Alzheimer’s disease: the value of accurate diagnosis

These are the very things that Alzheimer’s disease steals away and never gives back. Alzheimer’s can progress gradually or quickly, but patients inevitably lose their memory, their ability to think, to plan, to recognise even those closest to them. Their entire identity is essentially lost both to the world and to themselves.

Helen Rochford-Brennan, Chairperson of the European Working Group of People with Dementia, speaks of the “lonely, bleak drive home from the doctor’s office” after learning she had early-onset Alzheimer’s disease.

“I had a wonderful career, an active life, and it was almost impossible to accept that all that was in the past and that life would never be as it was,” she says.

Affecting around 50 million people worldwide, dementia stands as one of the 21st century’s most challenging health problems. The number of people with dementia is expected to triple – meaning that by 2050 more than 150 million will be affected.1 Alzheimer’s disease (AD) is the most common type of dementia, usually striking older adults but also occurring in people as young as their 30s or 40s.2

Healthcare systems are already having serious difficulties coping with the current incidence and may be overwhelmed in just a decade or two by the sheer number of Alzheimer’s patients needing care. A recent report into the true cost of Alzheimer’s disease found that indirect and intangible costs are borne by family and caregivers, with the cost of informal family care accounting for 70% of lifetime dementia care costs.3

Currently, the diagnosis of AD is largely based on clinical symptoms, including cognitive testing, with a significant number of patients diagnosed when their disease has already advanced. Symptoms usually emerge after the age of 60 although people with certain rare genetic mutations may develop the disease earlier. A diagnosis of AD based on cognitive measures alone is only correct in 70-80% of cases. Even with imaging studies such as computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET), the diagnosis might not be conclusive.4

“This means that up to 25% of families have been told their loved one has Alzheimer’s disease and they don’t,” says Dr Jeffrey Cummings, Cleveland Clinic Lou Ruvo Center for Brain Health (Cleveland, Ohio). “Which also means that up to 25% of people participating in some type of clinical trial don’t actually have Alzheimer’s disease.”

New tests have been developed that are based on biomarkers found in cerebrospinal fluid (CSF), the fluid found in the spinal column and around the brain. CSF acts as a cushion for the spine and brain, brings needed supplies from blood, and takes away the brain cells’ waste products.

This fluid can contain peptides that have been closely linked to Alzheimer’s disease: beta-amyloid and tau protein (neurofibrillary tangles). In a healthy brain, these beta-amyloid peptides are broken down and eliminated; in a person with Alzheimer’s, they bunch together and form hard, insoluble plaques. The tau protein neurofibrillary tangles – twisted, insoluble fibers made up of the tau protein forming structures called microtubules – normally transport nutrients and other important substances from one nerve cell to another. With Alzheimer’s, the protein is abnormal and the microtubules are unstable. The new tests for beta-amyloid and tau protein can provide clinicians with critical information to help them make a faster, accurate diagnosis.5

With no cure for Alzheimer’s, is there really any point to being tested and diagnosed with the disease? Experts answer with a resounding yes, for several reasons. An accurate diagnosis made as early as possible is “tremendously important,” Dr Cummings observes.

“We know that patients are being diagnosed far too late in the course of their clinical disease,” he says.

Although many studies of promising drugs have had negative results, researchers were able to learn more about this devastating disease and gain deeper understanding of how to design clinical trials and identify which patients should be included. For example, scientists now understand that the treatment approach for patients in early stages of the disease should be different from the approach for those in later stages.

And what is clearly evident is that, as with cancer, detecting and diagnosing Alzheimer’s early is vitally important. The earlier the treatment starts, the more likely it is to have a positive effect on how the disease progresses. For clinical trials, knowing that the participating patients really have Alzheimer’s and not another form of dementia gives more confidence in the results.

“There are treatments for Alzheimer’s that improve the symptoms and that often help people function better for a longer period of time,” says Rachelle Doody, MD, Global Head of Neurodegeneration at Roche. “And one reason for having an early diagnosis of Alzheimer’s disease is the opportunity to participate in clinical trials that may benefit society and the future.”

For people with Alzheimer’s disease, like Helen, there is real value in raising awareness about the importance of diagnosis and in learning about the research and clinical trials available that may lead to effective treatments that could transform Alzheimer’s disease.

“With the right diagnosis and support, we can live with this condition,” she said. “We are seeing dementia-inclusive communities thanks to advocacy work. And as an advocate, I am hoping to create a better quality of life that we can all benefit from. No, we do not have a cure right now. But we do have hope.”

References

1. World Health Organisation. Dementia. [Internet; cited 2019 Nov 13]. Available from:

2. Alzheimer’s Association. Younger/Early Onset Alzheimer’s [Internet; cited 2019 Nov 13]. Available from:

3. El-Hayek YH, Wiley RE, et al. Tip of the iceberg: assessing the global socioeconomic costs of alzheimer’s disease and related dementias and strategic implications for stakeholders. J Alzheimers Dis. 2019:70:321-339.

4. Gaugler JE, et al. Characteristics of patients misdiagnosed with Alzheimer’s disease and their medication use: an analysis of the NACC-UDS database. BMC Geriatrics. 2013;13;137.

5. Alzheimer’s Society. Dementia Update UK. [Internet; cited 2019 Nov 13] Available from: