Someday, it may be possible with a skin test to positively diagnose someone suspected of having dementia.
The test, developed by researchers in Mexico, also is able to detect abnormal proteins that are specific to Alzheimer's and Parkinson's disease.
According to the group Alzheimer’s Disease International, more than 44 million people around the world suffer from Alzheimer’s, which robs mostly elderly people of their short-term memory. Eventually, the disorder leads to death.
It is the most common form of dementia. But there are other forms of progressive brain disease, such as vascular dementia, which mimics the symptoms of early stage Alzheimer’s and causes cognitive problems. Unlike those with Alzheimer’s, patients can live for years with vascular dementia.
Another progressive neurological disease that can be hard to diagnose in its early stages is the movement disorder Parkinson’s disease.
Now, researchers at Mexico's University of San Luis Potosi have developed a way to diagnose Alzheimer’s and other cognitive disorders, using a small piece of a patient's skin.
Investigators are looking for abnormally high levels of particular proteins that are present in both brain tissue and, it turns out, in skin cells.
Neurologist Ildefonso Rodriguez-Leyva led a study using skin biopsies to diagnose people with various forms of dementia.
“The skin is very closely related with the neurological system because they both have the same origin," Rodriguez-Leyva said. "Then we decided to look for the possibility to find the proteins that were abnormal in the brain — in the skin. And we find them. Skin for us was wonderful.”
Twenty people with a confirmed diagnosis of Alzheimer’s were found to have abnormally high levels of a protein called tau in a 4-millimeter skin sample.
The study included patients with Parkinson’s, who also had elevated tau, as well as abnormally high levels of a protein called alpha-synuclein, compared with healthy individuals.
Currently, diagnosis of Alzheimer's is based on clinical observations, because it is not possible to take brain tissue samples from living individuals for confirmation.
Biochemist Maria Jimenez developed the test. She said skin biopsies offer a noninvasive way to diagnose dementia early.
“Until now, these proteins were only identified in the brain," she said. "And the idea of our work is to find these proteins outside the brain in the skin.”
Prompt diagnosis of Alzheimer’s and Parkinson’s means treatment can begin early in the disease process, improving quality of life.
The Mexican researchers plan to report their findings at the annual meeting of the American Academy of Neurology next month.