Screening for Dementia
This week we have heard calls on the BBC for routine screening for dementia in the over 75s. But is this call realistic given where we currently are in terms of developing an accurate test to diagnose dementia? And why limit screening to the over 75s?
What is dementia?
Dementia is a brain disease, the first signs of which are often memory problems but it goes on to affect many other aspects of brain functioning. It causes changes in mood, judgement, personality, makes it difficult to communicate or cope with day to day tasks and gets progressively worse over time so that the person with dementia is no longer able to care for his or herself.
There is more then one type of dementia. Alzheimer’s disease is the most commonly known dementia and is associated with the build up of defective proteins referred to as ‘plaques’ and ‘tangles’ in the brain leading to the death of brain cells. Vascular dementia occurs where arteries supplying blood to the brain become blocked leading to small strokes which deprive the brain of oxygen and cause the death of tissue in those areas. Lewy body dementia, where the symptoms resemble Parkinson’s disease, is associated with small deposits of a different protein in the brain. Fronto-temporal dementia results from damage to the front of the brain and is associated with a protein similar to but not the same as that seen in the Alzheimer’s ‘tangles’. Dementia may also be seen in patients with Huntingdon’s Disease, Motor Neurone Disease, Progressive Supranuclear Palsy and a number of other conditions.
Why screen for dementia?
Currently we have no disease modifying treatments to offer those with dementia so you may ask what is point of knowing you have it especially before you develop any symptoms? In response to this question most people tend to fall into one of two camps: those who would rather not know and continue to live their life without the shadow of dementia hanging over them, and those who would rather know, no matter how devastating the news, as it allows them to plan for what may lie ahead. However, once effective treatments for dementia become available the situation changes as the earlier a treatment is started the better will be its chances of success. At that point many more people will want to be screened and to start a treatment as soon as possible in the hope that it will stop the disease in its tracks.
The question then remains as to why focus only on the over 75s? Dementia can start as early as 40 and affects around one in twenty people over 65 and about one in five over the age of 80. So, once an effective treatment is available surely screening should be extended to those aged under 75? The demographics of the population have changed; there are now many more people in the older than younger age groups. Accordingly, we have seen an upward shift in pension age and our working lives are now expected to extend well beyond 65 so the over 60s have an increasingly important role to play in wealth generation for the economy. Screening these younger age groups is therefore not unreasonable and the cost of screening and early treatment would be offset by the reduction in health and social care costs that might be incurred by disease progression to a point beyond which treatment was effective, not to mention the reduction in human suffering.
How are we doing on developing a diagnostic test for dementia?
The search for biomarkers (disease indicator substances) in the blood, urine, and cerebrospinal fluid to use in developing diagnostic tests for a whole raft of neurological conditions including dementia has been underway for some time but is fraught with problems. Too many small size research projects, a lack of reproducibility of results, and lack of standardisation of procedures in obtaining and storing the biological samples obtained from patients to name but a few, so not surprisingly success to date has eluded us. And today (6th April) is no different in that in the scientific journal, JAMA, we see Dutch researchers reporting that high levels of a protein called ‘clusterin’ in the blood are associated with the presence of Alzheimer’s disease and its severity but the findings contradict previous findings and more work required.
Call for a national biomarker initiative.
The quest for a reliable biomarker for Alzheimer’s and indeed all the dementias therefore continues. But what we really need is a co-ordinated, realistically funded, inclusive, national initiative to support research into the identification of biomarkers and development of reliable diagnostic tests for dementia and all other forms of degenerative neurological disease. Until that happens, progress in the field will continue to be hampered and earlier and accurate diagnosis along with national screening for dementia will remain some considerable way off.