Amphetamine and methamphetamine are chemically similar substances that stimulate the central nervous system (brain and spinal cord) and produce a variety of effects that include excitation and euphoria.
Amphetamine is the active ingredient in a number of different medications (including Adderall and Dexedrine), while methamphetamine is an illegal street drug.
People who attempt to drive while under the influence of amphetamine or methamphetamine typically experience a number of impairments that seriously reduce their ability to safely control a motor vehicle. These impairments lead to increased risks for involvement in various types of driving incidents and accidents.
As their names imply, amphetamine and methamphetamine are closely related. In fact, when methamphetamine is used/abused, the natural chemical breakdown process inside the body eventually turns it into amphetamine. Both amphetamine and methamphetamine achieve their drug effects in new users by increasing brain levels of three different hormones-dopamine, serotonin, and norepinephrine-that play a dual role by acting as neurotransmitters and relaying chemical signals between nerve cells in the brain known as neurons. Heightened levels of dopamine produce the euphoric effects associated with amphetamine and methamphetamine use. Heightened levels of serotonin improve mood and bring a sense of well-being. Heightened levels of norepinephrine trigger the body’s natural “fight-or-flight” response and produce increases in alertness and resistance to fatigue, as well as decreases in normal appetite.
Unfortunately, alteration of the levels of dopamine, serotonin and norepinephrine can also produce profoundly negative results, especially when amphetamine and methamphetamine are used in high doses. For instance, alteration of dopamine levels can produce distortions in normal perception and symptoms of psychosis, such as hallucinations, delusions, highly disordered thinking, and extreme confusion. Alterations in dopamine levels can also produce symptoms of psychosis. Alterations in norepinephrine levels can produce anxiety, as well as dangerous overstimulation of the cardiovascular system.
Over time, regular abusers of amphetamine and methamphetamine commonly experience a decrease in their dopamine and serotonin production. This decrease can produce ongoing effects that include increases in impulsive behavior, a marked tendency toward aggression and violence, depression, anxiety and a state of mental and emotional unease known as dysphoria, which can be viewed as the rough opposite of euphoria. People frequently become addicted to amphetamine or methamphetamine when they repeatedly attempt to reproduce the euphoric effects of these drugs, and simultaneously attempt to avoid feeling the dysphoric effects brought on by drug-related changes in basic brain chemistry.
Effects on task performance
According to the National Highway Traffic Safety Administration (NHTSA), relatively low doses of amphetamine and methamphetamine (roughly 10-30 mg) have effects on task performance that include improved processing of mental information, reduced levels of fatigue, an improved ability to accurately estimate the passing of time, an improved ability to react rapidly to changing physical circumstances, and self-reported increases in overall alertness. In addition, relatively low doses of these drugs significantly increase amphetamine- and methamphetamine-intoxicated individuals’ willingness to engage in high-risk behaviors. Higher doses of amphetamine and methamphetamine produce effects on task performance that include a reduced ability to focus or remain attentive, slowed reflexes, loss of normal balance and body control, mental agitation, restlessness, a reduced ability to follow instructions or directions, a decreased ability to react rapidly to changing circumstances, and a decreased ability to accurately estimate the passage of time.
Contributions to driving impairment
Drivers under the influence of amphetamine or methamphetamine frequently exhibit impaired behaviors that include driving at a high rate of speed, swerving from side to side, maintaining an unsafe distance from other vehicles, failing to react to changing traffic circumstances, failing to stop appropriately at stoplights or stop signs, and engaging in vehicular maneuvers that carry a high risk for triggering an accident. People stopped for driving while intoxicated on either of these two drugs commonly exhibit symptoms and behaviors that include inability to speak coherently, inability to maintain an upright body posture, and a tendency toward aggression and violence.
Statistics and considerations
It takes hours for the body to break down and completely eliminate amphetamine and methamphetamine. According to a study published in 2006 in Accident; Analysis and Prevention, roughly 75% of drivers with breakdown products of amphetamine or methamphetamine in their systems who are stopped by police show clear signs of driving impairment. The authors of this study noted that, while low doses of amphetamine and methamphetamine have a reputation for improving task performance in a laboratory setting, in the real world, even small amounts of these drugs can seriously degrade driving performance. This fact may be related to the tendency for people using low doses of amphetamine/methamphetamine to engage in high-risk behaviors while driving.