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While many drugs speed up or depress the central nervous system, there is a class of drugs that distorts how we feel, hear, see, smell, taste, and think. Called s because users often hallucinate, or experience nonexistent sensations, these drugs are also known as ....

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.... a plant belonging to the hemp family . The active principle responsible for the drug's effects is tetrahydrocannabinol (THC), obtained from the amber-colored resin of the flowering tops and leaves of the plant. Hashish is also made from this resin. Of all drugs, synthetic and natural, the most powerful is LSD, or lysergic acid diethylamide. Twenty micrograms, an almost infinitesimal amount, is sufficient to produce a hallucinogenic effect; just 3 pounds (1.4 kilograms) could induce a reaction in all the inhabitants of New York City and London. This extraordinary potency makes LSD especially dangerous since it is usually impossible to determine how ....