Accumulating evidence points to the interaction of genetic and
environmental influences in the etiology of personality disorders, according
to Glen Gabbard, M.D.
In a lecture at APA's 2004 annual meeting in May, Gabbard discussed
research on antisocial and borderline personality disorders suggesting that
long-held distinctions between mind and brain or between genes and environment
are no longer relevant.
"Personality disorders are best understood and treated without using
either-or dichotomies of brain and mind," he stated."
Environmental influences on gene expression make nature-nurture
distinctions difficult, and psychosocial factors produce biological changes in
the brain. Medication and therapy work synergistically to make changes in the
brain over time. And the language of the mind is necessary for psychotherapy,
but we must recognize that its effect is on the brain."
Gabbard is the Brown Foundation Chair of Psychoanalysis and a professor of
psychiatry at Baylor College of Medicine in Houston. He is also a training and
supervising analyst at the Houston-Galveston Psychoanalytic Institute.
In a long-term follow-up study, research by Avshalom Caspi, Ph.D., and
colleagues published in the August 2, 2002, Science found an
association between gene-environment interaction and development of antisocial
personality disorder. In particular, the research implicates the monoamine
oxidase A (MAOA) gene, which encodes the enzyme that metabolizes
norepinephrine, serotonin, and dopamine, Gabbard explained.
Eight percent of 1,037 children born in Dunedin, New Zealand, were serially
assessed up to age 26, with 96 percent of the cohort still intact at age 26.
Between the ages of 3 and 11 years, 8 percent experienced "severe"
maltreatment, 28 percent experienced "probable" maltreatment, and
64 percent experienced no maltreatment.
Four sources of information were fit together using a common-factor model
to derive a score for antisocial behavior. The four sources were evidence of
conduct disorder using criteria from DSM-IV, convictions for violent
crimes identified via the Australian and New Zealand police, a personality
disposition toward violence measured as part of a psychological assessment at
age 26, and symptoms of antisocial personality disorder ascertained at age 26
by collecting information about the study members from people they nominated
as "someone who knows you well."
Gabbard reported that males in the cohort who had low expression of MAOA
activity and who experienced childhood abuse also had high antisocial scores,
while males with high MAOA activity did not have high antisocial scores even
if they had experienced maltreatment.
"The researchers concluded that there must be a functional
polymorphism in the MAOA gene that moderates the impact of early childhood
maltreatment on the development of antisocial behavior," he said.
Gabbard also reviewed the findings of primate researcher S.J. Soumi, who
identified a group of "cluster B" rhesus monkeys that displayed
the characteristics of borderline and antisocial personality: the monkeys were
impulsive and overtly aggressive, harassed younger monkeys, challenged
dominant males, and made ill-advised leaps in trees that threatened injury to
themselves or others.
He explained that Soumi discovered a correlation between low serotonin
metabolism and aggressive behavior and a tendency to consume alcohol in an
experimental "happy hour" situation.
The way the monkeys were reared was also found to have a moderating
influence. The monkeys that were raised by their mothers were less likely to
develop antisocial characteristics than those raised by peers. And in the
natural environment, the quality of mothering was further associated with the
development of antisocial personality, Gabbard said.
"The inherited propensity to develop patterns of impulsive aggression
and consume alcohol can be modified by early attachment relationships,"
Gabbard said. "Monkeys raised by peers instead of their mothers
consistently showed lower serotonin in their cerebral spinal fluid and more
alcohol consumption, compared with those reared by their own mothers.
"So both nature and nurture are at play in most, if not all,
biobehavioral aspects of impulsive aggression, and the quality of mothering
has a profound effect on gene expression."
Gabbard said the findings have important implications for early
intervention with high-risk children. He cited a report by David Olds and
colleagues in the October 14, 1998, Journal of the American Medical
Association on the impact of home visitation by a nurse on childhood
In that study, mothers who were under age 19, unmarried, or of low
socioeconomic status were randomly assigned to either regular home nurse
visits throughout pregnancy and up to the child's second birthday or to usual
prenatal and well-child care. The nurses focused on three aspects of maternal
function: health-related behaviors, competent care, and maternal personal
The teens whose mothers had received the nurse visits had significantly
lower rates of antisocial behavior than control subjects, lower rates of
substance abuse, and fewer lifetime sex partners, Gabbard said.
"Genes and environment are inextricably connected in the pathogenesis
of antisocial behavior," he concluded. "The heritable
characteristics of the child often evoke certain kinds of parenting. So there
is a complex interaction of the child's genes, the parents' genes, their fit
in the environment, and how they mutually influence each other."
Similarly, Gabbard said, research on borderline personality disorder shows
an association between early childhood trauma and hyperreactivity of the
hypothalamic-pituitary-adrenal (HPA) axis in response to chronic stress. The
HPA axis is the neuroendocrine system that responds to stress and produces
He drew attention to a probable correlation between HPA hyperactivity and
the typical clinical picture presented by borderline patients. "If you
have a hyperactive HPA axis, you are going to have a hypervigilant, anxious
state that is linked to an internal representation of self and others,"
Gabbard said. "You are likely to see others as potential persecutors and
yourself as a victim."
Psychoactive medication and psychotherapy can act synergistically to
reverse the HPA hyperactivity, diminish hypervigilant anxiety, and improve the
therapeutic relationship. In turn, psychotherapy can over time facilitate the
capacity for "mentalization"—the ability to perceive the
mind of others as distinct from one's own and hence to reconsider and reassess
one's own perceptions of reality.
Development of that capacity is frequently arrested during childhood in
borderline patients who have experienced trauma.
"Mentalization depends on a caregiver who treats the child as a
mental agent and ascribes mental status to that child," Gabbard said."
So mentalizing grows directly out of attachment theory. Attachment
security promotes the development of a sense of one's own mind and the
awareness that others have mind, because you see that in a caregiver growing
Brain imaging studies suggest that the neural networks activated during
mentalization are distributed widely throughout the brain, making it difficult
to locate "the mind" in one area of the brain or to reduce
theories of the mind to simple neuroanatomical categories.
But Gabbard said psychotherapy with borderline patients can successfully
change the brain as the patient develops the capacity to mentalize and to
experience—possibly for the first time—a good and loving object in
"Representations of others and self as translated in the transference
occur in neural networks throughout the brain," he said. "The
capacity to see the therapist as helpful creates new neural networks involving
representations of self and others while weakening the old
In this way, Gabbard said, "psychotherapy is a biological