In: Chemistry
Alcohol abuse and dependence
The National Institute on Alcoholism and Alcohol Abuse has a great deal of information on this topic.
Go to their website and present one article to your classmates; give the website, the citation, and a summary of what it says. No article should be repeated.
Alcohol, Violence, and Aggression
Scientists and nonscientists alike have long recognized a two-way
association between alcohol consumption and violent or aggressive
behavior (1). Not only may alcohol consumption promote
aggressiveness, but victimization may lead to excessive alcohol
consumption. Violence may be defined as behavior that intentionally
inflicts, or attempts to inflict, physical harm. Violence falls
within the broader category of aggression, which also includes
behaviors that are threatening, hostile, or damaging in a
nonphysical way (2). This Alcohol Alert explores the association
between alcohol consumption, violence, and aggression and the role
of the brain in regulating these behaviors. Understanding the
nature of these associations is essential to breaking the cycle of
alcohol misuse and violence.
Extent of the Alcohol-Violence Association
Based on published studies, Roizen (3) summarized the percentages
of violent offenders who were drinking at the time of the offense
as follows: up to 86 percent of homicide offenders, 37 percent of
assault offenders, 60 percent of sexual offenders, up to 57 percent
of men and 27 percent of women involved in marital violence, and 13
percent of child abusers. These figures are the upper limits of a
wide range of estimates. In a community-based study, Pernanen (4)
found that 42 percent of violent crimes reported to the police
involved alcohol, although 51 percent of the victims interviewed
believed that their assailants had been drinking.
Alcohol-Violence Relationships
Several models have been proposed to explain the complex
relationships between violence or aggression and alcohol
consumption. To avoid exposing human or animal subjects to
potentially serious injury, research results discussed below are
largely based on experiments on nonphysical aggression. Other
studies involving humans are based on epidemiological surveys or
data obtained from archival or official sources.
Alcohol Misuse Preceding Violence
Direct Effects of Alcohol. Alcohol may encourage aggression or
violence by disrupting normal brain function. According to the
disinhibition hypothesis, for example, alcohol weakens brain
mechanisms that normally restrain impulsive behaviors, including
inappropriate aggression (5). By impairing information processing,
alcohol can also lead a person to misjudge social cues, thereby
overreacting to a perceived threat (6). Simultaneously, a narrowing
of attention may lead to an inaccurate assessment of the future
risks of acting on an immediate violent impulse (7).
Many researchers have explored the relationship of alcohol to
aggression using variations of an experimental approach developed
more than 35 years ago (8,9). In a typical example, a subject
administers electric shocks or other painful stimuli to an unseen
"opponent," ostensibly as part of a competitive task involving
learning and reaction time. Unknown to the subject, the reactions
of the nonexistent opponent are simulated by a computer. Subjects
perform both while sober and after consuming alcohol. In many
studies, subjects exhibited increased aggressiveness (e.g., by
administering stronger shocks) in proportion to increasing alcohol
consumption (10).
These findings suggest that alcohol may facilitate aggressive
behavior. However, subjects rarely increased their aggression
unless they felt threatened or provoked. Moreover, neither
intoxicated nor sober participants administered painful stimuli
when nonaggressive means of communication (e.g., a signal lamp)
were also available (5,9).
These results are consistent with the real-world observation that
intoxication alone does not cause violence (4). The following
subsections explore some mechanisms whereby alcohol's direct
effects may interact with other factors to influence the expression
of aggression.
Social and Cultural Expectancies. Alcohol consumption may promote
aggression because people expect it to (5). For example, research
using real and mock alcoholic beverages shows that people who
believe they have consumed alcohol begin to act more aggressively,
regardless of which beverage they actually consumed (10).
Alcohol-related expectancies that promote male aggressiveness,
combined with the widespread perception of intoxicated women as
sexually receptive and less able to defend themselves, could
account for the association between drinking and date rape
(11).
In addition, a person who intends to engage in a violent act may
drink to bolster his or her courage or in hopes of evading
punishment or censure (12,13). The motive of drinking to avoid
censure is encouraged by the popular view of intoxication as a
"time-out," during which one is not subject to the same rules of
conduct as when sober (14,15).
Violence Preceding Alcohol Misuse
Childhood Victimization. A history of childhood sexual abuse (16)
or neglect (17) is more likely among women with alcohol problems
than among women without alcohol problems. Widom and colleagues
(17) found no relationship between childhood victimization and
subsequent alcohol misuse in men. Even children who only witness
family violence may learn to imitate the roles of aggressors or
victims, setting the stage for alcohol abuse and violence to
persist over generations (18). Finally, obstetric complications
that damage the nervous system at birth, combined with subsequent
parental neglect such as might occur in an alcoholic family, may
predispose one to violence, crime, and other behavioral problems by
age 18 (19,20).
Violent Lifestyles. Violence may precede alcohol misuse in
offenders as well as victims. For example, violent people may be
more likely than nonviolent people to select or encounter social
situations and subcultures that encourage heavy drinking (21). In
summary, violence may contribute to alcohol consumption, which in
turn may perpetuate violence.
Common Causes for Alcohol Misuse and Violence
In many cases, abuse of alcohol and a propensity to violence may
stem from a common cause (22). This cause may be a temperamental
trait, such as a risk-seeking personality, or a social environment
(e.g., delinquent peers or lack of parental supervision) that
encourages or contributes to deviant behavior (21).
Another example of a common cause relates to the frequent
co-occurrence of antisocial personality disorder (ASPD) and
early-onset (i.e., type II) alcoholism (23). ASPD is a psychiatric
disorder characterized by a disregard for the rights of others,
often manifested as a violent or criminal lifestyle. Type II
alcoholism is characterized by high heritability from father to
son; early onset of alcoholism (often during adolescence); and
antisocial, sometimes violent, behavioral traits (24). Type II
alcoholics and persons with ASPD overlap in their tendency to
violence and excessive alcohol consumption and may share a genetic
basis (23).
Spurious Associations
Spurious associations between alcohol consumption and violence may
arise by chance or coincidence, with no direct or common cause. For
example, drinking is a common social activity for many adult
Americans, especially those most likely to commit violent acts.
Therefore, drinking and violence may occur together by chance (5).
In addition, violent criminals who drink heavily are more likely
than less intoxicated offenders to be caught and consequently are
overrepresented in samples of convicts or arrestees (7). Spurious
associations may sometimes be difficult to distinguish from
common-cause associations.
Physiology of Violence
Although individual behavior is shaped in part by the environment,
it is also influenced by biological factors (e.g., hormones) and
ultimately planned and directed by the brain. Individual
differences in brain chemistry may explain the observation that
excessive alcohol consumption may consistently promote aggression
in some persons, but not in others (25). The following subsections
highlight some areas of intensive study.
Serotonin
Serotonin, a chemical messenger in the brain, is thought to
function as a behavioral inhibitor. Thus, decreased serotonin
activity is associated with increased impulsivity and
aggressiveness (26) as well as with early-onset alcoholism among
men (27).
Researchers have developed an animal model that simulates many of
the characteristics of alcoholism in humans. Rhesus macaque monkeys
sometimes consume alcohol in sufficient quantities to become
intoxicated. Macaques with low serotonin activity consume alcohol
at elevated rates (25); these monkeys also demonstrate impaired
impulse control, resulting in excessive and inappropriate
aggression (25,27). This behavior and brain chemistry closely
resemble that of type II alcoholics. Interestingly, among both
macaques and humans, parental neglect leads to early-onset
aggression and excessive alcohol consumption in the offspring,
again correlated with decreased serotonin activity (27).
Although data are inconclusive, the alcohol-violence link may be
mediated by chemical messengers in addition to serotonin, such as
dopamine and norepinephrine (28). There is also considerable
overlap among nerve cell pathways in the brain that regulate
aspects of aggression (29), sexual behavior, and alcohol
consumption (30). These observations suggest a biological basis for
the frequent co-occurrence of alcohol intoxication and sexual
violence.
Testosterone
The steroid hormone testosterone is responsible for the development
of male primary and secondary sexual characteristics. High
testosterone concentrations in criminals have been associated with
violence, suspiciousness, and hostility (31,32). In animal
experiments, alcohol administration increased aggressive behavior
in socially dominant squirrel monkeys, who already exhibited high
levels of aggression and testosterone (33). Alcohol did not,
however, increase aggression in subordinate monkeys, which
exhibited low levels of aggression and testosterone (6).
These findings may shed some light on the life cycle of violence in
humans. In humans, violence occurs largely among adolescent and
young adult males, who tend to have high levels of testosterone
compared with the general population. Young men who exhibit
antisocial behaviors often "burn out" with age, becoming less
aggressive when they reach their forties (34). By that age,
testosterone concentrations are decreasing, while serotonin
concentrations are increasing, both factors that tend to restrain
violent behavior (35).
Conclusion
No one model can account for all individuals or types of violence.
Alcohol apparently may increase the risk of violent behavior only
for certain individuals or subpopulations and only under some
situations and social/cultural influences (4,36).
Although much remains to be learned, research suggests that some
violent behavior may be amenable to treatment and some may be
preventable. One study found decreased levels of marital violence
in couples who completed behavioral marital therapy for alcoholism
and remained sober during followup (37). Results of another study
(7) suggest that a 10-percent increase in the beer tax could reduce
murder by 0.3 percent, rape by 1.32 percent, and robbery by 0.9
percent. Although these results are modest, they indicate a
direction for future research. In addition, preliminary experiments
have identified medications that have the potential to reduce
violent behavior. Such medications include certain anticonvulsants
(e.g., carbamazepine) (38); mood stabilizers (e.g., lithium) (39);
and antidepressants,
especially those that increase serotonin activity (e.g.,
fluoxetine) (40,41). However, these studies either did not
differentiate alcoholic from nonalcoholic subjects or excluded
alcoholics from participation.
Alcohol, Violence, and Aggression--A Commentary by
NIAAA Director Enoch Gordis, M.D.
Both alcohol use and violence are common in our society, and there
are many associations between the two. Understanding the nature of
these associations, including the environmental and biological
antecedents of each and the ways in which they may be related, is
essential to developing effective strategies to prevent
alcohol-related violence as well as other social problems, such as
domestic violence, sexual assault, and childhood abuse and neglect.
Because no area of science stands apart from another, understanding
more about alcohol-related violence also will shed light on
violence in general and produce information that may be useful to
reducing it.
Science has made progress on elucidating the environmental and
biological antecedents of alcohol abuse and alcoholism; less
progress has been made toward understanding the causes of violence.
Understanding the biology of violence will help us to clearly
define the role of the environment in increasing the risk for
violence and increase our understanding of who is at risk for
violent behavior. This understanding also will help us to develop
effective interventions--both social and medical where intended--to
help those whose violence has caused trouble for themselves and
others.
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Full text of this publication is available on NIAAA's World Wide
Web site at http://www.niaaa.nih.gov.