Rarer causes and types of dementia

Your health experts: Dr Pravir Sharma, Consultant in Mental Health and Old Age Psychiatry and Dr Adrian Raby, General Practitioner
Content editor review by Rachael Mayfield-Blake, December 2021
Next review due December 2024

Dementia describes a set of symptoms, including problems with memory and thinking. There are four common types: Alzheimer's disease, vascular dementia, dementia with Lewy bodies, and frontotemporal dementia. But other conditions can cause rarer forms of dementia.

Parkinson's disease

Two or three out of every 10 people with Parkinson’s disease will develop dementia symptoms, or slow down mentally. This is more common when Parkinson’s is more advanced.

Parkinson’s dementia is similar to dementia with Lewy bodies. But in Parkinson’s, problems with physical movement usually start years before any problems with thinking and memory. In both conditions, protein deposits called Lewy bodies are found in brain cells. These may be harmful to the brain cells and cause dementia, but doctors don’t know for sure.

A typical symptom of dementia with Lewy bodies is seeing things that aren’t there (hallucinations). This also happens in Parkinson’s dementia, but it’s less common and hallucinations are less severe.

Other symptoms of dementia in Parkinson’s can include:

  • slowed thinking, poor concentration and difficulty planning
  • feeling sleepy during the day
  • personality changes, such as loss of usual interests (apathy) and agitated
  • memory loss
  • difficulty making sense of surroundings, increasing risk of falls

As well as dementia, many people with Parkinson's disease develop depression.

Medicines can help with Parkinson’s dementia symptoms. For mild-to-moderate dementia, you may have an acetylcholinesterase inhibitor, such as rivastigmine (eg Exelon). If this doesn’t help, you may have memantine hydrochloride (eg Ebixa).

Normal pressure hydrocephalus (NPH)

Hydrocephalus is a condition where fluid builds up in the brain, which increases pressure. Normal pressure hydrocephalus (NPH) has similar symptoms, such as difficulty walking, but the pressure in the brain isn’t significantly high.

Doctors aren’t sure what causes NPH. It may be reduced flow of blood leaving the brain, because of poor circulation due to vascular disease. Or it may be problems with the circulation of cerebrospinal fluid in the brain. A head injury or bleeding in the brain may help to cause NPH.

Dementia symptoms in NPH include::

  • general mental slowing down
  • poor attention span
  • poor short-term memory

Memory problems may show up later than problems with thinking and managing. People may also have difficulty walking, becoming slow and cautious, unsteady, or having difficulty changing direction. They may lose bladder control (urinary incontinence) later on in the disease.

Doctors may try medicines for Parkinson’s disease. If these don’t work, it can help them to rule out Parkinson’s and diagnose NPH.

You may have a lumbar puncture (spinal tap) to drain fluid from the brain. If this helps, the doctor may put in a tube (called a shunt) to drain excess fluid. This carries it to another part of the body, usually the tummy (abdomen), where it’s absorbed into the blood.

Treatment for preventing circulatory problems from getting worse can also help, including stopping smoking, and medicines for high blood pressure or cholesterol.

Multiple sclerosis

In multiple sclerosis (MS) the insulation around nerve fibres is lost. So the electrical signals travelling along nerves slow down. Different types of MS develop at different rates. Memory problems and other dementia symptoms are most common in rapidly developing MS.

Around half of people with MS will have difficulties with thinking and remembering at some stage of their illness.This can be slight in some people. They may have:

  • memory problems
  • difficulty learning new information
  • difficulty planning
  • poor concentration

Up to one in 10 people develop dementia. People with MS are also more likely to have depression. This should be treated with antidepressants as it can make dementia symptoms worse.

Treatment is generally aimed at managing symptoms. Doctors may suggest short-term medicines to help control anxiety.

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Progressive supranuclear palsy (PSP)

Progressive supranuclear palsy (PSP) is a rare condition that affects the nervous system and movement and can cause difficulties with thinking and memory. It usually starts in late middle age and gradually worsens over a number of years. .

Some symptoms are similar to Parkinson’s disease. People may have difficulty moving their eyes up and down. They may also become unsteady and tend to fall..

Symptoms can include:

  • memory problems
  • slowed thinking
  • personality changes, such as becoming more emotional

There are also physical symptoms. Muscles become rigid and movements are slowed.

There’s no cure for PSP – treatment aims to control symptoms. Medicines may reduce muscle stiffness. Physiotherapy and occupational therapy may help with movement and reduce risk of falls.

Huntington’s disease

Huntington's disease (HD) is an inherited (genetic) condition that usually starts when people are in their 30s and 40s. It affects the nervous system. The first signs of HD are personality or behaviour changes and jerky movements. Over several years, people become less mobile and develop severe dementia. Symptoms include:

  • slowed thinking and poor concentration
  • anxiety
  • depression
  • loss of interest (apathy)
  • aggression
  • irritability and agitation
  • obsessions or compulsive behaviour (later in the illness)

There’s no cure for HD – treatment aims to control symptoms. Doctors may prescribe medicines for depression or anxiety and anti-psychotics for agitation or compulsive behaviour.

Families can have genetic testing for Huntington’s disease. It can be difficult to decide whether to have this. It’s entirely your choice and you can take as long as you need. You have the tests at a genetic clinic with counsellors available. You can talk to them about the testing and ask any questions you have before deciding.

Creutzfeldt–Jakob disease (CJD)

Creutzfeldt–Jakob disease (CJD) is a type of prion disease. Brain proteins (prions) become abnormal and fold wrongly, so they don’t work properly.

CJD is very rare. Between 1985 and 2020 in the UK, 2,494 people were diagnosed with the most common type (sporadic CJD). Other types are even rarer, including a type linked to meat from BSE infected cattle (bovine spongiform encephalopathy, or ‘mad cow disease’).

CJD worsens over time and this can be very quick. Main features are memory loss and confusion. Other symptoms include:

  • difficulty organising, planning and multi-tasking
  • double vision or hallucinations
  • poor coordination and loss of control of movement
  • jerking muscles
  • agitation and depression

There’s no cure for CJD. Treatment aims to manage symptoms and keep people as comfortable as possible. Doctors may prescribe .

  • anti-depressants
  • medicines for anxiety and agitation.
  • medicines for difficulty sleeping
  • medicines to control muscle spasms.

Wilson’s disease

In Wilson’s disease, the body can’t cope with copper in the diet. Copper builds up and damages the liver, brain and other organs.

Wilson’s disease is a genetic condition that can be hard to spot. It’s usually diagnosed between the ages of 10 and 40 but can develop at any age.

Early signs include greenish-brown rings around the iris (the coloured part of your eye), blood in the urine, periods stopping or repeated miscarriages. But only between five and 10 people in 100 (5-10%) have these early signs.

Wilson’s disease that isn’t diagnosed early may cause dementia symptoms, including difficulty focusing on tasks, memory loss, behaviour and mood changes, and problems coordinating. People may also have:

  • liver problems such as hepatitis and cirrhosis
  • slow or slurred speech
  • tremor
  • muscle spasms and twitches
  • excessive saliva (drooling)

It can be treated with medicines called chelating agents, which remove copper from the body. Doctors may also prescribe zinc. This stops the body from absorbing more copper but doesn’t get rid of the excess. You take these medicines for life, to prevent high levels of copper collecting.

Symptoms that develop before treatment starts may be permanent, but others will improve. If Wilson’s disease isn’t treated, it’s usually fatal.

Seven in 10 people with dementia have Alzheimer’s disease - the most common type. It affects around 850,000 people in the UK. Early symptoms include memory problems, and behaviour changes, increased irritability, for example.

See our topic on Alzheimer’s disease for more information.

There are many rare types of dementia including progressive supranuclear palsy (PSP), Creutzfeldt–Jakob disease (CJD) and Wilson’s disease. In the UK, about one in 20 people who have dementia have a rarer type..

See the information above on rarer causes of dementia.

Dementia usually develops over time and gets steadily worse. How quickly symptoms develop depends on the type of dementia. For example Creutzfeldt–Jakob disease (CJD), can get worse very quickly..

See our section: Creutzfeldt–Jakob disease (CJD) above for more information.

Around two in 10 people with early-onset dementia have this type. Personality changes and problems with speaking and language usually come on before memory problems.

See our topic on frontotemporal dementia for more information.

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  • Neuropsychiatry. Oxford Handbook of Psychiatry. Oxford Medicine Online., published online June 2019
  • Dementia. NICE Clinical Knowledge Summaries., last revised May 2021
  • Parkinson's disease. NICE Clinical Knowledge Summaries., last revised February 2018
  • Dementia with Lewy bodies and Parkinson disease dementia. MSD Manuals., last full review/revision March 2021
  • Dementia. Parkinson's UK., last updated October 2019
  • Parkinson's disease. NICE Clinical Knowledge Summaries., last revised February 2018
  • Parkinson's disease. NICE British National Formulary., last updated 6 October 2021
  • Rivastigmine. NICE British National Formulary., last updated 6 October 2021
  • Memantine hydrochloride. NICE British National Formulary., last updated 6 October 2021
  • Meng Y-H, Wang P-P, Song Y-X, et al. Cholinesterase inhibitors and memantine for Parkinson's disease dementia and Lewy body dementia: a meta-analysis. Exp Ther Med 2019; 17(3):1611–24. doi:10.3892/etm.2018.7129
  • Normal pressure hydrocephalus. BMJ Best Practice., last reviewed 28 September 2021
  • Normal-pressure hydrocephalus. MSD Manuals., last full review/revision March 2021
  • Normal pressure hydrocephalus. Alzheimer's Association., accessed 28 October 2021
  • Multiple sclerosis. NICE Clinical Knowledge Summaries., last revised August 2020
  • Multiple sclerosis. BMJ Best Practice., last reviewed 28 September 2021
  • Multiple sclerosis. Patient., last edited 23 March 2020
  • Other diseases causing dementia. Practical dementia care. Oxford Medicine Online., published online May 2016
  • Progressive supranuclear palsy (PSP). MSD Manuals., last full review/revision May 2020
  • Progressive supranuclear palsy. Patient., last edited 24 January 2019
  • Huntington's disease. BMJ Best Practice., last reviewed 28 September 2021
  • Huntington disease. MSD Manuals., last full review/revision May 2020
  • Overview of prion diseases. MSD Manuals., last full review/revision July 2020
  • 29th annual report 2020 Creutzfeldt-Jakob disease surveillance in the UK. The National CJD Research & Surveillance Unit., published 2020
  • Creutzfeldt-Jakob disease. Alzheimer's Association., accessed 29 October 2021
  • Prion disease. BMJ Best Practice., last reviewed 29 September 2021
  • Wilson's disease. BMJ Best Practice., last reviewed 29 September 2021
  • Wilson disease. MSD Manuals., last full review/revision May 2020
  • Wilson's disease. Patient., last edited 21 July 2021
  • Rarer types of dementia. Alzheimer's Society., accessed 29 October 2021
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