Nearly every individual suffers from some sort of memory problem as their age increases. But only a minority develop Alzheimer's Disease. A new study shows that special "structural" MRIs may be able to predict which subjects stand the greatest risk of developing Alzheimer's and which will simply continue to experience annoying but relatively harmless memory problems. This approach will hopefully allow for earlier and more effective treatments in the near future.

The study, performed at the University of California San Diego, involved scanning the brains of more than 300 subjects in order to compare those of Alzheimer's patients to those with mild cognitive impairment (MCI) and establish commonalities. The ultimate goal was to sketch a general progression from the initial condition to the final disease. Results surprised researchers who expected the brain scans of most MCI subjects to very closely resemble each other. Instead they uncovered a near 50/50 divide in the MCI subject group between those brains that displayed physical symptoms of Alzheimer's and those that didn't. While all affected subjects suffered from the symptoms of cognitive impairment, only a slight majority displayed signs of the brain atrophy so common to those entering full-blown dementia or Alzheimer's. This atrophy is a literal brain shrinkage or loss of tissue in the affected areas that may be caused by plaque buildup and reduced bloodflow.

The fact that just over half of the subject pool displayed these physical changes predicted different outcomes for the subjects and a follow-up performed a year later confirmed this: 29% of the impaired group who had obvious signs of atrophy had developed Alzheimer's within a year; that number was only 8% for the minimal-atrophy group, many of whom had not seen any increase in the intensity of their symptoms. Atrophy seems to be the driving factor behind the cognitive declines characterizing full-blown Alzheimer's, and differentiating risky cases from cases of MCI without atrophy is clearly a key to future treatments. The fact that symptoms may not correspond to risk levels makes this finding very important.

MRIs haven't yet developed to the point that they can effectively guide treatment. But they are allowing for clearer distinctions to be made. Memory problems are not necessarily indicative of Alzheimer's, but a single MRI can give subjects a far more accurate picture of the risks they face. And at-risk individuals, particularly those with immediate family members who've been diagnosed with Alzheimer's, should undergo some sort of examination or cognitive test as soon as they experience symptoms of even mild dementia. The chances of subsequent treatment improving their condition are small but too great to ignore.