A new study provides no reassurance for adults struggling to remember where they parked their cars last night or put their keys this morning. The findings confirm many forgetful adults' worst fears: That absent-mindedness may indeed be a very early sign of Alzheimer's disease.
In a paper published in the journal Neurology, a team of Dartmouth University researchers concluded that adults as young as 60 who complained of memory troubles showed patterns of grey matter loss similar to those seen in patients who had been diagnosed with mild cognitive impairment (MCI), a known precursor to Alzheimer's disease.
"This is the first study to show this loss in those who merely complain about their memory," said Robert Santulli, a psychiatrist and study co-author, via e-mail. "There is old lore that 'If you think you have Alzheimer's, then you don't,' meaning that people can't really be objective or accurate about their own cognitive abilities. This study appears to contradict that, in that it shows that people's subjective sense of their own decline is often a more sensitive indicator of problems than even our most sensitive battery of neuropsychological testing."
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Alzheimer's, which currently affects 4.5 million Americans, is a neurological disease characterized by the irreversible degeneration of brain tissue associated with memory and cognitive function.
Led by Andrew Saykin, a psychiatrist and radiologist, the research team compared structural MRI scans of three groups of 40 patients each: those who complained of memory loss but were otherwise healthy, those with diagnosed MCI, and healthy controls. The scientists examined the scans for evidence of deteriorating gray matter, which refers to the brain areas where the cell bodies of neurons are located.
The MRIs revealed that patients with cognitive complaints showed patterns of grey matter loss around the medial temporal lobe and hippocampus, brain regions involved in memory. The patterns were similar to, but less severe than, those seen in MCI patients.
This loss may represent a pre-MCI stage and aid the development of a simple diagnostic test for Alzheimer's disease (AD) in its earliest phase.
That's the hope of Michael Weiner, a radiologist at the University of California, San Francisco and director of the city's Center for Imaging of Neurodegenerative Disease at the VA Medical Center.
"Someday we might have a treatment," he said, "and we might be able to prevent AD and not simply treat it once it occurs."
Currently, medications are only available to treat the symptoms of the disease, but researchers and pharmaceutical companies are searching for drugs that will slow Alzheimer's progression or otherwise modify the disease process.
But any such intervention will require reliable diagnostics to identify the disease at the earliest possible stage.
"Once there is significant brain damage, it's hard to imagine reversing that process," Santulli said. "The real hope for dramatic advancement will come in the area of prevention of damage."