BLACK AMERICANS are one third again as likely as whites to have hypertension, say 1988 statistics compiled by the American Heart Association. Now, according to results of a Tennessee study presented at the annual meeting of the Society of Behavioral Medicine, there are indications that black children's cardiovascular systems are more likely to exhibit an enhanced reactivity to stress—a phenomenon that several studies have linked to the subsequent development of hypertension (JAMA 1986;256:11-17).
It is not yet certain whether this reactivity is simply a marker of some other factor that predisposes to hypertension or is directly involved in its cause. Furthermore, studies involving measures of cardiovascular reactivity have used widely varying methods to assess the phenomenon, from cold pressor tests to backward-writing tasks. In the cold pressor test, the subject immerses the right hand and forearm into ice water for one minute. The latter test theoretically induces stress by forcing