Rarer causes of dementia

Expert reviewer Rahul Bhattacharya, Consultant Psychiatrist
Next review due August 2022

Dementia is a term used to describe a set of symptoms. These can include problems with memory and thinking. There are four common causes or 'types' of dementia: Alzheimer's disease, vascular dementia, dementia with Lewy bodies, and frontotemporal dementia. But there are also a number of possible rarer causes of dementia symptoms. This page looks at some of these rarer causes of dementia in more detail.

Parkinson's disease

Around two to three out of every 10 people with Parkinson’s disease will develop some symptoms of dementia or slowing down mentally. This is more common when Parkinson’s is more advanced than in the early stages.

Parkinson’s dementia is similar to a type of dementia called dementia with Lewy bodies. The main difference is that, in Parkinson’s dementia, problems with physical movement usually start years before any problems with thinking and memory. Both conditions have protein deposits called Lewy bodies found in brain cells. These may be harmful to the brain cells and cause dementia, but doctors don’t know this 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, although it is less common than in dementia with Lewy bodies, and the hallucinations are less severe.

Other symptoms of dementia in Parkinson’s can include:

• slowed thinking, poor concentration and difficulty planning
• personality changes, such as loss of usual interests (apathy) and moodiness
• memory loss
• difficulty recognising people and making sense of surroundings (which can increase risk of falls)

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

If someone with Parkinson’s has symptoms of dementia, there are medicines that can help. They don’t help everyone, so your doctor may suggest trying them for a few months. In some people they can make tremor worse and cause sickness. There are three medicines that doctors will usually prescribe first, which are also used to treat Alzheimer’s disease:

• donepezil (Aricept)
• galantamine (Reminyl)
• rivastigmine (Exelon)

Normal pressure hydrocephalus (NPH)

Hydrocephalus is a condition where fluid builds up in the brain, causing increased pressure. Normal pressure hydrocephalus (NPH) has some of the same symptoms (eg difficulty walking), but the pressure in the brain isn’t actually significantly increased. In NPH, another sign is that some of the fluid-filled chambers in the brain (the ventricles) may appear enlarged on a scan.

Doctors aren’t quite sure what causes NPH. It may be to do with the reduced flow of blood leaving the brain, caused by blocked circulation (vascular disease). It may also be caused by problems with the circulation of fluid in the brain (cerebrospinal fluid). Sometimes a head injury or bleeding in the brain are thought to contribute to NPH developing.

Symptoms of dementia caused by NPH include:

• a general mental slowing down
• poor attention span
• loss of or reduced short-term memory

Memory problems may show up later than problems with thinking and managing.

As well as dementia, people with NPH develop difficulty walking. They may become slow and cautious, unsteady, or have difficulty changing direction. The doctor may try medicines for Parkinson’s disease but if these don’t help, it can help them to diagnose NPH. People with NPH may also develop loss of bladder control (urinary incontinence) later on in the disease.

If there is a build-up of fluid in the brain, NPH can be treated by putting in a tube to drain the excess fluid. This is called a shunt and drains the extra fluid into the abdomen. If someone can’t have surgery, the doctor may be able to drain off some fluid by doing a lumbar puncture (also called a spinal tap). This can work well, but the effects won’t last and it may have to be repeated.

The doctor may also suggest treatment to help stop any circulatory problems from getting worse, including stopping smoking, and medicines to reduce high blood pressure or cholesterol.

Multiple sclerosis

Multiple sclerosis is a condition where the insulation around nerve fibres is lost. This means the electrical signals that travel along the nerves are slowed down. There are different types of MS that develop at different rates. Memory problems and other dementia symptoms are most common if MS develops more rapidly.

As many as one in two people with MS will have some difficulties with thinking and remembering. This depends on the areas of the brain that the MS is affecting. It doesn’t mean that this many people with MS have dementia or need dementia treatment. In many people the effects will be slight. They may have:

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

Up to one in 10 people with MS will develop dementia. People with MS also have a tendency to depression. This should be treated with anti-depressants as it can make these other dementia-like symptoms worse.

Treatment will generally be aimed at managing symptoms. As well as anti-depressants, doctors may suggest short-term medicines to help control anxiety if this is a problem.

Progressive supranuclear palsy (PSP)

Progressive supranuclear palsy (PSP) is a rare condition that affects your movement. It gradually gets worse over a number of years. PSP commonly causes difficulties with thinking and memory, although these problems are generally less severe than they would be in dementia.

PSP affects the nervous system. It usually starts in middle age, with some symptoms similar to Parkinson’s disease, although any shaking or tremors are likely to be less strong. People may have difficulty moving the eyes to look up or down. They may also become unsteady with a tendency to have falls.

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.

Unfortunately, there is no cure for PSP and treatment aims to control symptoms. The doctor may suggest medicines to help with stiffness, or medicines called tricyclic anti-depressants. Physiotherapy and occupational therapy may help with movement and reduce the risk of falling.

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

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

Unfortunately, there is no cure for PSP and treatment aims to control symptoms. The doctor may suggest medicines to help with stiffness, or medicines called tricyclic anti-depressants. Physiotherapy and occupational therapy may help with movement and reduce the risk of falling.

Huntington's disease

Huntington's disease (HD) used to be called Huntington’s chorea. It is an inherited (genetic) condition that usually shows up in middle age. It affects the nervous system, causing characteristic jerky movements.

People with HD may have personality or behaviour changes as a first sign that they have the condition. This develops into the typical jerky movements. Over a number of years, people become less mobile and begin to develop dementia. Symptoms include:

• slowed thinking and poor concentration
• anxiety
• loss of interest in life (apathy)
• irritability and agitation
• developing obsessions or compulsive behaviour

As many as two out of three people with HD develop depression at some stage of their illness with HD. This may be more likely in the later stages of the disease. Unfortunately, there is no cure for HD and treatment aims to control symptoms. The doctor may suggest medicines for depression or anxiety. If agitation or compulsive behaviour is a particular problem, they may prescribe medicines called anti-psychotics.

Creutzfeldt–Jakob disease (CJD)

Creutzfeldt–Jakob disease (CJD) is a type of ‘prion disease’. This is a disease where a brain protein is folded wrongly, so that it doesn’t work properly.

CJD is very rare. Over 20 years, fewer than 1,500 people died of CJD in the UK. Most of these people developed a ‘sporadic’ type that just happens. There are different types which are even less common, including a type linked to eating meat from cattle infected with BSE (bovine spongiform encephalopathy, sometimes called ‘mad cow disease’). Only around one in 10 people who died over the 20 years developed this type.

CJD is a condition that gets worse over time and this can be very quick. One of the main features of CJD is memory loss and confusion. Other symptoms include:

• early signs of difficulty with organising, planning and multi-tasking
• loss of speech
• poor coordination and loss of control of body movements
• jerking muscle movements
• agitation and depression

Unfortunately, there is no cure for CJD. Treatment is aimed at managing symptoms and keeping people as comfortable as possible. Doctors may prescribe anti-depressants and medicines for anxiety and agitation. People with CJD may also have medicines for difficulty sleeping and to try to control muscle spasms.

Wilson’s disease

Wilson’s disease is a condition where the body doesn’t deal properly with copper from your diet. This copper builds up in the liver, brain and other organs, where it causes damage.

Wilson’s disease is a genetic condition that can be hard to spot. Sometimes it is picked up because of early signs, including greenish-gold rings around the iris (the coloured part of your eye), blood in the urine or in women, periods stopping or repeated miscarriage.

If Wilson’s disease isn’t diagnosed early, it may cause dementia-like symptoms, including changes in concentration and memory, behaviour and mood, and problems with coordination. As well as these, someone may have:

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

Wilson’s disease tends to be diagnosed earlier in life, between the ages of five and 40. However, in theory, it can develop at any age.

Wilson’s disease is treatable. This is done with medicines called ‘chelating agents’. These remove copper from the body. The doctor may also prescribe zinc, as this stops your body from absorbing any more copper but it won’t get rid of the excess. Once you’ve been diagnosed, you have to take these medicines for life, to prevent high levels of copper from collecting.

Some symptoms that have developed before treatment starts may remain permanently, but others will improve. If Wilson’s disease isn’t treated, it is usually fatal.

Wilson’s disease tends to occur earlier in life, between the ages of five and 35. However, in theory, it can develop at any age.

Wilson’s disease is treatable. This is done by removing toxic levels of copper from the body, and stopping it from reappearing, usually with medicines. However, some symptoms that have developed before treatment starts may remain permanently. If Wilson’s disease isn’t treated, it is often fatal.