The Frontiers of Pharmacology

The idea of a biology of temperament -- that is, the innate tendencies toward how someone relates to their environment -- is not a new one. We have now, however, arrived at a point in our understanding of the brain that we can begin to explore the underlying mechanisms that contribute to specific temperamental styles. New tools to probe brain chemicals, as well as new imaging techniques to actually visualize how the brain works, allow scientists to get a clearer idea of how individual differences in brain functioning might contribute to differences in personality.

While temperament may be present at birth, personality develops, through ongoing experience, over the course of a lifetime. Personality is a complex constellation of traits, coping strategies, and defenses against seemingly built-in vulnerabilities. Some people struggle through life, for example, because they fly off the handle too easily; others seem to be born already armed with a set of defensive tools to combat life's difficulties.

In our laboratory, we try to identify and evaluate certain traits to discover how they relate to personality and its related disorders and discomforts.

Frank was a middle-aged man who came to our evaluation program because his boss suggested he seek psychiatric treatment. He was a good accountant but nevertheless was always passed over for promotion because he couldn't supervise other employees. Quiet and conservative, he rarely made eye contact with colleagues and, when faced with pressure or deadlines, he would perceive coworkers' questions as intrusive and become angry and abusive. He generally felt misunderstood by others and considered himself a loner.

When he completed the testing program, I reviewed some of the findings with Frank. I explained to him that his ability to organize information seemed to decline rapidly when he was under stress and became upset. At this point he would lash out at what he imagined was the source of his distress, often finding meanings in events or comments where they were not warranted.

In the course of our discussion, Frank began to feel that some of his angry behavior and peculiarities were finally being understood by someone. He also latched on to the idea that a chemical imbalance in his brain may have caused his problem. I explained that much of our research was still preliminary, but that, with proper medication, the disorganization he experienced under stress (which was causing many of his problems with people) might be alleviated.

THREE KEY TRAITS

While a knowledge of the biology of the brain and its relation to personality will not allow us to predict an individual's behavior, it may offer us a vocabulary to understand why some people are more prone to outbursts of anger, for instance, while others are painfully shy, and fearful of social contact.

In addition, understanding the biologic vulnerabilities to traits such as impulsivity or irritability may also help physicians to identify medications that will reduce these troublesome tendencies. It should also help them find more adaptive solutions to their life dilemmas.

In our program, we focus on three personality traits -- impulsivity, emotional reactivity (which can also be thought of as sensitivity or irritability), and eccentricity -- in people whose disturbed thoughts, feelings, and/or behaviors are severe enough that they result in problems at work or in their relationships. In their extreme form of expression -- when they are not episodic but characteristic of how someone relates to the world around them -- these traits are analogous to more serious mental disorders: Impulsivity, for example, is related to kleptomania; emotional reactivity to depression; and eccentricity to schizophrenia.

In order to better define the biologic bases of certain personality disorders, we have focused on individual differences in neurotransmitter systems and their relation to these key traits.

The first trait, impulsivity (a tendency to act aggressively rather than reflect), rather consistently appears to relate to brain chemistry. Abnormalities in one of the brain's messenger systems -- the release and uptake of serotonin (a neurotransmitter involved in aggression and ambition, among other functions) -- have been found in people who get into trouble because they act without thinking. They may be irritable and get into fights; experience stormy, unstable relationships; or have trouble with alcohol and drugs.

Drugs such as fluoxetine (Prozac), which prolong the effect of serotonin by slowing its reuptake in the brain, might be beneficial in improving not only mood but also the tendency toward impulsive, aggressive, or self-destructive behavior.