Prescription drugs change the chemistry of the brain. The brain is made up of about 100 billion neurons, also known as nerve cells. Neurons communicate with each other by using chemical messengers called neurotransmitters. There are many types of neurotransmitters, and each one carries a specific message. Neurotransmitters deliver their messages by attaching to special places on nerve cells called receptors. Prescription drugs act by mimicking certain neurotransmitters. On the next page, we will learn more about specific types of prescription drugs that can be dangerous when abused.