What is Dementia?
Dementia describes a collection of symptoms that are caused by disorders affecting the brain. It is not one specific disease. Dementia affects thinking, behavior and the ability to perform everyday tasks. Brain function is affected enough to interfere with the person's normal social or working life. The hallmark of dementia is the inability to carry out everyday activities as a consequence of diminished cognitive ability. Doctors diagnose dementia if two or more cognitive functions are significantly impaired. The cognitive functions affected can include memory, language skills, understanding information, spatial skills, judgement and attention. People with dementia may have difficulty solving problems and controlling their emotions. They may also experience personality changes. The exact symptoms experienced by a person with dementia depend on the areas of the brain that are damaged by the disease causing the dementia. The condition is usually progressive; the disease gradually spreads through the brain and the person's symptoms get worse over time.
Who gets dementia?
Dementia can happen to anybody, but the risk increases with age. Most people with dementia are older, but it is important to remember that most older people do not get dementia. It is not a normal part of ageing, but is caused by brain disease. Less commonly, people under the age of 65 years develop dementia and this is called 'younger onset dementia'. There are a few very rare forms of inherited dementia, where a specific gene mutation is known to cause the disease. In most cases of dementia however, these genes are not involved, but people with a family history of dementia do have an increased risk.
Certain health and lifestyle factors also appear to play a role in a person's risk of dementia. People with untreated vascular risk factors including high blood pressure, cholesterol and diabetes have an increased risk, as do those who are less physically and mentally active.
What causes dementia?
There are many different diseases that cause dementia. In many cases, why people develop these diseases is unknown. Some of the most common forms of dementia are:
Alzheimer's disease is the most common form of dementia, accounting for around two-thirds of cases. It causes a gradual decline in cognitive abilities, often beginning with memory loss. Alzheimer's disease is characterised by two abnormalities in the brain – amyloid plaques and
neurofibrillary tangles. The plaques are abnormal clumps of a protein called beta amyloid. The tangles are bundles of twisted filaments made up of a protein called tau. Plaques and tangles stop communication between nerve cells and cause them to die.
Vascular dementia is cognitive impairment caused by damage to the blood vessels in the brain. It can be caused by a single stroke, or by several strokes occurring over time.Vascular dementia is diagnosed when there is evidence of blood vessel disease in the brain and impaired cognitive function that interferes with daily living. The symptoms of vascular dementia can begin suddenly after a stroke, or may begin gradually as blood vessel disease worsens. The symptoms vary depending on the location and size of brain damage.It may affect just one or a few specific cognitive functions. Vascular dementia may appear similar to Alzheimer's disease, and a mixture of Alzheimer's disease and vascular dementia is fairly common.
Lewy body disease
Lewy body disease is characterised by the presence
of Lewy bodies in the brain. Lewy bodies are
abnormal clumps of the protein that develop inside
nerve cells. These abnormalities occur in specific
areas of the brain, causing changes in movement,
thinking and behaviour. People with
Lewy body disease may experience large fluctuations
in attention and thinking. They can go from
almost normal performance to severe confusion
within short periods. Visual hallucinations are also a
Three overlapping disorders can be included with
Lewy body disease:
• Dementia with Lewy bodies
• Parkinson's disease
• Parkinson's disease dementia
When movement symptoms appear first, Parkinson's
disease is diagnosed. As Parkinson's disease
progresses most people develop dementia. When
cognitive symptoms appear first, this is diagnosed as
dementia with Lewy bodies.
Lewy body disease sometimes co-occurs with
Alzheimer's disease and/or vascular dementia.
Frontotemporal dementia involves progressive damage to the frontal and/or temporal lobes of the brain. Symptoms often begin when people are in their 50s or 60s and sometimes earlier. There are two main presentations of frontotemporal dementia– frontal (involving behavioral symptoms and personality changes) and temporal (involving language impairments). However, the two often overlap.Because the frontal lobes of the brain control judgement and social behavior, people with frontotemporal dementia often have problems maintaining socially appropriate behavior. They maybe rude, neglect normal responsibilities, be compulsive or repetitive, be aggressive, show a lack of inhibition or act impulsively.There are two main forms of the temporal or language variant of frontotemporal dementia.Semantic dementia involves a gradual loss of the meaning of words, problems finding words and remembering people's names, and difficulties understanding language. Progressive non-fluentaphasia is less common and affects the ability to speak fluently. Frontotemporal dementia is sometimes called frontotemporal lobar degeneration (FTLD) or Pick's disease.
There are a number of conditions that produce
symptoms similar to dementia. These can often be
treated. They include some vitamin and hormone
deficiencies, depression, medication effects,
infections and brain tumours.
It is essential that a medical diagnosis is obtained at
an early stage when symptoms first appear to ensure
that a person who has a treatable condition is
diagnosed and treated correctly. If the symptoms are
caused by dementia, an early diagnosis will mean
early access to support, information and medication
should it be available.
What are the early signs of dementia?
The early signs of dementia can be very subtle, vague
and may not be immediately obvious. Some common
symptoms may include:
• Progressive and frequent memory loss
• Personality change
• Apathy and withdrawal
• Loss of ability to perform everyday tasks What can be done to help?
At present there is no cure for most forms of
dementia. Some medications have been found to
reduce some symptoms and other therapies can
reduce the rate of progression. The person
diagnosed with dementia can also make plans for
their future and their family can come to
understand what is happening. Support is vital for
people with dementia and the help of families, friends
and carers can make a positive difference to
managing the condition.