A study has lent some force to the suggestion that MRI scans, which detect shrinkage in specific regions of the mid-brain, can accurately diagnose Alzheimer's disease before its symptoms interfere with a person's daily function.
Conducted by researchers at the Florida Alzheimer's Disease Research Center (ADRC) in Miami and Tampa, the study has led to findings that are important in the light of many new disease-modifying drugs in trials - treatments that may prevent mild memory loss from advancing to full-blown dementia if administered early enough.
"We advocate, based on these findings, that the criteria for the diagnosis of Alzheimer's disease should include MRI scans," said Dr. Ranjan Duara, medical director of the Wien Center for Alzheimer's Disease and Memory Disorders at Mount Sinai Medical Center who is affiliated with the University of Miami Miller School of Medicine and University of South Florida College of Medicine.
"By incorporating MRIs into the assessment of patients with memory problems, early diagnosis can be standardized and done far more accurately," added the lead author of the study, published in the journal Neurology.
Dr. Huntington Potter, a neuroscientist at the Byrd Alzheimer's Center and Research Institute, University of South Florida, said: "This study demonstrates that MRI brain scans are accurate enough to be clinically useful, both in diagnosing Alzheimer's disease itself at an early stage and in identifying people at risk of developing Alzheimer's."
During the study, the research team used a new visual rating system to evaluate the severity of shrinkage, or atrophy, in the brain's medial temporal lobe - specifically in three structures essential for the conscious memory of facts and events.
Comparing the MRI brain scans of 260 people-who constituted a group with probable Alzheimer's disease, two groups with varying degrees of mild cognitive impairment (mild memory problems), and a control group of normal elderly with no discernable memory loss-they found that scores generated by this MRI-facilitated test accurately distinguished each group from the other and correlated with the types of memory problems most frequently caused by the disease.
According to them, the more extensive the brain atrophy, the more advanced the clinical stage of Alzheimer's disease.
The researchers even found brain atrophy in some people without memory complaints in the beginning of the study, who demonstrated memory decline when assessed a year or two later.
That suggested that MRIs could predict who will get the disease well before signs of dementia become apparent by other diagnostic methods as well as rule out an Alzheimer's diagnosis in people experiencing memory problems, Dr. Duara said.
"If you don't have changes in these three particular areas of the brain, then you don't have Alzheimer's, Dr. Duara said.
The researcher underscored the fact that it was necessary for developing medicines effective enough to prevent the death of nerve cells in Alzheimer's disease that there was a technique to accurately diagnose it at an earlier stage.
"Having an accurate diagnosis will allow us to start using drugs earlier. The earlier treatment begins, the more likely you are to stop disease progression and benefit the patient," Dr. Duara said.
The researchers revealed that most of the participants in their MRI study were enrolled in the clinical arm of the Florida ADRC, which is supported by a grant from the National Institute on Aging.
Dr. Potter, the study's senior author, revealed that the Florida ADRC, the first multi-centre ADRC in the U.S., was critical for the successful implementation of the study.
"To validate any new diagnostic test or treatment, you need a large number of diverse volunteers for good comparisons. Alzheimer's research is a partnership between the scientific community and study volunteers; we need both to solve the complexities of Alzheimer's disease," Dr. Potter said.