Psychiatric Mental Health Nursing by Videbeck

440 Unit 4 NURSINGPRACTICE FORPSYCHIATRICDISORDERS

anorexia nervosa on chromosome 1. Genetic vulner-
ability also might result from a particular personal-
ity type or a general susceptibility to psychiatric dis-
orders. Or it may directly involve a dysfunction of
the hypothalamus (Halmi, 2000). A family history of
mood or anxiety disorders (e.g., obsessive-compulsive
disorder) places a person at risk for an eating dis-
order. Wade, Bulick, Neale & Kendler (2000) attrib-
uted 58% of cases of anorexia nervosa to heritability
but could not totally discount the influence of a shared
environment.
Disruptions of the nuclei of the hypothalamus
may produce many of the symptoms of eating disor-
ders. Two sets of nuclei are particularly important in
many aspects of hunger and satiety(satisfaction of
appetite): the lateral hypothalamus and the ventro-
medial hypothalamus. Deficits in the lateral hypo-
thalamus result in decreased eating and decreased
responses to sensory stimuli that are important to
eating. Disruption of the ventromedial hypothalamus
leads to excessive eating, weight gain, and decreased
responsiveness to the satiety effects of glucose, which
are behaviors seen in bulimia.
Many neurochemical changes accompany eating
disorders, but it is difficult to tell whether they cause
or result from eating disorders and the characteris-
tic symptoms of starvation, binging, and purging. For
example, norepinephrine levels rise normally in re-
sponse to eating, allowing the body to metabolize and
to use nutrients. Norepinephrine levels do not rise
during starvation, however, because few nutrients
are available to metabolize. Therefore, low norepi-
nephrine levels are seen in clients during periods of
restricted food intake. Also, low epinephrine levels
are related to the decreased heart rate and blood
pressure seen in clients with anorexia.

Increased levels of the neurotransmitter sero-

tonin and its precursor tryptophan have been linked

with increased satiety. Low levels of serotonin as

well as low platelet levels of monoamine oxidase have

been found in clients with bulimia and the binge and

purge subtype of anorexia nervosa (Carrasco, Diaz-

Marsa, Hollander, Cesar & Saiz-Ruiz, 2000); this

may explain binging behavior. The positive response

of some clients with bulimia to treatment with selec-

tive serotonin reuptake inhibitor antidepressants

supports the idea that serotonin levels at the synapse

may be low in these clients.

Developmental Factors

ANOREXIA NERVOSA

Onset of anorexia nervosa usually occurs during ado-

lescence or young adulthood. Some researchers believe

its causes are related to developmental issues.

Two essential tasks of adolescence are the strug-

gle to develop autonomy and the establishment of a

unique identity. Autonomy, or exerting control over

oneself and the environment, may be difficult in fam-

ilies that are overprotective or in which enmeshment

(lack of clear role boundaries) exists. Such families do

not support members’ efforts to gain independence,

and teenagers may feel as though they have little or

no control over their lives. They begin to control their

eating through severe dieting and thus gain control

over their weight. Losing weight becomes reinforc-

ing: by continuing to lose, these clients exert control

over one aspect of their lives.

Serpell, Treasure, Teasdale & Sullivan (1999)

studied girls with anorexia nervosa to determine pos-

itive or reinforcing aspects of the disorder. Two main

themes were conforming to a strict diet and fitting

Table 18-2

RISKFACTORS FOREATINGDISORDERS

Developmental Sociocultural

Disorder Biologic Risk Factors Risk Factors Family Risk Factors Risk Factors

Anorexia nervosa

Bulimia nervosa

Obesity; dieting at

an early age

Obesity; early dieting;

possible serotonin

and norepineph-

rine disturbances;

chromosome 1

susceptibility

Issues of developing

autonomy and

having control

over self and envi-

ronment; develop-

ing a unique iden-

tity; dissatisfaction

with body image

Self-perceptions of

being overweight,

fat, unattractive,

and undesirable;

dissatisfaction

with body image

Family lacks emo-

tional support;

parental maltreat-

ment; cannot deal

with conflict

Chaotic family with

loose boundaries;

parental maltreat-

ment including

possible physical

or sexual abuse

Cultural ideal of

being thin; media

focus on beauty,

thinness, fitness;

preoccupation

with achieving the

ideal body

Same as above;

weight-related

teasing