Professor Julie Williams, who is also chief scientific adviser to the Alzheimer’s Research Trust, said “We have been looking at a specific theory about Alzheimer’s disease but our data shows that there are different things going on. We do not really understand what causes common Alzheimer’s disease. In a few years’ time we might have a very good idea of the full picture.”

First, we know that Alzheimer’s disease is characterized by a build-up of proteins in the brain. Though this cannot be measured in a living person, extensive autopsy studies have revealed this phenomenon.

Second, we don’t really know what causes Alzheimer’s. What we know is that age is the number one factor and two certain genes play an important role.

Among these genes, there are two types a) “risk genes” : they are genes that if present in the individual increase the likelihood of developing the disease b) “deterministic gene” : much rarer than risk genes and only found in a few hundred extended families around the world. If you have it, no doubt you will develop Alzheimer’s.

The two genes uncovered by the UK team – CLU and PICALM – are both known to have protective roles in the brain. Changes in the genes may either remove that protective effect or turn the “protectors into attackers”, the researchers said.

One of the team, Professor Kevin Morgan from the University of Nottingham, explained that the pathways highlighted by the discovery include those involved in the turnover of cholesterol and part of the immune system involved in inflammation.

So with these genes, scientist can find ways to lower cholesterol and inflammation in the brain.

The nest question is if we are able in the future to produce drugs to lower cholesterol and reduce inflammation, could we modify the risk of people getting Alzheimer’s disease ?