Front Matter

38 Introduction to Autism Spectrum Disorders

Figure 1.19 depicts how exposure to alcohol can manifest itself in the form of

fetal alcohol spectrum disorder (FASD), which is characterized by intellectual

deficiency as well as a combination of deformities of the face, brain, heart,

genitals, bones and joints, and growth retardation. The head may be abnor­

mally small with inadequate development of the brain. In general, alcohol has

a negative effect on every aspect of the early development of the nervous sys­

tem including the differentiation of new neurons, migration patterns of nerve

cells, and the formation of synapses, and myelination of nerve pathways [78].

From FASD one can imagine how exposure to alcohol at different times of

gestation and at different concentrations can result in a spectrum of pheno­

types with small head, low nasal bridge, epicanthal folds, small eye openings,

flat midface, short nose, thin upper lip, smooth philtrum, and maldeveloped

jaw. Most importantly, it ought to be emphasized that alcohol enters every cell

in the fetal body, resulting in an overall retardation in brain size as opposed to

fragrances and other synthetic chemicals that can selectively bind specific pro­

genitor neurons via receptors and can exert compartmentalized effects, killing

some neurons and allowing the surviving cells to grow faster in the areas of the

brain that are emptied due to the killing of certain neurons. Therefore, syn­

thetic chemical effects show a more subtle spectrum, difficult to visualize

(unlike FASD), and even harder to diagnose at birth. Usually, ASD is not diag­

nosable until 3 years of age.

One can image that depletion or significant reduction of some types of

progenitor cells can prompt other types of progenitor cells to replace them,

which can grow faster than the original cells and create a brain with a far higher

number of neurons in the frontal cortex and an astronomical number of faulty

neuronal synapses and connections that may function in an aberrant fashion.

Low nasal bridge

Epicanthal folds

Short palpebral

ssures

Flat midface

Smooth philtrum

Small head

Small eye

openings

Short nose

Thin upper lip

Figure 1.19 The development of a fetus exposed to alcohol (fetal alcohol spectrum

disorder or FASD). Source: Adapted from http://virtual‐lecture‐hall.com/

KRA2605cssCHAPTER3/images/Fetal‐Alcohol‐Syndrome‐Characteristics.jpg.