Alzheimer’s disease explained

This is a bold title for a blog on a disease that still requires a lot of discovery.  But it’s possible to explain what we know so far.  Alzheimer’s disease is well known as a condition that mainly affects older people and causes them to have memory problems. 

That’s not the half of it, even though both those things are true.  The doctor who named it first wrote about a patient who was suffering from memory loss, language problems, and unpredictable behaviour.  He reported the post-mortem finding of abnormal clumps in her brain histology. Neurologists now know that those abnormal findings can be detected in brains where the person never had dementia, so the relationship is still puzzling.

“Alzheimer’s disease is the most common cause of dementia, although many people with dementia have mixed causes, such as Alzheimer’s and vascular at the same time.”

Those clumps are often called “plaques and tangles”.  We now know that there is a loss of connections between the nerve cells in the brain.  The chemical that passes between neurons (brain cells) in order to transmit messages is acetylcholine.  This neurochemical transmitter is not only found in the brain.  It’s active in other bodily functions, for example cardiac contractions, blood pressure, intestinal peristalsis, glandular secretion.  It is broken down by an enzyme called acetylcholinesterase.  Some of the medicines that are given to slow the progress of Alzheimer’s disease inhibit that enzyme, giving the acetylcholine a better chance to work.  The aim is to prolong the thinking capacity that the person has.

The most common cause of dementia

Alzheimer’s disease is the most common cause of dementia, although many people with dementia have mixed causes, such as Alzheimer’s and vascular at the same time.  The risk of any person getting Alzheimer’s disease increases with age.  It’s a progressive disease.  There are some very rare and unusual people who have been diagnosed with Alzheimer’s but who are still functioning very well years later.   In general people go downhill over many years.  It is hard to say how long because it depends when you start to count.  Some people never get a diagnosis, and some are only diagnosed at the very end of life, when it is put in the death certificate.  Families of people who are undergoing investigation will often tell you that, looking back for years, they can now see with hindsight that the person has been changing for a long time before anyone got worried enough to see a doctor. Those people may have started to have difficulty planning or making decisions.  Their personality may have changed, often for the worse but not always.   

It is a life-limiting disease.  Because most of the people affected are very old, they may well die of something else, but because it is a progressive neurological condition it can lead to frequent chest infections, perhaps caused by food or fluid going “down the wrong way” into the lungs.  It’s common for the person to have difficulty eating and a reduced appetite.  The fact that the sense of smell is reduced also contributes to this, along with apathy and not taking pleasure in things that used to please them, like a tasty meal, or a nice cake.

New medications

The new medications that are being brought forward are trying to chemically reduce the plaques and tangles, but they have unfortunate side effects, and sometimes the severity of the plaques and tangles is not directly related to the severity of the dementia symptoms.  It’s very disappointing. 

The best we can do is to help reduced the symptoms, and there is a lot of information about how to do that on this website and in the one-stop guide called Dementia.