For Immediate Release
April 23, 2008

Frontal lobe damage can be risky business

Baycrest study has important implications for treating behavioural problems

Toronto, CANADA – It is not unusual for individuals who have suffered a frontal lobe brain injury, as a result of stroke, tumor or severe head injury, to exhibit changes in personality and behaviour. Now scientists have pinpointed two specific areas in the frontal lobes that, when injured, can shift one’s level of comfort with risk.

Led by scientists at the Rotman Research Institute at Baycrest, in collaboration with American colleagues, the study used a computerized gambling task that looked at the way people make decisions in the context of uncertainty. Three groups of individuals were tested – those with brain injuries in the frontal lobes, those with lesions in other parts of the brain, and healthy control subjects.

The gambling task involved guessing whether a “winning” card was among the cards presented face down on the screen. When there were many cards present, the winning card was more likely to be there, but the potential reward was small. When there were fewer cards on the screen, it was less likely to be there but the potential reward was larger. The participant would decide how many cards to have on the screen before stopping the game to turn the cards over. This required making a decision based on the odds and deciding whether to take a risk, with fewer cards on the screen, for the chance at a bigger payoff.

Researchers found that participants with frontal lobe injuries that involved the left orbital and ventrolateral areas made riskier decisions compared to the healthy control group and patients with lesions to any other part of the brain. The left orbital and ventrolateral lesion group preferred to go after the bigger points payoff when there was low probability of success (fewer cards on the screen). This group also showed blunted reactions to choices that didn’t earn them points; that is, unlike other participants, they didn’t adjust their behaviour and continued to take risks for the bigger reward. Researchers were surprised to find that impulsivity – the tendency to make automatic decisions lacking any strategic thinking – was not exacerbated for this group.

“Our findings suggest that behavioural changes that happen after damage to the ventrolateral and orbital areas of the frontal lobes are related to problems involving processing the consequences of our actions (risk-taking) rather than poor inhibitory control over our responses (impulsivity),” said lead author Dr. Darlene Floden, who conducted the study as a psychology graduate with the Rotman Research Institute at Baycrest.

“This work may have important implications for designing interventions to address inappropriate or risky behaviour that can develop after frontal lobe damage and help patients to function more independently, which would be a tremendous relief to their families.”

The study was published in the journal Neuropsychologia (Vol. 46, Issue 1) in January 2008.

Dr. Floden is now a neuropsychologist and researcher in the Centre for Neurological Restoration at The Cleveland Clinic Foundation. Her research colleagues on the Baycrest study included internationally-renowned frontal lobes experts Dr. Donald Stuss (Rotman Research Institute at Baycrest) and Dr. Michael Alexander (Harvard Medical School, and Beth Israel Deaconess Medical Centre); Dr. Cynthia Kubu (The Cleveland Clinic); and Dr. Doug Katz (Boston University School of Medicine and HealthSouth Braintree Rehabilitation Hospital). The Canadian Institutes of Health Research funded the study.

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Baycrest is an academic health sciences centre, internationally renowned for its care of aging adults and its excellence in aging brain research, clinical treatments and promising cognitive rehabilitation strategies. Baycrest is fully affiliated with the University of Toronto.

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For more information on this press release, please contact:
Kelly Connelly, Senior Media Officer
The Rotman Research Institute, Baycrest
416-785-2432, kconnelly@baycrest.org