Not infrequently in clinical medicine, myths develop even before data are available to support the advanced concept. Often these myths become so ingrained that it becomes a most difficult task to extract the fancy from the presumed fact. When the myth involves a therapeutic agent, more frequently, a pharmacological compound, the "factual cloak" surrounding the myth may even creep into the regulatory approval process for that group of agents.
Such a body of "20th-century clinical impressionism" has developed around the β-adrenergic receptor—blocking drugs. It is true that certain patients develop depression while receiving β-blockers; and this risk is said to be greater if the patient originally suffered from mental depression. Other problems ascribed to this class of agents concern exercise intolerance and impaired mental performance. More subtle nonintellectual side effects have occasionally been related to hypertensive patients by transferring side effects from another disease. For example,
See also p 779.