Posted on Nov 04, 2013 by Ruth Loftus
New research has further highlighted the extent to which Alzheimer’s Disease may be attributable to the genetic makeup of those who develop the condition. It’s a very regular – and almost daily occurrence - to read or hear that a particular disease has been tracked back to a genetic source. We have all long accepted that the key physical features that define us – whether we are short or tall, blonde or dark, even whether we lose our hair at an early age – are all determined before we are born. Therefore, the idea that the ailments which will affect us throughout our life could be as preordained as other genetic characteristics is a daunting concept.
However, the majority of evidence seems to suggest that other than some rare instances, the course of our health throughout life is not as prescribed as our hair colour. In fact, what researchers are suggesting is that some genetic configurations may pre-dispose or increase the probability that a particular condition can arise. Once a discovery such as this has been made, interventions which could lessen the chance for certain conditions to arise could be put in place immediately. Of course, sometimes our environment or lifestyles are to be blamed and failures in our otherwise stable genetic programming caused by external factors can initiate health issues. For example, there is increasing evidence that smoking brings about precisely this sort of genetic change which can then result in lung cancer.
Taking Alzheimer’s as a case study, we are still in the early stages of a particularly challenging and complicated ‘who-dun-it’. At a very complex level, it is now well understood that the disease results in the death of brain cells and sufferers therefore experience memory loss and a distressing disintegration of personality before the condition finally proves to be fatal. What isn’t really understood though is the precise conditions and circumstances that actually trigger this ’brain cell death’.
The most recent research has involved physicians and researchers from 145 different institutions as well as Alzheimer’s patients and those without the condition from across the world (25,000 with Alzheimer’s and 48,000 non-affected).
The size of this sample has meant that it has been possible for the first time to identify a number of genetic features which may be associated with a risk of developing Alzheimer’s. It also appears that these factors may be cumulative, so that as more are found in any individual’s genetic coding, the possibility of their developing Alzheimer’s also increases.
Previously, 11 of these genetic markers had been identified; this research has confined them all and confirmed their significance. Now, a further eleven have been discovered. Specifically, the research highlights areas of the genetic sequence which show variations that occur in Alzheimer’s sufferers but not in others. This doesn’t name specific culprit genes but does identify the locations where further research might be concentrated. So, it is not a question of the genetic detectives boldly unmasking the villain at this stage, but rather deciding where the house to house search should be undertaken.
The aim of detecting these risk genes is not really to identify those who are at risk, or to make diagnosis easier since any single variant only indicates a small risk and some people may never develop Alzheimer’s. Rather, the real goal is to build an understanding of what all of these genes do and take research further to understand whatever it is that is causing or driving Alzheimer’s. Only then will it be possible to create a fuller picture of the disease and look to the development of treatments.
This most recent work has suggested a number of specific biological processes that may be significant, including: the immune system, cell movement controls, intra- cellular molecular transportation, other cell-to-cell connection and the structures that direct the transport of material within cells.
The focus on the immune system is particularly significant as it suggests that a possible cause of Alzheimer’s could be due to a ‘misreading’ by the immune system which incorrectly shuts down systems, or takes other corrective actions that could result in the advent of the disease.
With the disease now affecting some 500,000 people in the UK - a number that continues to grow as the population profile ages – it now absorbs £32 billion of health service expenditure, so research such as this is crucial to finding out as much information as possible and developing treatments to reduce the effects of this unfortunate disease.