Final answer:
Marijuana and amphetamines impair driving by affecting coordination, judgment, and reactions, and increasing risk-taking and overconfidence. Amphetamines at therapeutic doses help with ADHD, but high doses impair cognitive functions, compromising driving safety.
Step-by-step explanation:
The use of marijuana and amphetamine has significant effects on driving abilities. Marijuana can impair motor coordination, judgment, and reaction times, which are critical skills needed for safe driving. Similarly, the use of amphetamines, which include drugs like methamphetamine and MDMA ('ecstasy' or 'molly'), can lead to increased risk-taking, overconfidence, and altered perception, also reducing driving safety. With the psychoactive effects on the brain altering mood, perception, thinking, and behavior, both legal and illegal drug use can sometimes lead to addiction. Moreover, while prescribed in therapeutic doses, amphetamines can help with conditions like ADHD, excessive use or recreational doses are associated with serious side effects and degrade various cognitive functions, which can be detrimental to driving capabilities.