Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that causes damage to the brain cells which control memory and thinking. While the precise mechanisms of the disease remain unclear (one reason why there are no cures yet), it is known that AD is characterised by the accumulation of proteins, known as beta-amyloid and tau, and that this protein build-up is associated with brain cell death.
Doctor Dennis Chan talks about Alzheimer’s disease, how it is diagnosed, his research and how virtual reality can help spot the early signs of the disease.
The toxic accumulation of beta-amyloid and tau proteins starts years and possibly decades before people develop symptoms of Alzheimer’s. As the brain circuits get progressively damaged, people begin to exhibit symptoms, such as memory decline and navigational difficulties (getting lost). At this stage, they are considered to have mild cognitive impairment.
As the disease worsens, other aspects of brain function get affected. People lose the ability to undertake normal daily activities and at this stage people with AD develop dementia. So AD is a cause of dementia but is associated with an earlier, pre-dementia stage.
How can Alzheimer’s be detected?
AD is detected by careful evaluation of symptoms, as declared by the affected person and also by their family and friends, then with a neurological examination to rule out other conditions such as a stroke or Parkinson’s disease.
A clinical assessment is then carried out to test memory and thinking, currently via pen-and-paper tests and MRI brain scanning. The latter is required, not just to rule out other potential causes of memory decline (such as strokes or cysts) but to look for the patterns of brain shrinkage that are characteristic of AD. CT scanning does not have the same image quality as an MRI, so the latter is the preferred option. High-resolution MRI scans that give the highest quality brain images are by far the best.
However, during the earliest stages of the disease, when people have mild cognitive impairment (MCI) rather than dementia, it can be hard to diagnose Alzheimer’s. A detailed evaluation from an expert clinician is required. MCI can be very hard to distinguish clinically from memory decline due to normal ageing or anxiety. Pen-and-paper tests alone cannot distinguish between the two and MRI scans may be normal in the early stages.
There are more sensitive diagnostic tests, for example; lumbar puncture of spinal fluid levels of the Alzheimer proteins beta-amyloid and tau, but these tests are not widely available and at present, are only accessible via neurology-led specialist memory clinics. It is possible to identify these proteins on PET nuclear medicine brain scans, but such PET scans cost thousands of pounds and so their use is not supported by the NHS.
How can virtual reality help to spot early signs of Alzheimer’s?
Research by Dr Chan has shown that a virtual reality (VR) test is superior to the current gold-standard pen and paper tests when it comes to detecting pre-dementia AD. This is because the VR test is probing the function of the brain circuits affected at the very earliest stages of AD.
Another advantage of the VR test is that it is probing a function that is performed in real-life (navigation) and so it has a greater real-life relevance (also known as “ecological validity”) than pen-and-paper tests which ask people to copy shapes like intersecting pentagons or to subtract seven from 100 five times over.
The problem with such tests is that they are artificial, copying pentagons is not something people normally do in everyday life! They have some value in detecting people with dementia but have little value in detecting people with pre-dementia AD whose thinking ability is relatively preserved.
What are the early signs of Alzheimer’s that VR can detect?
The VR test detects changes in our ability to navigate. It is based on extensive scientific understanding of the function of brain cells within the regions first affected by AD, damage to which contributes to a worsening sense of direction that can occur at the beginning of AD. These brain cells (termed place cells, head direction cells, border cells and grid cells) code spatial information. They underpin our ability to navigate from place to place and to remember places as well as objects within those places. The scientists who discovered these cells were awarded the Nobel Prize in Medicine in 2014. It was their work that prompted the design, then the application of the VR navigation test.
How can we best protect ourselves from Alzheimer’s?
Maintaining good physical health (avoiding diabetes, high blood pressure, a balanced healthy diet and normal weight, not smoking or drinking alcohol to excess) is important but above and beyond that, there is good evidence that high levels of engagement in physical (e.g. sports, walking), social (e.g. seeing friends and family) and intellectual (e.g. reading, playing musical instruments) activities help to maintain brain function into older age.
The good thing about such activities is that they are backed by robust scientific evidence (unlike advertised food and other supplements which are not backed by any good evidence), they don’t have to cost anything and can be undertaken by everyone.
If you’d like more information regarding Alzheimer’s and its detection, get in touch with Dr Chan.