Placebo-controlled biofeedback blood pressure effect in hypertensive humans.

The role of biofeedback in blood pressure control remains ill-defined because of nonspecific (placebo) effects, small study numbers, and the technical limitations of continuous pressure feedback. Clarification of its potential is awaited by those seeking a nonpharmacological approach to blood pressure control. This study examines the capability for systolic pressure lowering of 5 mm Hg or more using continuous pressure feedback in a statistical sample of untreated, well-characterized, mildly hypertensive individuals. Subjects were randomized in a double-blind study to active or placebo biofeedback. Placebo consisted of a modified contingency approach, using a partial disguise based on a digital high pass filter with 15 elements. Blood pressure-lowering capability was assessed during two laboratory sessions. Continuous visual feedback resulted in 11 of 28 subjects on active treatment and 12 of 28 on placebo treatment lowering their systolic pressure by 5 mm Hg or more (11 +/- 5.6 and 12 +/- 8.4 mm Hg, respectively; P = NS). Prestudy pressure was well-matched (153 +/- 9/97 +/- 4 and 154 +/- 8/98 +/- 4 mm Hg, respectively). An initial small difference in diurnal profile did not change. These findings indicate that among mildly hypertensive individuals, almost half can lower systolic pressure at will for short periods. This capability is independent of the real or placebo nature of the feedback signal. We conclude that there is no specific short-term biofeedback pressure-lowering capability in hypertensive individuals. Further exploration is needed to determine whether specific components of the placebo effect can be delineated, whether personality characteristics influence the response, and whether further biofeedback training can alter the outcome.

Depressed lymphocyte function after bereavement.

During 1975 twenty-six bereaved spouses took part in a detailed prospective investigation of the effects of severe stress on the immune system. T and B cell numbers and function, and hormone concentrations were studied approximately 2 weeks after bereavement and 6 weeks thereafter. The response to phytohaemagglutinin was significantly depressed in the bereaved group on the second occasion, as was the response to concanavalin A at 6 weeks. There was no difference in T and B cell numbers, protein concentrations, the presence of autoantibodies and delayed hypersensitivity, and in cortisol, prolactin, growth hormone, and thyroid hormone assays between the bereaved group and the controls. This is the first time severe psychological stress has been shown to produce a measurable abnormality in immune function which is not obviously caused by hormonal changes.