MRI scans can be used to diagnose Alzheimer's disease, even before the onset of symptoms of dementia, say researchers.

Alzheimer's disease is currently diagnosed by a process of elimination as many other diseases cause similar symptoms, furthermore a diagnosis of Alzheimer's disease cannot be confirmed until after the patient has died by autopsy. However, results of a study by Ranjan Duara and colleagues at the Florida Alzheimer's Disease Research Center (ADRC) has added to a growing body of evidence which suggests that MRI scans of the brain can be used to diagnose the neurodegenerative disease.

The researchers used a visual rating system to evaluate the extent of atrophy, or shrinkage, present on MRI scans in three parts of the medial temporal lobe of the brain which are vital for conscious memory. They then compared the MRI brain scans of 260 people, which included people with probable Alzheimer's disease, people with varying degrees of mild cognitive impairment (MCI), and a control group of normal elderly with no symptoms of memory loss. Results showed that by using the rating system they could accurately distinguish those with probable Alzheimer's disease from those with MCI, and from those in the control group. Furthermore, the scans even enabled the researchers to identify brain atrophy in some participants who did not have symptoms of memory loss at the start of the study, but who went on to develop memory problems several years later. Thus suggesting that MRI scans could enable doctors to identify those who will get Alzheimer's long before they become symptomatic.

“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,” said Huntington Potter, PhD director of the Florida ADRC.

News release: MRI brain scans accurate in early diagnosis of Alzheimer's disease. University of South Florida Health. December 18th 2008.