Utilizing diffusion tensor imaging (DTI)--along with MRI--to calculate high mean diffusivity values of the hippocampus is a better predictor of memory decline and the brain changes associated with Alzheimer's disease than MRI alone, said a study published online yesterday in Neurology.
The cross-sectional study, which was supported by the Italian Ministry of Health, investigated age-related memory decline compared to hippocampal anatomic changes in a group of healthy individuals to determine a possible relationship.
Giovanni Carlesimo, PhD, of Tor Vergata University in Rome, and colleagues examined the hippocampal anatomic changes by way of DTI-MRI brain scanning in a group of 44 healthy males and 32 females ranging in age from 20 to 80 years, all of whom had experienced memory loss.
According to the authors, utilizing DTI and MRI provides a more sensitive way of detecting changes in brain chemistry and thereby mapping fiber tracts that connect brain regions more efficiently than MRI alone.
The 76 study participants, who were recruited from universities, community recreational centers, hospital personnel and patients’ relatives between 2005 and 2008, underwent 3T MRI protocol with a whole-brain T1-weighted and diffusion-weighted scanning and a neuropsychological assessment.
DTI changes in the hippocampus, a region of the brain that is critical to memory and one that is involved in Alzheimer's disease were noted by the researchers. Hippocampus changes that were studied included the volume of the total brain (gray and white matter) and the values of mean diffusivity (MD) and fractional anisotropy (FA) were calculated, said the study.
The neuropsychological assessment portion of the study included tests of verbal memory (15-minute delayed recall of a 15-word list) and visuospatial memory (20-minutes delayed reproduction of Rey complex figure).
The researchers found that that mean diffusivity in the hippocampus more likely predicted verbal and visuospatial memory performance in the participants over age 50 or older than their younger patient population, and also discovered that the changes picked up by DTI scanning better displayed memory decline compared to measuring hippocampus volume through a traditional MRI.
"DTI, along with MRI, could serve as an important tool in understanding how and why a person experiences memory decline,” concluded Carlesimo. “Our findings show this type of brain scan appears to be a better way to measure how healthy the brain is in people who are experiencing memory loss. This might help doctors when trying to differentiate between normal aging and diseases like Alzheimer's.”