HASPI Medical Anatomy & Physiology
Drug Abuse & Addiction

Drug addiction is a mental and/or physical dependency. The drug may be illegal, prescribed, over the-counter, or a substance that does not have any actual medical use. While the initial decision to take a drug is voluntary, the changes that result in the brain from drug use create a compulsive chronic need for the drug. Drug abuse and addiction cost the United States more than $600 billion annually in healthcare and crime-related costs. More than $190 billion can be contributed to illicit drugs, $190 billion to tobacco use, and more than $250 billion to alcohol abuse. While the direct cost is easily measurable and substantial, the influence of drug abuse on public safety, employment, family disintegration, violence, and domestic abuse has a much greater negative impact on society.
The Impact of Drugs on the Brain
The majority of drugs have a direct or indirect effect on the neurons in the brain, specifically on neurotransmitters and receptors at the synapse. Drugs can cause disruption in the brain’s normal communication methods, primarily by stimulation or inhibition of receptors, or by mimicking a neurotransmitter. The neural pathway associated with “reward” is most commonly affected. As the brain is regularly exposed to a drug, it will react by producing less of the neurotransmitter involved by the specific drug, which can lead to tolerance. The user can eventually succumb to abuse and addiction, as he/she have to take increasingly more of the drug to feel “normal.”Data courtesy of the NIH National Institute on Drug Abuse
Drug Schedules & Categories
Drugs can come in a wide variety of forms, and are placed in five schedules, according to regulations created by the Food & Drug Administration (FDA) as part of the Controlled Substance Act. Table 1 summarizes the requirements and examples of drugs placed in each schedule according to the FDA.
Table 1. FDA Drug Schedules
Schedule I
Schedule II
Schedule III
Schedule IV
Schedule V
High potential for
abuse, no currently accepted medical
use, and a lack of
accepted safety for use under medical supervision.
▪ LSD
▪ MDMA (Ecstasy) ▪ Marijuana
▪ Heroine
▪ Methaqualone
▪ Phencyclidine
(PCP)
▪ Hallucinogenic
mushrooms
High potential for
abuse, has a currently accepted medical use, and abuse may lead to severe
psychological or
physical dependence.
▪ Morphine
▪ Cocaine
▪ Opium
▪ Methamphetamine
Has a potent

Question

HASPI Medical Anatomy & Physiology 
Drug Abuse & Addiction


Drug addiction is a mental and/or physical dependency. The drug may be illegal, prescribed, over the-counter, or a substance that does not have any actual medical use. While the initial decision to  take a drug is voluntary, the changes that result in the brain from drug use create a compulsive  chronic need for the drug. Drug abuse and addiction cost the United States more than $600 billion  annually in healthcare and crime-related costs. More than $190 billion can be contributed to illicit  drugs, $190 billion to tobacco use, and more than $250 billion to alcohol abuse. While the direct cost  is easily measurable and substantial, the influence of drug abuse on public safety, employment,  family disintegration, violence, and domestic abuse has a much greater negative impact on society. 
The Impact of Drugs on the Brain 
The majority of drugs have a direct or indirect effect on the neurons in the brain, specifically on  neurotransmitters and receptors at the synapse. Drugs can cause disruption in the brain’s normal  communication methods, primarily by stimulation or inhibition of receptors, or by mimicking a  neurotransmitter. The neural pathway associated with “reward” is most commonly affected. As the  brain is regularly exposed to a drug, it will react by producing less of the neurotransmitter involved by  the specific drug, which can lead to tolerance. The user can eventually succumb to abuse and addiction, as he/she have to take increasingly more of the drug to feel “normal.”Data courtesy of the NIH National Institute on Drug Abuse 
Drug Schedules & Categories 
Drugs can come in a wide variety of forms, and are placed in five schedules, according to regulations  created by the Food & Drug Administration (FDA) as part of the Controlled Substance Act. Table 1  summarizes the requirements and examples of drugs placed in each schedule according to the FDA. 
Table 1. FDA Drug Schedules
Schedule I 
Schedule II 
Schedule III 
Schedule IV 
Schedule V
High potential for  
abuse, no currently  accepted medical  
use, and a lack of  
accepted safety for  use under medical  supervision. 
▪ LSD 
▪ MDMA (Ecstasy) ▪ Marijuana 
▪ Heroine 
▪ Methaqualone 
▪ Phencyclidine  
(PCP) 
▪ Hallucinogenic  
mushrooms
High potential for  
abuse, has a currently  accepted medical use,  and abuse may lead  to severe  
psychological or  
physical dependence. 
▪ Morphine 
▪ Cocaine 
▪ Opium 
▪ Methamphetamine
Has a potent