The researchers reported in Neuropsychology on their study, which included 40 participants who are part of a long-term study at UCSD Alzheimer's Disease Research Center.

Although all participants were symptom-free when they took the test, 20 patients were diagnosed with Alzheimer's disease within a year or two of testing, while the other 20 have remained symptom-free several years later.

The investigation included naming common items from pictures, and reconstructing drawings of block structures using actual building blocks.

Researchers found that the pre-Alzheimer group "had much greater performance gaps between their ability to name objects and their ability to reconstruct the block images."

Comparatively, members of the control group had much lower performance gaps, and performed more consistently in both areas.

"We saw a largest discrepancy between the results of the non-verbal spatial tests and the verbal tests in the subjects who later were diagnosed with Alzheimer's disease," said Mark Jacobson, Ph. D., research psychologist with the VA Healthcare System, assistant project scientist with the UCSD department of psychiatry, and lead author of the study.

"Since these changes are very subtle and not noticeable if you are only looking at one single area, our findings suggest that we should be comparing performance in different areas as they relate to one another to detect early changes in cognitive function," Jacobson said.

Results of the study could be useful in detecting early signs of the disease in people who otherwise are symptom-free, are at high-risk, or have a family history of the disease, the researchers said.

"The current study highlights the importance of considering alternative methods of defining cognitive changes by analyzing subtle cognitive discrepancies in people at risk for (Alzheimer's disease)," they concluded.

Other Sources: Neuropsychology, University of California San Diego