Evidence indicating that corticosteroid therapy may adversely affect attention and memory in asthmatic subjects is reviewed. The potential impact of corticosteroid dosage levels (high versus low) and treatment regimens (daily versus alternate day) on attention and memory is discussed. Findings indicate that the suppression of ACTH by corticosteroids may have different effects on attention and memory as a function of the sex of the asthmatic patient. The need to establish what the effects of theophylline-induced reductions of cerebral blood flow and cerebral oxygen tension are on higher cognitive processes are outlined. The importance of establishing whether or not medications commonly used for the treatment of asthma create deficits of memory or attention that interfere with medical compliance is emphasized.

Asthma results from variable and often sudden changes in airway smooth muscle tone. Allergy is not an essential component of the asthmatic response; however, mediator release plays an important role in the human asthmatic response. Histamine may act directly to cause bronchoconstriction by stimulating the H1-receptor on airway smooth muscle or indirectly by stimulation of afferent vagal fibers in airways. Histamine may also act locally on airways to augment cholinergic and, possibly, alpha-adrenergic constrictor effects, or to antagonize beta-adrenergic relaxation of airway smooth muscle. Cholinergic neural output promotes bronchoconstriction in non-atopic asthma, but parasympathetic reflexes are not a major component of human bronchial responses to inhaled allergen. The physiologic significance of the sympathetic nervous system in relaxing airway smooth muscle is incompletely defined. Recent studies suggest that direct sympathetic innervation of airways is relatively unimportant and that purinergic fibers may be the predominant inhibitory neurons in human airways. Investigations focusing on intracellular calcium metabolism in airway smooth muscle have implicated the adenyl cyclase-cyclic adenosine monophosphate system in the regulation of bronchomotor tone. Cyclic nucleotides may modulate but do not mediate respiratory muscle contraction, and their precise role in regulating bronchomotor tone remains uncertain.