Exploring the Brain Chemistry of People at Risk for Alcohol Disorders

  • Children of alcoholics (COAs) tend to exhibit attention deficit disorder, hyperactive tendencies, rule breaking, and poor response to discipline.
  • Adult COAs tend to exhibit poor impulse control, antisocial tendencies and sensation seeking.
  • A new study has found that young adult COAs have a different emotional response to environmental cues than do individuals without a family history of alcoholism.
  • These findings may demonstrate underlying differences in brain chemistry and physiology.

Research overwhelmingly indicates that children of alcoholics are more likely to develop significant alcohol problems, such as abuse or dependence, than will children of non-alcoholics. It is also well documented that both genetic and environmental factors contribute to this increased risk. Genetic or inherited factors include biologically rooted behavioral tendencies and self-regulation. For example, individuals with a family history of alcoholism tend to exhibit poor impulse control, antisocial tendencies and sensation seeking. A study in the April issue of Alcoholism: Clinical & Experimental Research has found that individuals with a positive history of alcoholism have a different emotional response to environmental cues than do individuals with a negative family history of alcoholism.

"Persons at high risk for alcoholism, because they have a father with alcohol abuse or dependence in his past," explained William R. Lovallo, Director of the Behavioral Sciences Laboratories at the Veterans Affairs Medical Center, Oklahoma City and corresponding author for the study, "are different from low-risk persons in how they respond to the emotional content of events in their immediate environment. This difference in emotional responsiveness may tell us something about how the increased risk of alcoholism is related to the functioning of the brain systems that allow us to experience events and respond to them."

Lovallo noted that alcohol or other substance abusers tend to have specific kinds of behavior when they are children. "There is a higher prevalence of attention deficit disorder, hyperactive tendencies, rule breaking, and poor response to discipline," he said, "than in a comparable group of non-abusers. The particular functions have to do with regulation of attention, movement control, and emotional reactions to people and events. A key feature of antisocial personality disorder, seen during adulthood, and of conduct disorder, its childhood predecessor, is a lack of normal response to aversive events. This is manifested by the inability of such children and adults to respond normally to parental corrections and even to corporal punishment. This lack of response to social censure and physical punishment is quite striking since normal children and adults crave approval and will modify their behavior to obtain it. So, there is an emerging set of ideas that the systems embedded in the brain that respond to emotionally significant events may be lacking in some individuals, evidenced by their inability to respond to external events. Although we might consider such purely psychological processes as empathy, social competence, and rule abiding to be functional and not related to underlying physiological processes, the approach we are taking is that even these sorts of behaviors have an underlying basis in the chemistry and physiology of the brain."

A "startle response" or "startle reflex" is when people jump at the sound of a loud, unexpected noise. The reflex is generally dependent on cues: it can be made stronger by viewing negative photographs, such as traffic accident victims; it can be made weaker by positive photographs, such as happy babies and favorite foods. The part of the brain that causes change in the startle reflex is the amygdala. The amygdala is also involved in forming emotions in response to things an individual sees and hears. For example, humans whose amygdalas are damaged tend to be deficient in their emotional reactivity. In short, the amygdala is involved in both the alteration of the startle reflex and in more general emotional functioning. The amygdala is controlled in part by the brain's dopamine system, the same system that responds to alcohol and also produces feelings of pleasure when good things happen. Scientists believe the ability of the amygdala to react to emotional events is associated with how much dopamine is being released by specialized dopamine neurons.

For this study, researchers examined the emotional response of 60 healthy young adults, 18 to 27 years of age, to environmental cues. The participants were divided into two groups of 30 (15 males, 15 females): those with a positive paternal history of alcoholism (FH+), and those without (FH-). All participants were interviewed and completed self-reports in order to create a personal, psychological and alcohol-history profile, and had their eye-blink electromyogram (EMG) activity to acoustic startle probes measured while viewing 36 color photographs. Following the latter procedure, participants rated the photographs as pleasant, neutral or unpleasant.

The FH- group showed a normal linear increase in the eye-blink EMG component of the startle reflex, with response strength increasing from the pleasant to neutral to unpleasant photographs. In contrast, the FH+ group did not show the typical increase of eye-blink EMG to the unpleasant photographs.

"The findings suggest that FH+ individuals may have a deficit in their aversive motivational system or AMS that might lead them not to learn to moderate their drinking so that they avoid the negative consequences of drinking," said Peter R. Finn, associate professor of psychology at Indiana University. "The theoretical rationale runs something like this: an under-responsiveness to the aversive photographs is associated with a relative weakness, or reduced strength, of the AMS, which is critical for learning to avoid unpleasant experiences and behavior that leads to unpleasant experiences or negative outcomes. Excessive alcohol use is associated with a variety of negative outcomes, such as problems with the law, in relationships, at work, and with physical and psychological health."

"All drugs stimulate the brain's dopamine system," added Lovallo. "A simple version of the story is that dopamine outputs to the amygdala may affect how it tells the rest of our brain to respond to the positive and negative pictures we used. If this speculation is true, it gives us additional insights into the way that the brain's dopamine system is altered in persons at high risk for alcoholism. For example, if this system is not working properly, a release of dopamine following alcohol intake may result in greater positive feelings for such persons. It may act to improve or stabilize their mood, at least early in the process of becoming dependent. So, the brain alterations we are tapping in this study may tell us about how mood differences are related to the elevated risk for future alcoholism that is present in offspring of alcoholics."

"It is critical that researchers find out if this pattern of reduced responsiveness to aversive stimuli actually predicts the development of alcohol problems," said Finn. "One approach is to see whether young individuals such as young teens who show hyporesponsiveness are more likely to develop alcohol problems compared with those who do not show this trait. In addition, it is important to determine whether it is specifically parental alcoholism that is associated with hyporesponsiveness to aversive stimulation and not some other characteristic of the parent. For instance, alcoholic parents often suffer from depression or have antisocial personality disorder, both of which are associated with disturbances in emotion-modulated startle."

Lovallo and his colleagues next plan to examine a larger group of high-risk young adults using the same startle reflex method, as well as other ways to probe emotional reactivity, such as stress hormone responses to socially challenging public-speaking tasks. "By gaining experience in working with such groups," said Lovallo, "we can start a long-term study of persons at risk before they have begun drinking excessively. We can then perform follow-up studies to see who does and who does not show a tendency to drink heavily."

Funding for this Addiction Science Made Easy project is provided by the Addiction Technology Transfer Center National Office, under the cooperative agreement from the Center for Substance Abuse Treatment of SAMHSA.

Articles were written based on the following published research:

Miranda, R., Meyerson, L.A., Buchanan, T.W., & Lovallo, W.R. (2002, April). Altered emotion-modulated startle in young adults with a family history of alcoholism. Alcoholism: Clinical & Experimental Research, 26(4), 441.

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