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Study sees head size a factor in Alzheimer's cases

LOS ANGELES - For patients with Alzheimer's disease, it helps to have a big head.

That's the conclusion of a study that examined the head circumferences of 270 participants in the Multi-Institutional Research in Alzheimer's Genetic Epidemiology.

Apparently, the extra cranial capacity affords patients some cognitive reserve, resulting in better brain function at any given level of cerebral atrophy.

Researchers had previously noted an inverse relationship between cognitive performance and head circumference. But whether one's "maximum attained brain size" affected the relationship between brain pathology and Alzheimer's symptoms remained unknown, according to the study.

To find out, German researchers working on the study gathered all sorts of data on 270 patients, whose average age was 75.

They also looked up the results of each patient's most recent mini-mental state examination, or MMSE, to measure cognitive function, and they took into account age and ethnicity, how long they'd had Alzheimer's and whether they had diabetes, hypertension or major depression.

Not surprisingly, the researchers found that patients with higher MMSE scores had less severe brain atrophy and had been diagnosed more recently. But head circumference seemed to have no bearing.

Then they adjusted their equations to look specifically for a relationship between brain atrophy and head circumference. At all levels of atrophy, patients with bigger heads were able to get higher MMSE scores.

"Our results support the concept of BR [brain reserve] and underline the importance of optimal neurological development in early life," the researchers wrote. How early? Studies show that brains reach 93 percent of their maximum size at age 6.

The upshot: Alzheimer's prevention efforts should be geared toward the preschool set, the German researchers suggested.The results are in yesterday's edition of the journal Neurology.