LOS ANGELES » Older chocoholics may have a new excuse to indulge their cravings: The dark stuff not only soothes the soul, but might also sharpen the mind.

In a study published today in the journal Neurology, researchers reported that chocolate may help improve brain health and thinking skills in the elderly. The Boston-based team found that older people who initially performed poorly on a memory and reasoning test and also had reduced blood flow to their brains showed improvement after drinking two cups of cocoa every day for a month.

The researchers had set out to test whether chocolate could increase blood flow to the brain during problem solving, boosting performance, after finding in earlier studies that consuming chocolate high in the antioxidant flavanol was associated with better brain and blood vessel functioning. They recruited 60 elderly subjects for the new study. Since they suspected that flavanol would improve the subjects’ thinking skills and blood flow, they randomly assigned subjects to drink either flavanol-rich or flavanol-poor hot chocolate.

The participants drank two cups of hot chocolate every day for 30 days. Before and after the study period, they completed a memory and reasoning test, which assessed their ability to recognize patterns in a series of letters on a computer screen. Additionally, the researchers used ultrasound to indirectly measure the blood flow to subjects’ brains, as well as magnetic resonance imaging, or MRI, to examine subjects’ white matter — the nerve fibers that connect different parts of the brain.

People who performed poorly on the initial cognitive test — about a third of the participants — also had reduced blood flow to their brains and widespread white matter damage. Those who scored high on the test had significantly better blood flow and more intact white matter, indicating that blood flow, cognitive functioning and brain structure were linked.

At the end of the 30 days, the team found that drinking hot chocolate benefited only the subjects who had poor cognitive and neurovascular function to begin with. After the hot cocoa regimen, those individuals showed an 8 percent improvement in blood flow and a roughly 1 minute faster reaction time on the cognitive task. There was barely any improvement among those who had started out with normal blood flow and cognitive skills.

To the scientists’ surprise, there weren’t significant differences in the neurovascular or cognitive changes between the flavanol-rich and flavanol-poor groups, suggesting that something else in the chocolate was causing the improvements. The researchers plan to identify and test this component in future trials, said study leader Dr. Farzaneh A. Sorond, a neurologist at Brigham and Women’s Hospital in Boston.

After identifying the substance, the researchers may even be able to produce it in pill form, said Dr. Costantino Iadecola, a neurologist at Weill Cornell Medical College in New York City, who was not involved in the study.

By showing that blood flow to the brain is associated with cognitive function, the study helps explain earlier findings that people with high blood pressure and other cardiovascular conditions were prone to developing dementia. This, in turn, suggests that the cognitive functioning test and other measures used in the trial may one day serve as cheap, noninvasive methods to screen people for risk of dementia.

Scientists have focused more on treating than on preventing age-related cognitive decline, Sorond said.

"By the time people develop these problems, it’s too late to initiate the drugs we have," she said. "If we could diagnose them earlier, before they have clinical symptoms, using physiological markers, maybe we could prevent the disease or lessen its impact.

The study has its limitations. The ultrasound technique the researchers used offered only an estimate of blood flow to the brain — a precise measurement would require a more invasive method. "This was an easy way to get this information, but not the most accurate way," Iadecola said.

He added that the study was small, and that it was unclear how long the chocolate’s effects would last.

"Will these changes persist after a month of cocoa or go back to where they were before? Would you take the cocoa forever?" Iadecola said. "We don’t know."

Although the study results may tempt some to add chocolate to their diet, Sorond noted that the participants’ food intake was strictly regulated to offset the excess fat and sugar in hot chocolate. For people seeking to keep their brains healthy, she recommends an intervention already known to improve cognitive function: exercise.