Could people we believe are suffering from Alzheimer’s disease actually be misdiagnosed and therefore not benefiting from an appropriate response?
Research led by Peter Nelson of the University of Kentucky’s Sanders-Brown Center on Aging (published in the journal: Acta Neuropathologica) describes criteria for a disease called “Primary Age-Related Tauopathy”, or PART, which displays symptoms very similar to those of Alzheimer’s but without the amyloid plaques associated with the well-known disease and might have been confused with Alzheimer’s until now.
“To make an Alzheimer’s diagnosis you need to see two things together in a patient’s brain: amyloid plaques and structures called neurofibrillary tangles composed of a protein called tau,” says Nelson. “However, autopsy studies have demonstrated that some patients have tangles but no plaque and we’ve long wondered what condition these patients had.”
Amyloid plaques, which result from a buildup of amyloid-based proteins, have always been considered a definitive sign of Alzheimer’s disease. Until now, when tau tangles were observed without accompanying amyloid plaque, it was assumed that the disease was in its early stages. Whereas earlier research had found that amyloid-beta proteins that are incorrectly folded can subsequently cause tau proteins to become misshapen, some patients displayed the latter without the former.
Since plaques are evidence of Alzheimer’s, patients displaying tangles without plaque can now be diagnosed with PART. Alzheimer’s treatments, until now, which have focused on fixing the amyloid plaques, might prove useless for PART sufferers. Therefore, new solutions will have to be found before these types of patients suffer from irreversible neural degeneration.
“Until now, PART has been difficult to treat or even study because of lack of well-defined criteria,” Nelson adds. “Now that the scientific community has come to a consensus on what the key features of PART are, this will help doctors diagnose different forms of memory impairment, early. These advancements will have a big impact on our ability to recognize and develop effective treatments for brain diseases seen in older persons.”
This new discovery leaves us unclear about exactly how many people suffer from PART. Certain studies found that a fourth of patients diagnosed with Alzheimer’s actually have intact amyloid and could be re-categorized as PART cases. The new, more definitive criteria for diagnosing PART will hopefully help researchers and medical experts develop more effective treatments and medicines.