Losing memory: Alzheimer's and Impact Sports
According to the 2015 World Alzheimer’s report, 46 million people live with dementia worldwide, and this is predicted to climb to 131.5 million by 2050. The 21st September each year is World Alzheimer’s Day and neuropathologist Steve Gentleman, from Imperial College London, joined Chris Smith to talk about it. If you look inside the brain of someone with Alzheimer’s disease, what do you see...?
Steve - When I’m looking down the microscope, the disease pathology spreads through the brain in a fairly predictable manner. The first place you’ll see the pathology usually is around the hippocampus, in the cortex next to the hippocampus.
Chris - This is in the temporal lobe part of the brain where we think memories originate?
Steve - That’s right. The first symptoms often are people with Alzheimer’s disease will be that loss of short-term memory, so they won’t be able to lay down new memories. They’ll be able to tell you what they were doing 20 years ago but they won’t be able to tell you where their house keys are.
Chris - What are the specific changes that you see in the brain tissue that tells you that’s Alzheimer’s disease?
Steve - We stage the pathology by looking for abnormal proteins. One of the particular abnormal proteins maps very well with the progression of the disease; it’s called tau and it’s a protein found in the nerve cells.
Chris - You can actually see spots of this cropping up in the brain?
Steve - Yes. It shouldn’t be visible when we look down the microscope but when it’s laid down it’s aggregated, it’s causing problems with the nerve cells; we can actually see it.
Chris - That fits with the idea that you’re losing nerve cells and, if you’re losing nerve cells because of the buildup of this tau protein, then that could be consistent with why you’re losing your ability to form new memories because you’re compromising the cells that do that job?
Steve - Yes, exactly. You’re interrupting that circuitry which allows you to lay down new memories.
Chris - You’ve mentioned the protein tau, but there’s another protein called beta amyloid which is very said that’s the culprit or the cause of Alzheimer’s disease. Why have you avoided telling me about that one?
Steve - You’re right. A beta protein is a part of the diagnostic workup of Alzheimer’s disease but, in general, the clinical picture, the symptoms map much better to the tau pathology.
Chris - One of the things that’s made headlines a lot lately is this question of whether or not sportsmen and women are at increased risk of damage to their nervous system when they indulge in sports that have an element of repetitive head injury? American footballers, soccer players who head balls, rugger players, and so on. Is there evidence to support this?
Steve - There’s been a lot of interest over the last few years in this particular potential risk factor for Alzheimer’s disease. As you say, the NFL in the US, the American football players, colleagues in Boston have described this new pathological entity called chronic traumatic encephalopathy. The pathology seen is thought to be related to that repetitive mild head injury. Interestingly, the pathology is the same protein that’s found in Alzheimer’s disease; it’s a tau problem.
What’s different is it’s localised to certain areas of the brain, probably related to the head injury. As you know, the surface of the brain has got lots of convolutions and at the basis of the troughs, that’s where the pathology is found. Our engineer colleagues have been modeling this and, low and behold, this is where the forces are of a head injury are focused. So that’s a good building evidence that this might be cause and effect.
However, there’s also a lot of other things going on in the brains of these people so, at the moment, we can’t be absolutely certain about cause and effect. There are other disease processes going on, other degenerative diseases, so we need a little bit more work to be able to relate what we see down the microscope to the symptoms seen in these patients during their lives.
Chris - So marrying these two entities together, Alzheimer’s disease and then the repetitive head injury, they both produce evidence of damage having occurred to the brain. In one case it’s a sort of physical injury, in the other something else is causing damage to the brain which manifests as a build-up of this tau protein and possibly the beta-amyloid protein we mentioned. In both cases though there is damage to nerve cells and loss of nerve cells which is going to ultimately affect the way your brain works.
Steve - That is correct, yes. Both of them will involve nerve cell loss, shrinkage of the brain called atrophy, which has been put down to that nerve cell loss.
Chris - What about doing something about it because, obviously, there may be people who are quite worried. Professional footballers like Wayne Rooney who’s just finished his professional career in more ways than one, possibly, who are now quite worried because they’ve spent their lifetime heading balls. What can they do?
Steve - It’s difficult to say. To be perfectly honest we don’t know what the risk is. What’s the relative risk of a head trauma in terms of your life risk of getting dementia? There are well-known risk factors, mainly related to your vascular health. So your brain weighs about one and a half kilos; it’s quite a small proportion of your body weight, but the brain takes a fifth of all the blood coming from the heart, so it very demanding so you need to keep your blood vessels healthy.
Chris - So the motto of that then must be a healthy diet, don’t smoke, exercise?
Steve - Exactly.