Scientists in Australia and Japan say they have made important progress in developing a blood profile test that could in future help physicians detect who might go on to get Dementia’s disease.
The scientists said the test, which can detect a toxic protein known as amyloid beta, linked to Alzheimer‘s, was more than 90 percent accurate in research involving around 370 people, according to the study published in Nature Journal.
Alzheimer’s is the most common form of dementia, a general term for memory loss and other cognitive abilities serious enough to interfere with daily life. Alzheimer’s disease accounts for 60 to 80 percent of dementia cases, affects close to 50 million people worldwide and is expected to affect more than 132 million by end of 2050, according to the non-profit campaign group Alzheimer’s Disease International.
In a previous study by Dr Natalie Ryan and colleagues, of University College of London, UK, has found that the way Alzheimer’s manifests in individuals depends on their age as well as the positional mutations in the gene. For this reason, all young adults with dementia and other neurological conditions should undergo genetic testing for appropriate diagnosis and (if possible) treatment.
Alzheimer’s, the most common form of dementia, is the progressive brain disorder that gradually destroys a person’s memory and thinking skills. It has a slow onset and develops over the years but once it starts, it is irreversible.
It can affect anyone but is most prevalent in older adults aged 65 and older. UK Alzheimer’s Society reports that in 2015, there were around 850,000 people with dementia in the UK. The count is expected to bulge to one million by 2025. The story is much more horrific in the US where approximately 5 million Americans are living with Alzheimer’s.
Alzheimer’s is a clinical mystery. It is little understood which makes it a mammoth clinical challenge for doctors and researchers. And there is currently no treatment available for this disease. In fewer than 1% of the patients, Alzheimer’s is caused by mutations in autosomal genes. The condition is called autosomal dominant familial Alzheimer’s disease (ADAD).
Dr Natalie Ryan, researcher at Dementia Research Center, University College London and the lead author of the study writes:
“Alzheimer’s disease is caused by autosomal dominant mutations in the presenilin 1 (PSEN1), presenilin 2 (PSEN2), or amyloid precursor protein (APP) genes.”
Trials are underway to understand the genetic cause of the disease but Dr Ryan believes more needs to be done. In the study, published today in The Lancet Neurology, she writes:
“Prevention trials for ADAD are underway and have stimulated research into biomarker changes in preclinical Alzheimer’s disease. However, these trials also necessitate better understanding of the natural history of Alzheimer’s disease in the symptomatic phase and of factors that influence age at onset.”
To understand the clinical phenotypes and genetic associations in ADAD, Dr Natalie and colleagues designed a study where they retrospectively analyzed data, including age at symptom onset, cognitive and neurological symptoms including seizures, of all the patients (n = 213) with ADAD enrolled in the Dementia Research Center between July 1987 till October 2015.
The researchers also studied genotype of APOE, PSEN1, PSEN2 and APP genes, their mutational position and the heterogeneity between phenotypic differences between APP and PSEN1 mutation carriers. Of the total patients, the researchers identified 38 different genetic mutations in PSEN1 genes and six in APP genes.
What was interesting is that the patients who were younger – 43 years or younger — showed a genetic mutation in PSEN1 indicating the significance of this region. Older adults – 50 and above – showed APP mutations.
Of the young adults showing PSEN1 mutations, approximately 84%, and 97% of older adults presented with amnestic symptoms. Most of the patients also had myoclonus and seizures – 47% with PSEN1 mutations and 33% with APP mutations.
The researchers concluded that ADAD manifests itself differently in individuals depending upon their age as well as the mutational position of the causative gene. Dr Natalie mentioned and recommended that it is, therefore, extremely important that all young individuals with dementia or other neurological degenerative disease undergo an early genetic testing to diagnose, treat and halt the disease progression.
Responding to the study, Wiesje M Van, of Department of Neurology and Alzheimer’s Center and Department of Epidemiology and Biostatistics, wrote that recognizing clinical heterogeneity is not only extremely important, but also forms the foundation of diagnosis in Alzheimer’s. A correct diagnosis of Alzheimer’s is the starting point for best patient and disease management.
Diagnoses are often missed in Alzheimer’s, particularly in patients that present with atypical symptoms. Understanding heterogeneity, Van argues, can be the answer to the puzzle that Alzheimer’s is and may provide key to finding treatment.