Most people have heard about the more common types of dementia such as Alzheimer’s disease and vascular dementia. This page covers some of the rare types of dementia.
Some of the rare types of dementia include:
Frontotemporal dementia affects the frontal and temporal lobes of the brain, which play a significant role in decision-making, behavioural control, emotion and language.
Frontotemporal dementia often starts at a younger age than usually seen in other types of dementia (known as young-onset dementia), with an average of onset between 50 – 60 years of age.
Although for many people with frontotemporal dementia (FTD), the cause is not known, in around a third of people it can be triggered by a genetic problem known as ‘familial FTD’.
Frontotemporal dementia is caused when nerve cells in the frontal and/or temporal lobes of the brain die and the pathways that connect them change. There is also some loss of important chemical messengers. Over time, the brain tissue in the frontal and temporal lobes shrinks.
The main subtypes of FTD are called:
Behavioural variant FTD (bvFTD) – symptoms include changes in personality and social behaviour, and problems in reasoning and planning.
Two subtypes of Primary progressive aphasia or PPA known as:
Semantic dementia (SD) – symptoms include:
- Difficulty finding the right word – People may use another word instead of the correct one, for example saying ‘cat’ instead of ‘dog’, or calling something a ‘thing’ or another vague term.
- Losing understanding of what words mean – People may ask the meaning of a word that they have previously known.
- Talking about things in a vague manner – People may not seem to be making any sense when they speak.
- Difficulty understanding what other people are saying – Sometimes this can be put down to people seeming to be ‘deaf’.
- Problems with reading and spelling.
Progressive nonfluent aphasia (PNFA) – Aphasia is a condition that leads to problems using language correctly, including slow and hesitant speech, difficulty finding the right words to say, pronouncing words incorrectly or saying the opposite word to the one they mean.
A third subtype of PPA is also sometimes included called Logopenic aphasia (LPA). Patients with language problems usually show greater loss of brain tissue on the left side of the brain than on the right.
Parkinson’s disease dementia is caused by deposits of an abnormal protein (called Lewy bodies). Parkinson’s disease dementia is diagnosed when cognitive symptoms (i.e. dementia) develop more than a year after the onset of movement problems (i.e Parkinson’s disease). Parkinson’s disease dementia is one of the two types of Lewy body dementias.
Corticobasal degeneration (CBD) is a progressive neurological disorder characterised by nerve cell loss and atrophy (shrinkage) of multiple areas of the brain including the cerebral cortex and the basal ganglia.
Creutzfeldt-Jakob disease (CJD) is caused by an abnormally shaped protein called a prion infecting the brain. People affected by CJD usually die within six months of their early symptoms developing.
HIV-associated neurocognitive disorder (HAND) – HIV infection can cause a number of different problems in the brain, which affect up to half of people with HIV. Neurocognitive disorders in people with HIV may be caused by the virus directly damaging the brain. They may also be the result of a weakened immune system enabling infections and cancers to attack the brain.
Huntington’s disease (HD) is an inherited disease and is a progressive brain disorder that causes uncontrolled movements, emotional problems and problems with thinking (cognition). A persons mental abilities generally decline into dementia i.e. they become severe enough to affect daily life.
People are born with the defective gene, but symptoms usually don’t appear until middle age.
Wernicke-Korsakoff syndrome – Korsakoff syndrome is due to brain damage caused by a lack of vitamin B1 (thiamine). As Korsakoff syndrome often occurs as a result of alcoholism, it is sometimes referred to as alcoholic dementia.
In its early stages, the condition is known as Wernicke encephalopathy. Its symptoms can be reversed if people are given high doses of thiamine in time. If not, they often go on to develop Korsakoff’s syndrome.
Multiple sclerosis (MS) is a nervous system disease that affects your brain and spinal cord. Some people with MS experience a loss of some of their mental abilities. This happens if damage caused by the MS occurs in certain parts of the brain. The term ‘dementia’ is not generally used in association with multiple sclerosis because the decline is not usually as severe as it is in other forms of dementia. It is more usual to describe the person as ‘experiencing cognitive difficulties’.
Niemann-Pick disease is a group of diseases passed down through families (inherited) in which fatty substances called lipids collect in the cells of the spleen, liver, and brain.
Normal pressure hydrocephalus (NPH) is an abnormal buildup of cerebrospinal fluid (CSF) in the brain’s ventricles, or cavities. It occurs if the normal flow of CSF throughout the brain and spinal cord is blocked in some way. This causes the ventricles to enlarge, putting pressure on the brain.
Posterior cortical atrophy (PCA) also called Benson’s syndrome, is a form of dementia which is usually considered an atypical variant of Alzheimer’s disease. The disease causes atrophy of the back (posterior) part of the cerebral cortex, resulting in the progressive disruption of complex visual processing.
Progressive supranuclear palsy (PSP) is a rare and progressive condition that can cause problems with balance, movement, vision, speech and swallowing. It’s caused by increasing numbers of brain cells becoming damaged over time.