Psychosomatic factors in borderline hypertensive subjects and offspring of hypertensive parents. Psychosomatic factors, sympathoneural and sympathoadrenal as well as cardiovascular mechanisms, were studied in 24 patients 18-24 years of age with borderline hypertension, 50 age-matched normotensive offspring of hypertensive parents, and 49 controls with no family history of hypertension. They were compared by projective and questionnaire-based psychological tests and their circulatory and neurohormonal reactivity to mental (Stroop color-word conflict test and arithmetic test) and physical stressors (orthostasis and bicycle ergometry test) were measured. Borderline hypertensive subjects externalized aggression less (p less than 0.05) but internalized it more (p less than 0.05) and were more submissive (p less than 0.05) when compared with controls. Offspring of hypertensive parents showed a similar but weaker pattern. Both risk groups reported more positive interactions with their parents (genetic risk subjects versus controls, p less than 0.05; borderline hypertensive patients versus controls, p = 0.08) and had higher state-anxiety levels (p less than 0.05). There were more subjective symptoms of beta-adrenergic receptor-mediated functions (e.g., tachycardia, tremor) in borderline hypertensive subjects and offspring of hypertensive parents, elevated heart rates (analysis of repeated measures, p less than 0.001), and enhanced plasma norepinephrine concentrations (p less than 0.05) when compared with controls. These findings in subjects at risk for the development of hypertension suggest that psychosomatic factors and sympathetic overactivity are involved in the early phase of hypertension. 