Direct evidence concerning the role of amphetamines in highway accidents is scant. Laboratory data indicate that most of the basic skills involved in driving are not adversely affected by amphetamine dosages within the normal clinical range, and may in fact be slightly enhanced. Such enhancement is generally greater in sleep-deprived subjects, but is not limited to states of sleep deprivation. Enhancement has also been reported in subjects whose skills have been degraded by alcohol, although results have not been consistent across performance measures. Although there is some evidence that amphetamines induce overconfidence or increase risk acceptance, the effects reported have been neither so strong nor so consistent as to justify much of the apparent concern. Excessive or prolonged "spree" use is widely recognized to result in abnormal psychological states that are incompatible with safe driving performance, and known amphetamine abusers have been found to be involved in disproportionate numbers of highway accidents. Available epidemiological statistics are inadequate to establish how often such excessive consumption is associated with driving, or in any other way to quantify the total contribution of amphetamine abuse to traffic accidents.
BACKGROUND
Drugs of the amphetamine family are classified, pharmacologically, as sympathomimetic amines. They produce effects on vasomotor functions that are grossly similar to those resulting from stimulation of the sympathetic division of the autonomic nervous system, or from the release of epinephrine (adrenalin) into the blood stream from the adrenal medulla. Among the effects of clinical interest is nasal decongestion, for which the amphetamine (Benzedrine) inhaler enjoyed wide over-the-counter sales in the 1930s and 1940s. However, amphetamine is also a powerful stimulant of the central nervous system, as are its isomer dexamphetamine and the N-methyl substituted derivative, methamphetamine. Such "central" effects include general activation, appetite depression and euphoria when taken in sufficient dosage. These properties were responsible for a gradual increase in "abuse" of amphetamines by those seeking a temporary mood elevation, or who wished to delay the normal onset of sleep, as in prolonged operation of motor vehicles. Such abuses were responsible for discontinuation of over-the counter "Benzedrine" sales and for continual increases in stringency of the federal regulation of amphetamine production and distribution. Currently, amphetamine and most of its relatives are placed on Schedule II of the 1968 Drug Control Act, a listing that includes the most abuse-prone substances for which legitimate medical purposes are recognized in the U.S.A. (e.g. morphine). Its recognized medical uses are largely limited to narcolepsy, childhood hyperkinesis, and short-term appetite control.
EPIDEMIOLOGICAL DATA