Bipolar Math Subtractions: Mental disorder may spur math problems in teens

The severe psychiatric ailment known as bipolar disorder takes individuals on an emotional roller-coaster ride over dizzying peaks of agitation, euphoria, and grandiose thinking and through valleys of soul-numbing depression. New evidence suggests that an unappreciated facet of bipolar disorder has nothing to do with rampaging emotions. It involves a deterioration of mathematical reasoning, at least among teenagers.

Reasons for the emergence of math difficulties in adolescents who develop bipolar disorder remain unclear, according to a report in the January American Journal of Psychiatry. The illness may affect any of several brain areas that have been implicated in mathematical reasoning, propose Diane C. Lagace of Dalhousie University in Halifax, Nova Scotia, and her colleagues.

“[Our] findings suggest that remedial academic interventions in mathematics are warranted for adolescents with treated bipolar disorder,” the scientists conclude. These “novel findings” need to be confirmed in larger samples of teens and adults with bipolar disorder, the investigators add.

Dalhousie researchers had previously noted a link between math problems and bipolar disorder. Their 1996 review of medical and academic records for 44 teenagers with the illness found that they had performed well in school until the onset of psychiatric symptoms. While the students received treatment for bipolar disorder over the next 4 years, their school performance deteriorated far more in math than in any other subject.

In the new study, the scientists administered academic and intelligence tests to three groups of teens: 44 taking prescribed medications for bipolar disorder and whose symptoms had largely diminished, 30 who had responded well to treatments for major depression, and 45 who had no past or current psychiatric ailment.

The teenagers with bipolar disorder scored much lower on a broad range of math problems than those in the other two groups did, the researchers say. This math deficit appeared regardless of whether the participants had a limited or unlimited amount of time to solve each problem. Girls with bipolar disorder scored much lower on math tests than their male counterparts. A less pronounced sex disparity in math scores appeared in the other two groups.

In contrast, the three groups of teen participants displayed no differences in scores on reading, spelling, and nonverbal intelligence tests.

Intriguingly, school records for the teens with bipolar disorder show that their math grades dropped noticeably beginning about 1 year before their psychiatric condition was diagnosed, says Dalhousie psychiatrist Stanley P. Kutcher, a study coauthor. The onset of math troubles long before exposure to psychoactive medication underscores Kutcher’s suspicion that brain changes associated with bipolar illness disturb math reasoning.

Previous research hadn’t looked for any math-related brain regions that may be affected by bipolar disorder. Preliminary brain-scan studies at Dalhousie suggest that teens with this condition have smaller tissue volumes in a frontal-brain area that contributes to math calculations, Kutcher says.

The unexpected link of bipolar disorder to math problems deserves closer scrutiny, comments psychologist David C. Geary of the University of Missouri in Columbia. “I’d be skeptical of this finding until it’s replicated in more studies,” says Geary, who studies the causes of various math deficits.


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Bruce Bower

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

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