PROMOTING POTENTIAL 299those who had been adopted into regular homes in the United Kingdom
at vari ous ages.
In fact, most adoptees showed rapid recovery psychologically, although
a signifi cant minority, especially of those adopted aft er six months, con-
tinued to experience behavioral prob lems. Th e most recent report, into
early adulthood, notes “a striking pattern of behavioral impairments, in
its core characterized by defi cits in social cognition and be hav ior, as well
as quasi- autistic features, oft en accompanied by cognitive impairment
and symptoms of attention- defi cit/hyperactivity disorder (ADHD).”^15
It is known that an adverse fetal environment permanently programs
physiology, leading to increased risks of cardiovascular, metabolic, and
neuroendocrine disorders in adulthood.^16 High levels of stress during
pregnancy have been associated with a number of long- term adverse psy-
chological, as well as physiological, outcomes for both mother and child.
Research has also suggested that stress in the home, experienced dur-
ing infancy, can result in greater stress reactivity in later life. Th at, in
turn, diminishes confi dence and focus in school.^17 As mentioned in
chapter 4, stress experienced even before pregnancy can be passed on to
the next generation through epige ne tic eff ects, or the way that genes are
utilized in an embryo, so that children, and even grandchildren, may
suff er.
Understanding such fi ndings is not straightforward, however, as re-
sults are oft en inconsistent. For example, experience of stress and mea-
sured circulating stress hormones do not always correlate in the way
expected, perhaps due to individual diff erences in stress management
(itself requiring additional explanation).^18 As Kumsta and colleagues
report about the Romanian children, heterogeneity in outcome is largely
unexplained.
Other studies have investigated eff ects of “enriched” or “impover-
ished” environments on brain development and cognitive functions spe-
cifi cally. Th e environments have usually been conceived in very general
terms as ones containing many or fewer stimuli, objects, and opportuni-
ties for exercise. For example, studies in the 1960s and 1970s showed that
rearing rats in the dark diminishes the nerve cell connections, as well as
amino acid and protein production, in visual areas of the brain.
In the 1960s, Mark Rosensweig and colleagues started a long line of
research comparing rats reared in normal, sparsely equipped, cages with
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