets the central nervous system leading to a decline in motor function and other key senses. Symptoms include:

  • Feeling tired14
  • Trouble moving and walking14
  • Impaired vision14
  • Muscle rigidness or spasms14
  • Trouble thinking or planning14

Progressive Supranuclear Palsy

Progressive supranuclear palsy can affect various parts of your brain, including those required for movement and coordination. Because of this, it is sometimes confused with Parkinson’s, but the motor symptoms are largely experienced in your central muscles such as your back and neck.15

  • Trouble balancing15
  • Muscle rigidness15
  • Trouble sleeping15
  • Impaired vision15

Amyotrophic Lateral Sclerosis

ALS is a motor neuron disease, meaning it affects the neurons used to control muscles and movements.8 Its symptoms are:

  • Rigid or weak muscles16
  • Trouble speaking (slurring words) 16
  • Trouble eating or drinking16
  • In later stages of the disease, you might experience trouble breathing16

Management and treatment for brain diseases

Brain diseases are generally incurable because the damage cannot be reversed. If you are diagnosed with a brain disease, treatment usually involves management of the symptoms to maintain your quality of life. These include:

  • Physiotherapy and drugs, such as levodopa, for symptoms affecting muscles7, 15
  • keeping socially and mentally active to manage diseases that affect cognition and memory, like dementia2
  • for brain tumours, a combination of surgery, radiotherapy, and chemotherapy5
  • A balanced and healthy diet to maintain brain health17


What are the types of brain diseases

Various types of brain diseases that each have a different pathology and symptoms depending on what part of the brain they affect. These include dementia, Parkinson’s disease, brain tumours, multiple sclerosis, epilepsy, Amyotrophic Lateral Sclerosis (ALS), Progressive Supranuclear Palsy (PSP), and prion disease.

How are brain diseases diagnosed

Most brain diseases are diagnosed through assessments of the symptoms experienced, family history, cognitive and physical tests, and x-rays.

How can I prevent brain diseases

While brain diseases are complex in their origins, and some of their causes are out of our control, there are some lifestyle factors that may help to maintain and support your brain health. These include eating a Mediterranean-style diet, physical exercise, not smoking, getting sufficient slee and remaining mentally and socially active.17

Who are at risks of brain diseases

In general, older adults (60 years and over) are at greater risk of developing brain diseases. Other factors that increase your risk include family history, cardiovascular and metabolic factors including hypertension and obesity, and smoking.4, 17  

How common is brain diseases

It is estimated that 1 in 6 people suffer from a brain disease, globally.18

When should I see a doctor

If you experience any of the signs or symptoms of a brain disease or are worried you might have one, you should visit your doctor as soon as possible.


​​Brain diseases cover a range of neurological conditions that impair brain function and can affect our everyday lives. They are caused by a combination of genetic and environmental factors that we can’t necessarily control. Depending on the brain region they affect, they cause different symptoms that can be managed to maintain your quality of life if they are diagnosed early enough.


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  2. Ludewig P, Gallizioli M, Urra X, Behr S, Brait VH, Gelderblom M, et al. Dendritic cells in brain diseases. Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease [Internet]. 2016 Mar [cited 2023 Mar 3];1862(3):352–67. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0925443915003336
  3. Schneider JA. Neuropathology of dementia disorders. CONTINUUM: Lifelong Learning in Neurology [Internet]. 2022 Jun [cited 2023 Mar 3];28(3):834–51. Available from: https://journals.lww.com/10.1212/CON.0000000000001137
  4. Dobson R, Giovannoni G. Multiple sclerosis – a review. Eur J Neurol [Internet]. 2019 Jan [cited 2023 Mar 3];26(1):27–40. Available from: https://onlinelibrary.wiley.com/doi/10.1111/ene.13819
  5. Perkins A, Liu G. Primary brain tumors in adults: diagnosis and treatment. Am Fam Physician. 2016 Feb 1;93(3):211–7.
  6. Zhu C, Aguzzi A. Prion protein and prion disease at a glance. Journal of Cell Science [Internet]. 2021 Sep 1 [cited 2023 Mar 3];134(17):jcs245605. Available from: https://journals.biologists.com/jcs/article/134/17/jcs245605/272014/Prion-protein-and-prion-disease-at-a-glance
  7. Kalia LV, Lang AE. Parkinson’s disease. The Lancet [Internet]. 2015 Aug [cited 2023 Mar 3];386(9996):896–912. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0140673614613933
  8. Mejzini R, Flynn LL, Pitout IL, Fletcher S, Wilton SD, Akkari PA. Als genetics, mechanisms, and therapeutics: where are we now? Front Neurosci [Internet]. 2019 Dec 6 [cited 2023 Mar 3];13:1310. Available from: https://www.frontiersin.org/article/10.3389/fnins.2019.01310/full
  9. Borroni B, Agosti C, Magnani E, Di Luca M, Padovani A. Genetic bases of progressive supranuclear palsy: the mapt tau disease. Curr Med Chem. 2011;18(17):2655–60.
  10. Cotsapas C, Mitrovic M, Hafler D. Multiple sclerosis. In: Handbook of Clinical Neurology [Internet]. Elsevier; 2018 [cited 2023 Mar 3]. p. 723–30. Available from: https://linkinghub.elsevier.com/retrieve/pii/B9780444640765000466
  11. Symptoms of dementia [Internet]. nhs.uk. 2017 [cited 2023 Mar 3]. Available from: https://www.nhs.uk/conditions/dementia/symptoms/
  12. Types of brain tumours [Internet]. [cited 2023 Mar 3]. Available from: https://www.cancerresearchuk.org/about-cancer/brain-tumours/types
  13. Thijs RD, Surges R, O’Brien TJ, Sander JW. Epilepsy in adults. The Lancet [Internet]. 2019 Feb [cited 2023 Mar 3];393(10172):689–701. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0140673618325960
  14. Multiple sclerosis [Internet]. nhs.uk. 2017 [cited 2023 Mar 3]. Available from: https://www.nhs.uk/conditions/multiple-sclerosis/
  15. Rowe JB, Holland N, Rittman T. Progressive supranuclear palsy: diagnosis and management. Pract Neurol. 2021 Oct;21(5):376–83.
  16. Amyotrophic lateral sclerosis(Als) [Internet]. National Institute of Neurological Disorders and Stroke. [cited 2023 Mar 3]. Available from: https://www.ninds.nih.gov/health-information/disorders/amyotrophic-lateral-sclerosis-als
  17. Dominguez LJ, Veronese N, Vernuccio L, Catanese G, Inzerillo F, Salemi G, et al. Nutrition, physical activity, and other lifestyle factors in the prevention of cognitive decline and dementia. Nutrients. 2021 Nov 15;13(11):4080.
  18. UK neuro facts [Internet]. [cited 2023 Mar 3]. Available from: https://www.brainresearchuk.org.uk/info/neuro-facts
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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