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What is Dementia?

Dementia is a general term that describes a number of different illnesses which lead to a decline in mental or cognitive function. The most well-known of the dementias is Alzheimer’s disease. Dementia is an illness which is rapidly increasing in prevalence, mostly due to the ageing of the population. In fact, the main risk factor for dementia is age. In Australia, the 2006 estimated prevalence of dementia is 1% of those aged 60-65, 6% of those aged 75-79, and 45% of those aged 95 or older (Alzheimer's Australia, 2005).

Types of Dementia

One way of distinguishing types of dementia is to compare the age at which a person’s symptoms began. Younger onset dementia refers to cognitive changes which start prior to the age of 65 whilst later onset dementia refers to changes after the age of 65. Although later onset is the most common type, it is estimated that there are over 11,000 people in Australia with younger onset dementia.

There are many different diagnostic types of dementia. These include Alzheimer’s disease (the most common type of dementia), vascular dementia, frontotemporal lobar degeneration (including frontotemporal dementia, progressive non-fluent aphasia, semantic dementia and Pick’s disease), dementia with lewy bodies, dementia associated with Parkinson’s disease, dementia associated with Huntington’s disease, dementia secondary to alcohol and/or drug abuse, HIV/AIDS related dementia, dementia secondary to Down’s syndrome, dementia associated with multiple sclerosis and prion diseases such as Creutzfeldt-Jakob disease.

Symptoms

There are different symptom profiles which are associated with each of the above types of dementia. Generally though dementia is associated with a loss of mental or cognitive function. People with dementia often have changes in their memory (more recent information is generally harder for them to remember), a decline in their planning and judgement, word-finding and language difficulties and problems with maintaining and focusing their attention. They usually also have changes in their behaviour and personality such as becoming less motivated, more irritable and more anxious and later on some people with dementia may also experience delusions such as the belief that someone is stealing from them. All of these symptoms are often accompanied by problems with daily activities such as driving, managing finances and cooking.

Diagnosis

In order to diagnose someone with dementia it is necessary that they have a test of their mental function. The test that is most commonly used is the Mini-Mental State Examination (MMSE) although some doctors are starting to use more sophisticated methods to determine a person's brain function. In addition to cognitive testing, it is usual for a doctor to talk to a family member in order to evaluate how a person is performing their daily tasks. A blood test, brain scan (usually a CT or MRI scan) and physical and neurological exam will also usually be performed.

Treatments for Dementia

It is important to note that dementia is not necessarily irreversible and some forms can be treated. These forms are quite unusual but it is always suggested that a person have a blood test and be screened for depression if it is suspected that they have dementia. For example, depression is a very common disorder and problems with memory and/or planning is one of its symptoms whilst deficiencies in vitamins B12 and B1 (thiamine) and also hypothyroidism can lead to dementia.

Once a diagnosis of irreversible dementia has been made the person can commence on medications which are designed to slow down the course of the disease and keep the person stable for as long as possible. There are different medications and treatment regimens for the different types of dementia. The most common medication to slow the onset of dementia is the class of drugs known as cholinesterase inhibitors. Cholinesterase inhibitors work by preventing the breakdown of acetylcholine, a chemical which helps with memory and which enables cells to communicate. In particular they have been shown to slow the decline of mental functions and to improve motivation. Examples of these medications are Aricept and Exelon. Memantine is another drug which is often used and this medication works in a slightly different way. Memantine blocks the NMDA receptors so that glutamate levels can be better regulated. Glutamate is involved in the processing and storage of information and too much glutamate is thought to lead to cell death. This medication has been shown to aid cognitive and and psychomotor skills and to improve independent function. Other medications such as antidepressants and antipsychotics may additionally be prescribed to help with any behavioural symptoms such as depression or agitation.

Who to Contact if You Need Advice or Information

The following organisations specialise in providing information for people with dementia and for their carers and family members.
Dementia Estimates and Projections: Australian States and Territories. Alzheimer's Australia (2005)