Causes

Various theories have been developed to explain the etiology of personality
disorders. The biological perspective examines the roles of genetics and
brain functioning in the development of personality disorders. Evidence
suggests that the cluster A disorders (paranoid, schizoid, and schizotypal
personality disorders) are more prevalent among first-degree relatives of individuals
suffering from schizophrenia, suggesting a possible genetic commonality
among those disorders.
The underlying symptoms of borderline personality disorder (impulsivity
and emotionality) are inherited. Much research confirms that borderline
patients are more likely to report a childhood family history that included
sexual abuse, domestic violence, and the early loss (either through death or
abandonment) of a parental figure. It is believed that this history may be related
to the later development of borderline personality disorder. According
to Erikson, a sense of basic trust during childhood is an essential component
of normal personality development. Erikson stated that a basic sense of
trust or mistrust in the self and the world develops in the first year of life.
The experience of being abandoned by a parent, then, would foster a sense
of mistrust in the world and would affect personality development. In the
1950’s, University of Wisconsin psychologist Harry Harlow (1905-1981) explored
the effects of attachment on later personality development. Harlow
concluded that rhesus monkeys who were separated from their mothers
shortly after birth displayed abnormal behaviors later in life, such as unusual
fear or aggression, difficulty engaging in mating behaviors, and difficulty
with parenting their offspring. Maternally deprived animals, therefore,
were more likely to display dysfunction, as is seen in individuals with
disorders associated with maternal deprivation, such as borderline and antisocial
personality disorders.
Genetic factors may be influential in the development of antisocial personality
disorder, as children of biological parents who engage in criminal behavior
are more likely to engage in criminal behavior themselves. Learning theorists
propose that antisocial behaviors may be learned by mimicking parents
with similar behaviors. Individuals with antisocial personality disorder have
displayed an abnormally low arousal level, which might enable them to ignore
physiological cues that indicate danger or punishment. Research has
also suggested that the unusually low level of arousal may cause the antisocial
individual to engage in behaviors which increase physiological arousal,
or create a “rush.” 608