What causes dementia?

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

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

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 common symptom.

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

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 behavioural 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 behaviour, people with frontotemporal dementia often have problems maintaining socially appropriate behaviour. They may be 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-fluent aphasia is less common and affects the ability to speak fluently.

Frontotemporal dementia is sometimes called frontotemporal lobar degeneration (FTLD) or Pick’s disease.

Is it dementia?

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.

More information about Dementia Waikato

Dementia Waikato is a charitable trust providing free services to support individuals with a dementia diagnosis, their families and care partners.
 
To contact the Coromandel Peninsula Dementia Advisor and for more information about Dementia Waikato see the related link below.