New markers for type A behavior: pupil size and platelet epinephrine.
This study tested the hypothesis that the Type A behavior pattern and its components are associated with increased activity of the sympathetic nervous system. To do this, we employed two new markers of sympathetic tone--pupil size and platelet catecholamine content. Thirty-three healthy males were blindly rated for Type A behavior and verbal stylistic components by Structured Interview. Adrenergic tone to the pupils was assessed from pupil diameter recorded by infrared television pupillometry, and pupil alpha-adrenergic sensitivity was estimated from mydriatic response to ophthalmic phenylephrine. Platelet epinephrine and norepinephrine contents were assayed because these levels are associated with chronic, long-term circulating catecholamine levels. The results showed Type As had consistently larger pupil diameters than Type Bs (p = 0.03, 0.03, and 0.01). There was no difference in pupillary response to phenylephrine instillation between groups. Platelet epinephrine content was greater in Type A subjects (chi 2 = 4.25, p less than 0.04, t = 1.6, p = 0.06). Only the component of explosiveness was modestly associated with resting pupil size, and no components significantly predicted platelet catecholamines. We conclude that the results of these two new markers of autonomic activity, namely, pupil size and platelet epinephrine, suggest that Type A behavior is characterized by increased sympathetic nervous system tone although we cannot rule out the possibility of decreased activity of the parasympathetic nervous system.
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor.
R H
RH
Schneider
S
S
Julius
G E
GE
Moss
T E
TE
Dielman
A J
AJ
Zweifler
R
R
Karunas
D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D001792:Blood Platelets / Q000032:analysis; D004837:Epinephrine / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D010656:Phenylephrine / Q000494:pharmacology; D011680:Pupil / Q000187:drug effects / Q000502:physiology*; D014434:Type A Personality
D010656:Phenylephrine; D009638:Norepinephrine; D004837:Epinephrine