New framework defines Alzheimer’s by biology instead of symptoms

Most Alzheimer’s diagnoses occur after symptoms have presented themselves, offering little hope for the patient, as the condition is already at an advanced stage. This could be about to change, however, as researchers have put forward a proposal for the disease to be defined by biology instead of signs of memory loss and cognitive decline.

The framework is a collaboration between the Alzheimer’s Association and the National Institute on Aging in the US. It is thought that move will create a common language to describe Alzheimer’s as distinct from dementia, as well as allowing earlier intervention with preventative drugs.

Dr Clifford Jack of the Mayo Clinic in Rochester, Minnesota, who helped to develop the guidelines, said: “Much of the general public views the terms dementia and Alzheimer's disease as interchangeable, but they are not.”

Three factors take prominence under the new framework: the presence of two abnormal proteins – beta amyloid and tau – which are associated with Alzheimer’s; evidence of neurodegeneration or nerve cell death; and biomarkers that indicate cognitive impairment.

In order to determine where a patient sits within the framework, a number of tests must be carried out. These will include brain imaging and analysis of the cerebral spinal fluid. Better early diagnosis under these terms could lead to more successful drugs trials, as most medicines fail to work on testing, due to the advanced nature of the condition.

It comes in the wake of recommendations from the US Food and Drug Administration and the European Medicines Agency that biomarkers be used to measure the effectiveness of new Alzheimer’s medications in place of clinical symptoms.

Alzheimer’s is the most common form of dementia and is a growing problem across the world, as populations age. Many of the big names in pharmaceuticals are trying to develop treatments for the condition, but failures are rife when it comes to the drugs undergoing clinical trials.

With more than 100 failures, it’s not surprising that some companies are quitting the field altogether. If the way that such trials are approached is changed, however, there could be more chance of success, spelling hope for future generations of Alzheimer’s sufferers.

The majority of the drugs tested have centred around the approach of removing beta amyloid proteins from the brain. Recent studies have shown, however, that around 30 per cent of the patients that have taken part in trials for Alzheimer’s drugs did not have these proteins in their brains to start with, nullifying the results.