Not all elderly people with Alzheimer's-like behaviors will be diagnosed with Alzheimer's disease as researchers propose a way of defining the disease based solely on biomarkers.
The plan is part of an industry-wide effort to improve treatment approaches to Alzheimer's disease. It is reported that clinicians are urged to rely on biomarkers such as brain scans rather than behavioral symptoms such as memory loss.
"We are proposing that the disease be defined in living people by evidence of brain pathology using biomarker studies, either brain imaging or body fluid examination, and that clinical symptoms should be regarded for what they are — a product or result of the disease, as opposed to the definition of the disease," said lead author Dr. Clifford Jack, Jr. of the Mayo Clinic.
The details of the proposal, presented in 2011, were published April 10 in Alzheimer's and Dementia.
Resolving Inconsistencies
Prior to the presentation of the new framework, the National Institute on Aging and Alzheimer's Association published three articles on diagnostic recommendations for the preclinical, mild cognitive impairment, and dementia stage of Alzheimer's disease.
There were inconsistencies observed in the data in line with the currently accepted science. The intent, according to Jack, is to have a common language for researchers in the Alzheimer's field in terms of disease categorization.
The authors emphasized that dementia is a syndrome, which exhibit signs and symptoms that can be associated with other diseases related to Alzheimer's.
One of the inconsistencies mentioned by Jack is that 10 to 30 percent of patients diagnosed with Alzheimer's do not show relevant neurological changes. This means that they have normal findings in amyloid positron-emission tomography or cerebrospinal fluid — two factors that are directly linked to Alzheimer's.
On the one hand, 30 to 40 percent of individuals who do not show any cognitive abnormalities were found to have neuropathologic anomalies.
However, Maria Carrillo, the chief scientific officer of AA, said this new framework is still subject to testing, and it is not meant to be used in doctor's offices.
Early Intervention
One in 10 Americans aged 65 years and above has Alzheimer's disease, according to the AA 2017 Alzheimer's Disease Facts and Figures.
The population of at-risk individuals is expected to grow rapidly at double the rate from 48 million to 88 million by 2050. Women have higher risks of developing Alzheimer's related diseases compared to men at 16 percent and 11 percent respectively, based on the Aging, Demographics, and Memory Study.
Researchers believe they can also help patients showing normal brain images who are still at risk of dementia once the document is implemented into practice.
Jack said they are expecting that more people will be diagnosed with Alzheimer's because brain scans and spinal fluid can show signs 15 to 20 years before the onset of symptoms.
By detecting Alzheimer's gene earlier, clinicians can do early interventions to reduce symptoms.
"By the time that you have the diagnosis of the disease, it's very late. What we've realized is that you have to go earlier and earlier and earlier," said Dr. Eliezer Masliah, chief of neuroscience at the Institute of Aging.
