Neural Disorders: Advances and Challenges In
this
n
Addiction
n
Alzheimer’s Disease
n
Amyotrophic Lateral Sclerosis
n
Anxiety Disorders
n Attention
36
Chapter —
Addiction Drug abuse is one of the nation’s most serious health problems. Indeed, 9 percent of Americans, more than 22 million people, abuse drugs on a regular basis. Recent estimates show that the abuse
Deficit Hyperactivity Disorder
of drugs, including alcohol and nicotine, costs the nation more than $276 billion each year. If continued long enough, drug abuse — often defined as harmful drug use — can eventually alter the very structure and chemical makeup of the brain, producing a true brain disorder. This disorder is called drug addiction or drug dependence. Drug addiction is characterized by a pathological desire for drugs, such that drugseeking and drug-taking behaviors occupy an inordinate amount of
n
Autism
n
Bipolar Disorder
n
Brain Tumors
and terminating use, despite a stated desire to do so.
n
Down Syndrome
reasons, one of which is that most drugs of abuse produce feelings of
n
Dyslexia
n
Huntington’s Disease
activating a specific network of neurons called the brain reward sys-
n
Major Depression
ing that helps us to stay alive. It evolved to mediate the pleasurable
n
Multiple Sclerosis
are hungry or drinking when we are thirsty. Indeed, when a reward
n
Neurological AIDS
n
Neurological Trauma
n
Pain
abuse affect neurons to exert their influence. Abused drugs alter the
n
Parkinson’s Disease
Some drugs mimic neurotransmitters, whereas others block them.
n
Schizophrenia
vated. Ultimately, in all cases, the brain reward system is activated
n
Seizures and Epilepsy
n
Stroke
n
Tourette Syndrome
Brain Facts |
an individual’s time and thoughts, at the expense of other activities, and these behaviors persist despite many adverse consequences. Addiction is also characterized by difficulty controlling frequency of use People initially experiment with drugs for many different pleasure or remove feelings of stress and emotional pain. Neuroscientists have found that almost all abused drugs produce pleasure by tem. The circuit is normally involved in an important type of learnand motivating effects of natural rewards, such as eating when we produces feelings of pleasure, we learn to repeat the actions that got us the reward in the first place. Drugs can activate this same system and therefore can also promote continued drug use. Neuroscientists have learned a great deal about how drugs of ways neurotransmitters carry their messages from neuron to neuron. Still others alter the way neurotransmitters are released or inactiinappropriately because drugs alter the chemical messages sent among neurons in this circuit. Finally, neuroscientists have learned that addiction requires more than the activation of the brain reward system. Over the past
neural disorders: advances and challenges
20 years or so, research has indicated that the drugs themselves change the brain of susceptible individuals in complex ways, leading
Society for Neuroscience