Brain Development: Normal Processes and the Effects of Alcohol ...

Influence of Alcohol on Structur e
of the Developing Human Brain
A diagnosis of fetal alcohol syndrome (FAS) requires a
combination o f three clusters o f symptoms: (1 ) a distinct
craniofacia l appearance, (2 ) growt h deficiency ,
and (3 ) centra l nervou s syste m (CNS ) dysfunction .
Characteristic FAS-relate d craniofacia l dysmorphol -
ogy includes short palpebrai fissures (eye openings), a
smooth philtrum (the area above the upper lip), a flat
nasal bridge an d mid-face , and thinnes s o f the uppe r
lip. Th e growt h deficienc y related t o FA S manifests
either prenatall y and/or postnatally, and ca n necessi -
tate neonatal car e for failure to thrive. The thir d clas s
of symptoms , CN S dysfunctio n an d accompanyin g
structural brain changes , ar e the subjec t of the pres -
ent chapter. The effect s o f prenatal alcoho l exposur e
on cognitio n an d behavio r ar e variabl e an d wide -
reaching. Commo n difficultie s includ e attentio n
deficits; decrement s i n genera l intelligenc e quotien t
(IQ); behavioral problems; visual , auditory, and per -
ceptual disturbances ; fin e an d gros s motor problems ;
and learnin g disabilitie s (Streissgut h an d Connor ,
2001). Indeed , th e syndrom e ha s bee n cite d a s th e
9
Susanna L. Fryer
Christie L. McGee
Andrea D. Spadon i
Edward P. Riley
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leading preventable cause of mental retardatio n (Pulsifer,
1996) .
The stud y o f brai n structur e i n alcohol-expose d
individuals offers a means to understand the etiologi -
cal relationship s tha t underli e th e neurobehaviora l
abnormalities observed i n thes e individuals . By examining
relationships between brain structure and behavior,
we gain insight s int o th e mechanism s underlyin g
alcohol teratogenicity. Before delving into a discussion
of brain structural changes arisin g from feta l alcoho l
exposure, i t is important t o ad d a not e o n terminol -
ogy. In recognitio n of the wide-rangin g effect s of
prenatal alcohol exposure, the term fetal alcohol spectrum
disorders (FASD ) ha s been adopte d t o describ e
the entir e rang e o f outcomes fro m prenata l alcoho l
exposure (Bertran d e t al. , 2004) . Thes e effect s var y
from th e pronounced facial , growth, and CNS abnor -
malities traditionally ascribed to FAS , to subtl e neu -
robehavioral, growth , o r physica l deficit s tha t ma y
also occu r a s a resul t o f suc h exposure . Usin g thi s
classification, FA S corresponds to dysmorphic FAS D