University of California researchers are suggesting a combination of magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) and neuropsychological testing to predict the Alzheimer's disease.
In a paper to be published in the October 25 issue of the journal Neurology
, they say that the combination could point to the likelihood of impending AD in patients with mild cognitive impairment (MCI). The impairment is an intermediate stage between the expected cognitive decline of normal aging and the more pronounced decline of dementia.
With age, forgetfulness and other signs of memory loss sometimes appear, prompting elderly individuals to seek a medical evaluation amid fears that they may be experiencing early symptoms of Alzheimer's disease (AD), the most common type of dementia among Americans aged 65 and older.
"I'm extremely excited about these results," said neurologist James Brewer, MD, PhD, an associate professor of radiology and neurosciences and part of the Alzheimer's Disease Neuroimaging Initiative research team at UC San Diego. "The good news is that we can partially reassure those folks who are negative on these tests, at least regarding their next three years. We have never been able to do that before. These individuals, despite having a real memory problem, have no greater risk of near-term dementia than a similarly aged healthy person without a memory complaint."
Unlike other efforts that have evaluated the predictive capabilities of research-based biomarkers, MRI, CSF and neuropsychological tests are all technologies widely available to clinicians.
The researchers found that these available biomarkers significantly improved accuracy in predicting near-term conversion to dementia. In combination, their prediction rate was almost perfect: None of the individuals who tested negative on all three measures went on to develop AD in the three-year follow-up. By comparison, almost 90 percent of individuals who tested positive on all three measures were demented at the end of three years.
The presence of medial temporal atrophy, determined by automated analysis of MRI using an FDA-approved software package, was associated with the likeliest chance of near-term dementia, with a median dementia-free survival time of only 15 months.
Brewer said the findings foretell a paradigm shift in the diagnosis of Alzheimer's disease.
Instead of saying, 'Let's wait a year and see if this gets worse,' our neurologists can say, 'Let's get a volumetric MRI and check back in a month to see if your complaint is due to neurodegeneration.' That ability makes a huge difference in how we proceed. Maybe the memory complaint isn't due to neurodegeneration, but rather it's a side effect of a medication, a sign of depression or someone is simply anxious and worried. Being able to reassure at least some patients that they are not at significant near-term risk of AD is something we never could do in the past, given the high prevalence of the disease."