The effects of four antihypertensive agents on the Stroop colour-word test in normal male volunteer subjects.

Sixty healthy male volunteers were randomly assigned to one of six treatment groups on a double-blind basis: 1. Atenolol = 50 mg t.d.s. 2. Methyl dopa = 250 mg t.d.s. 3. Propanolol = 40 mg t.d.s. 4. Reserpine = 0.2 mg t.d.s. 5. Placebo. 6. Control = no tablets. Tests were carried out before treatment, 2 h after the first dose, after seven doses, and after 21 doses. Subjects performance on the Stroop Colour-Word Test was assessed in terms of (a) word reading speed and (b) an 'interference' score based on the difference between the incongruous colour word and colour card reading speed. No evidience was found of central effects of the beta-blockers, but personality X drug interactions were found, particularly in the reserpine group.