Types of dementia

Alzheimer's disease is the most common cause of dementia. It accounts for about 50-80% of dementia diagnoses.

People with Alzheimer’s tend to experience a gradual decline in their ability to remember, understand, communicate and reason. Some medications may be of use for some people to support the quality of day to day living in the early stages of the disease. However, these medications do not halt the disease process.

Vascular dementia, also called multi-infarct dementia, is the second most common form of dementia - occuring in twenty to thirty percent of cases. It is most commonly caused by multiple strokes and, occasionally, by a single stroke. Stroke occurs when blood flow in the brain is blocked by a blood clot in an artery or when an artery bursts and when this happens, brain cells are deprived of oxygen and die. People who have a large stroke will usually experience difficulties such as paralysis on one side of the body, speech and language problems or difficulties with coordination and movement. Some small strokes may just cause a 'funny turn' or not be noticed at all. However, each stroke is contributing to a build-up of damage to the brain, which can cause dementia.

Symptoms of vascular dementia are very similar to Alzheimer's disease. However, distinguishing features include neurological symptoms including weakness, clumsiness or altered sensation in the limbs or face.

Anyone can be affected by vascular dementia, but several factors increase the risk. These include:

  • High blood pressure
  • Smoking
  • Diabetes
  • High cholesterol
  • History of mild warning strokes
  • Evidence of disease in arteries elsewhere
  • Heart rhythm abnormalities.

Vascular dementia is slightly more common in men than women.

Some of the abilities lost in people with Alzheimer's disease may remain relatively unaffected in people with vascular dementia, since the condition affects the brain in a patchy fashion - symptoms can remain steady for a while and then suddenly decline. People with vascular dementia may also understand what is happening to them, more so than those with other forms of dementia, and this can make them prone to depression.

Vascular dementia is usually diagnosed through neurological examination and brain scanning techniques such as computerised tomography (CT) or a magnetic resonance imaging (MRI) test. Vascular dementia can be very difficult to distinguish from other forms of dementia and it is common to have both Alzheimer's disease and Vascular dementia. For more information about Vascular dementia, please visit this website.

Dementia with Lewy bodies (DLB) is also similar to Alzheimer's disease in that it is caused by the degeneration and death of nerve cells in the brain. Lewy bodies are tiny protein deposits found in nerve cells and their presence disrupts the brain's normal functioning, interrupting the action of important chemical messengers. Lewy bodies are also found in the brains of people with Parkinson's disease and researchers do not yet fully understand why Lewy bodies occur in the brain.

Symptoms of DLB include fluctuation, stiffness and trembling, a fluctuating ability to complete tasks from hour to hour, even from minute to minute as well as fainting, falling or unexplained turns and visual hallucinations. People with DLB experience memory loss, confusion regarding time and whereabouts, communication difficulties, slowness, muscle stiffness, trembling of the limbs, a tendency to shuffle when walking, loss of facial expression and changes in strength and tone of voice, all characteristic’s of Parkinson's disease.

DLB affects men more than women and is more prevalent in people over the age of 65.

An accurate diagnosis is important because people with DLB can react badly to neuroleptic drugs - strong tranquillisers which are often prescribed to people with dementia. There is currently no cure for DLB and while some people may benefit from anti-Parkinson's disease drugs, they may worsen hallucinations and confusion. For more information about Dementia with Lewy bodies, please visit this website.

Fronto-temporal dementia is the name given to dementia when there is degeneration in one or both of the frontal or temporal lobes of the brain. Including ‘Pick's disease’, it is a relatively rare type of dementia usually affecting people under the age of 65.

  • Frontal Lobes: the right and left frontal lobes govern mood, behaviour, judgement and self-control. Damage leads to alterations in personality and behaviour, changes in the way a person feels and expresses emotion and loss of judgement.
  • Temporal Lobes: the right and left temporal lobes are involved in the organisation of sensory input such as what you hear or see. Damage may lead to difficulty placing words or pictures into categories. There is considerable difference in FTLD symptoms depending on which parts of the frontal and temporal lobes are affected.

People with fronto-temporal dementia may:

  • Lack insight, lose the ability to empathise with others and appear selfish and unfeeling
  • Become extroverted when previously introverted or withdrawn when previously outgoing
  • Behave inappropriately - make tactless comments, joke at the wrong moment or act rudely
  • Have a loss of inhibitions - exhibit sexual behaviour in public
  • Become aggressive
  • Be easily distracted
  • Develop routines - compulsive rituals
  • Overeat and/or develop a liking for sweet food
  • Have difficulty finding the right words
  • Lack the ability to have spontaneous conversation
  • Use many words with little content
  • Experience a reduction in, or lack of, speech.

In the later stage of the disease, those affected may no longer recognise friends and family and may need nursing care. Fronto-temporal dementia is commonly misdiagnosed as Alzheimer's disease but a specialist may be able to make a diagnosis of fronto-temporal dementia by questioning the person affected and by taking a detailed history of their symptoms. Brain imaging scans may be also used to determine the extent of damage to the brain. Click here for more information on fronto-temporal dementia.

Other types of dementia include:

Dementia can also occur in people with Parkinson's diseaseHuntington's disease and Down Syndrome

Younger Onset Dementia describes any form of dementia diagnosed in people under the age of 65.

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