There are two types of Alzheimer’s – the comparatively rare, inherited, early-onset form and the non-inherited, late-onset form, associated with ageing. This latter form is becoming more and more common as people live longer but the current explanation known as the amyloid hypothesis relates more to the rarer inherited form.
This explanation states that the disease is caused by excess levels of a protein called beta-amyloid. The Lipid Invasion Model supports this up to a point but argues that, in the late-onset form, beta-amyloid is just one of a number of factors that damage the blood brain barrier, allowing external lipids in.
The Lipid Invasion Model opens up new pathways for research into the detection, prevention and treatment of the disease. It could have parallels in other neurodegenerative diseases, such as Parkinson’s and Motor Neurone Disease, which also disproportionately affect older people and people engaged in certain sports, and might also be associated with damage to the blood brain barrier.
Alois Alzheimer (1864-1915) was the German psychiatrist and neuropathologist credited with identifying the first published case of ’presenile dementia’, later identified as Alzheimer’s disease. His was the first description of the strange behavioural symptoms (poor short-term memory, sleep disturbance and paranoia) and brain pathology (brain shrinkage and the presence of amyloid plaques and neurofibrillary tangles) commonly associated with the disease.
Alzheimer’s disease is the most common form of dementia affecting 24 million people, mostly in the western world. There is now a one in three chance that we will get it in old age.