We know that chemicals influence human behavior. With high blood levels of alcohol, some people will commit acts too horrible to contemplate when cold sober. Policemen and emergency medical workers have coped with people so crazed on amphetamines, crack cocaine, or hallucinogens that it is hard to describe such behavior as rational or even "human." The growing array of chemicals that influence human behavior clashes directly with long-standing doctrines woven deeply into the fabric of society. Our moral and legal tradition depends on the central idea that we each are responsible for our acts. Without that responsibility, the moral basis for trial and punishment for crimes is undetermined. However, the desire to make society work--and to take the stern view of individual responsibility--should not lead to denying the powerful but often unexpected effects of prescription drugs on behavior.
An ever growing fraction of the population routinely takes powerful prescription drugs that rearrange the electrochemical circuits through which all human feelings, thought, and behavior flow. A growing ability to identify, stimulate, or block chemical receptors that are involved in behavior has not been accompanied by an adequate grasp of how the whole system works. Most of what is known involves crude extremes. If the brain cells that secrete a chemical neurotransmitter called dopamine are destroyed, the result is a frozen zombie who cannot move muscles voluntarily. However, if dopamine receptors are stimulated with an agonist drug such as LSD, the result is bizarre perceptions and actions. Even less is known about serotonin. Still, we are treated to discourses about the "clean effects" of Prozac, Paxil, and Zoloft because they are seemingly targeted on serotonin receptors in the brain rather than several different neurotransmitters. But the functional purpose af serotonin neuiotransmitters remains largely unknown. In terms of ability to relieve clinical depression, the antidepressants produce similar results regardless of the neurotransmitters they are presumed to affect. It is as though reseachers have learned the function of some of the transistors in a radio but still don't understand why it is playing soft rock music instead of the baseball game. Change the transistor in an unmapped behavioral circuit, and it is not surprising to observe unexpected and unwanted results at least some of the time. In addition to prescription drugs that are intended to alter feeling and behavior, there are hundreds more that produce unintended and unwanted adverse effects on behavior. To get a sense of the scope of effects and the number of drugs implicated, consider this list of adverse effects, culled from the disclosure labels of approved drugs. After each adverse effect, the number of drugs associated with it appears in parentheses:
Unwanted effects on mood and behavior are most common among drugs targeted on receptors in the brain or central nervous system, especially sedatives, tranquilizers, antidepressants, and neuroleptic drugs for severe mental illness. But they are also seen in a wide array of other agents, notably some antibiotics, antihistamines, blood pressure drugs, diet pills, and drugs for asthma and epilepsy. The severity of the effect also spans the entire spectrum. It seems silly for a manufacturer to list "crying" as an adverse effect of several immunizations for infants. At the other extreme, drugs trigger frightening aberrations such as suicide attempts, manic attacks, and outright psychotic and sociopathic behavior. Such behaviors usually require confinement in a mental health facility, the stigma of a major mental illness, and often a prescription for dangerous and powerful neuroleptic drugs that even when working as intended suppress feeling and behavior.
Scanning the list for the adverse effects linked to very large numbers of drugs, an obvious pattern emerges. Drugs frequently depress the central nervous system. So we find 399 listed drugs that may cause asthenia, the medical term that means "depleted vitality." Another 242 have been blamed for outright depression, and an additional 229 are linked to malaise. The opposite effect--overstimulating the system is also common. So the list includes 239 drugs associated with anxiety as an adverse effect, and another 325 that may cause nervousness, 143 associated with agitation, and 111 linked to excitability.
In many cases, people stop taking medication that makes them too excited or too depressed. However, sometimes people don't realize a drug is behind a bout of depression, anxiety, or excitement. Others don't know that sometimes a switch to another drug takes care of the problem. To get some medical benefits--for example, to prevent epileptic seizures, or reduce the most severe paln--many people will tolerate major adverse effects. For example, one woman, overstimulated by her new diet pills, said, "I've still got a couple of rooms to clean, but then what? I feel like I've had WAY too much caffeine." Mostly, the adverse effects stop when she person stops taking the drug.
A third group of drugs may impair memory and thought. Mental confusion can result from 314 drugs, and another 107 cause impaired mental performance. At least 36 drugs are linked to memory impairment, and another 34 list short-term memory loss as an adverse effect. Other drugs may cause black-out spells, altered mental status, impaired motor skills, incoherent speech. These effects can be more treacherous because sometimes the individual remains unaware of the impairment, let alone the cause.
Our greatest concern should be reserved for the drugs that may cause behavior so extreme that long-standing relationships are destroyed or violence occurs. These more severe reported drug effects include rage, aggression, violent behavior, mania, psychotic episodes, and thoughts of, or attempts at, suicide. At least 226 drugs list an association with these severe effects. The true cost of these terrible episodes is that individuals are often unable to resume, unchanged, the lives they had before.
