Dementia

Dementia

by Dr John Rees

This month in his neurological health series, Dr Rees explores dementia.

Dementia is a frequent condition affecting a predominately older population world-wide, although it may present in middle age and rarely much younger. According to some observers, dementia has reached ‘epidemic proportions’. This is probably because we are all living much longer rather than that there is a significant increase in the causes of dementia.

Alzheimer’s disease, described by Alois Alzheimer in 1906 accounts for about 80% of dementia, 10% of which is familial. It is caused in part by the accumulation of beta amyloid protein and also neuro fibrillary tangles in the brain cortex (where the ‘grey cells’ live). There are a number of similar conditions including, fronto temporal dementia, dementia with Lewy Bodies and a dementia which can also occur in patients with long standing Parkinson’s disease.

Vascular dementia accounts for about 10% of cases. It is due partly to changes in small brain arteries, it is often associated with hypertension in the absence of obvious strokes but can also occur in the context of a number of major strokes.

Dementia can occur in association with some toxins, for example alcohol and the recently notorious nerve agents, in association with some deficiency syndromes eg low thyroid and low B vitamins.

There are many conditions affecting the nervous system that can occasionally present with, or develop into, an associated dementia, eg syphilis and HIV/AIDS, there are also many very rare conditions causing dementia. Huntington’s disease is a dominantly inherited condition causing involuntary movements and invariable dementia, recent research is very exciting.

Finally, serious brain trauma may be associated with dementia.

The typical features are an insidious development of memory loss especially for recent events, confusion, personality change, language difficulties, anxiety, depression and loss of confidence.

The diagnosis is based on the history, an examination and a formal test of cognitive (higher brain) function. Imaging of the brain is ideally performed with an MRI or less usefully a CT scan. The different conditions already mentioned often have specific abnormalities in the various tests, although in the early stages, all tests including brain imaging may be normal. It is essential to speak to a relative or close friend as well as the patient to establish a clear history.

The symptoms of dementia typically result in an impaired ability to function at the individual’s normal level, may result in early retirement if younger and in due course interfere with fully independent living and an increasing dependence on family, friends and social services.

Sadly, treatment is very limited for the vast majority of patients, only rarely can a de ciency or metabolic cause be found and corrected. For the overwhelming majority of dementias, although the details are quite well known the primary cause that results in the brain pathology and then the symptoms that are so distressing, are largely unknown.

There is an enormous research effort in academic departments around the world to better understand the basic mechanisms in order to try and develop lines of treatment. So far, with the exception of drugs such as donepezil which increase the availability of a chemical messenger called acetyl choline to the brain cells which improve memory for 6-9 months, there has been very little pharmaceutical success and many, many failures. The enormous cost of finding and developing new drugs is such that this has resulted in some major pharmaceutical firms pulling out of the ‘dementia area’.

However, there is much that can be done to support and encourage patients and their families through very difficult times and local social services and the Alzheimer’s Society provide absolutely essential services.