Methamphetamine and driving impairment.

Following a review of the effects of methamphetamine on human performance, actual driving and behavior were evaluated in 28 cases in which drivers arrested or killed in traffic accidents had tested positive for methamphetamine. The circumstances surrounding the arrest or accident were examined, together with any observations by the arresting officer regarding behavioral irregularities. The investigators also made a determination of culpability. Most of the arrests resulted from accidents in which the driver was determined to be culpable. Typical driving behaviors included drifting out of the lane of travel, erratic driving, weaving, speeding, drifting off the road, and high speed collisions. Behavioral manifestations of methamphetamine use in arrestees included rapid or confused speech, rapid pulse, agitation, paranoia, dilated pupils, violet or aggressive attitude. Combined alcohol and methamphetamine use was uncommon, however use of marijuana was evident in about one third of the cases. In addition to impairing judgment and increasing risk taking, the effects of withdrawal from methamphetamine use including fatigue, hypersomnnolence, and depression are likely contributors to many of these accidents. A consideration of the literature and the cases discussed here, leads to the conclusion that methamphetamine at any concentration is likely to produce symptoms that are inconsistent with safe driving.