When it comes to the brain, studies find size matters

The brain shrinks with age like most everything else in the body. And increasingly, brain researchers are considering the role of brain volume, from childhood to old age, in keeping the mind sharp.

There's not much we can do to make our brains bigger. Genes, nutrition, nurturing, and teen and adult lifestyles largely determine what size and shape the gray and white matter is in by the time we're in our early 20s. The key may be how we handle upkeep throughout life, and whether certain behaviors, vitamins or drugs might aid in preserving brain cells.

Several recent studies seem to support the "cognitive reserve" theory: having a bigger brain to start with provides a cushion against dementia from aging or neurological diseases like Alzheimer's.

In particular, brain imaging studies as well as autopsies show scientists that people with larger brains may be better able to forge new connections to regions of the brain that have not been affected by the plaques and tangles of nerve cells that are the hallmark of Alzheimer's.

Dr. Denise Erten-Lyons, a researcher at Oregon Health Sciences University in Portland, reported earlier this year that among a group of 12 volunteers in their 90s found to have both a lot of plaques and clear minds and good memory before they died had larger brain volume overall, but particularly around the hippocampus region, which is involved in memory formation and storage.

She suspects the select group of seniors didn't really have much bigger brains in teens than other subjects in her study. Maximum brain size data, "may suggest that they really were not necessarily born with bigger brains, but they're more resistant to losing brain instead," the neurologist said.

A study from the Netherlands, published earlier this month in the journal Neurology, found that older people with occasional memory lapses, like forgetting an appointment or a friend's name, have about have a milliliter less volume to their hippocampus than the brain structures of those who reported no memory problems.

Several long-term brain-imaging studies are underway to calibrate how much brain volume is part of normal aging so that more rapid deterioration can be identified. Estimates so far range from 1 percent a year to 2 percent a decade.

But setting the scale may be even more difficult because, genetics aside, so many of us suffer a concussion or two, smoke marijuana or drink alcohol — all shown by research to knock off more than a few brain cells.

The most recent finding on alcohol, published in the Archives of Neurology, found that people who drink even modest amounts had smaller brain volume than people who never drink.

Imaging results from more than 1,869 healthy adults, average age 61, found brain volume was lowest for heavy drinkers (14 or more drinks a week) but that even people who had one to seven drinks a week had more shrinkage than teetotalers. The findings surprised researchers who figured that light drinking levels, known to help prevent heart disease, might also protect against brain shrinkage by aiding circulation.

But volumes of other research show that older people who are socially, physically and intellectually more active are more likely to keep their memory and thinking skills longer. Keeping the blood flowing is important, but mental exercise is also vital.

In fact, a new study from UCLA, soon to be published in the American Journal of Geriatric Psychiatry, found that even staying connected on the Internet by doing searches seems to trigger key centers in the brain that control decision-making and complex reasoning in people aged 55 to 76 — but only among subjects who had experience doing searches.

Still, evidence is growing that a little brain food might help protect against brain volume loss, too.

A British-Norwegian study, also reported in the journal Neurology last month, looked at vitamin B12 levels in the blood of 107 people aged 61 to 87 and also gave them brain scans, memory tests and physical exams. They found that those with the highest levels of B12 were six times less likely to have significantly reduced brain volume than those with the lowest levels of the vitamin.

Although the study doesn't prove that eating more foods rich in B12 or taking a supplement would make a difference to brain volume, "it does suggest that adjusting our diets to consume more vitamin B12 through eating meat, fish, fortified cereals and milk may be something we can easily do to perhaps save our memory," said Anna Vogiatzoglou, an Oxford University researcher who led the project.