Cholesterol increases Alzheimer’s risk

It has been known for a while now that cholesterol, particularly LDL cholesterol (bad cholesterol), increases your risk of Alzheimer’s and heart disease. But until recently nobody has understood why.

A new study, published in the online journal PLOS ONE, has found that cholesterol causes cells to divide incorrectly. For those who haven’t brushed up on their biology, here’s a quick, simplified lesson:

Every cell in your body contains a copy of your DNA. This is stored in chromosomes. Each cell has 46 chromosomes, or 23 pairs. They are labelled by number, from one to 23. To make new cells (which the body is doing all the time), a single cell will make a copy of your DNA. For a very short time that cell will have two copies of your DNA. The cell then splits in half. Each half gets a set of chromosomes, or one complete copy of your DNA. Both cells are identical to the original one they were created from.

Now for a segue. People with Down Syndrome have something called ‘trisomy 21’. Every cell in their body contains three copies of chromosome 21, instead of the usual pair. This is important because this new piece of research has found that cholesterol causes trisomy 21 in the cells which are dividing incorrectly.

Previous studies have shown that as much as 10 per cent of the cells in an Alzheimer’s patient, including neurones in the brain, have trisomy 21 (or three copies of chromosome 21 instead of two). Thus Alzheimer’s disease is, in some ways, an acquired form of Down Syndrome.

Now for the tricky part. Chromosome 21, the one which is being affected by cholesterol, is the chromosome which tells your body to produce the key component of the neurotoxic amyloid filaments which accumulate in the brain of Alzheimer’s patients.

Confused? Basically what this means is we knew one of the causes of Alzheimer’s and now we know why it’s happening. That means we are much closer to being able to create a preventative measure or a cure than we have been previously. And who wouldn’t want to cure Alzheimer’s?