Download Diathesis-Stress Model and Brain Development

The diathesis-stress model is a theory that explains behavior as a predispositional
vulnerability combined with stresses from life experience. Abnormal behavior can be
viewed as a combination of two types of factors, diathesis and stress. Diathesis includes
any previous biological and genetic factors that predispose an individual towards
developing a disorder (Butcher, J., Mineka, S., Hooley, J., 2004). Grant and Mcmahon
suggest that stress can be considered “any environmental circumstances or conditions that
threaten, challenge, exceed or harm the psychological or biological capacities of the
individual” (2005, p. 3). The terms vulnerability and resilience are associated with the
diathesis-stress model, the more vulnerable and less biologically resilient an individual is
to a particular psychological disorder, the lower the amount of stress it would require to
cause symptoms to be exhibited. On the other hand, if the individual has high resilience
and low biological vulnerability, it would require extreme amounts of stress to trigger
symptoms of that disorder.
The diathesis-stress model can be used to help us understand the environmental,
biological and socio-emotional factors that influence the developing brain. We
traditionally have used two evolutionary-inspired theoretical arguments to inform our
thoughts on biological and environmental impacts on brain development, biologicalsensitivity-to-context thesis and differential-susceptibility hypothesis. The former focused
on the role of nature in shaping individual differences in plasticity, without excluding the
role of nurture, and the latter has emphasized nurture, without excluding nature (Belsky
& Pluess, 2009). Dean argued that you can seldom say with certainty that a disorder
is “brain-based” or “environmental” in practice, because these descriptors should
be seen as the endpoints of an interactive continuum, not as an either–or
dichotomy (as cited in Hale, J.B and Fiorello, C.A, 2004). We now prefer to think of
the roles of nature and nurture as both being integral and defining in terms of brain
development, with no particular favorable influence being more or less important. There
are also what psychologists call ‘protective factors”, which modify a person’s response to
environmental stressors, making it less likely that the individual will experience the
adverse consequences of the stressors. Protective factors can be both positive and
negative experiences and both act to promote a sense of self-esteem and therefore a better
ability to cope with external stressors (Mineka and Hooley, 2004). An example of a
positive protective factor in childhood is having a family environment in which at least
one parent is warm and supportive, allowing the development of a good attachment
relationship between child and parent (Masten & Coatsworth, 1998). An example of a
negative protective factor would be the successful coping of a stressful situation(s) at a
young age that allow children to become more resilient to similar stressors later in life.
This “steeling” or “inoculation” effect is more likely to occur with moderate stressors
than with mild or extreme stressors (Butcher et al., 2004).
I want to focus on a particular environmental stressor that is well known in the field of
education for having a largely adverse impact on healthy brain development, and is a
constant topic in the analysis of diathesis-stress, which is growing up in a low socioeconomic setting.
Shoeman (2007) cites numerous studies that have investigated the differences between
the performances of high and low socio-economic status (SES) children on various
neuropsychological tests, including those assessing cognitive styles and problem- solving
skills, phonological sensitivity, classification and recall, and general academic
achievement. Results from these studies are consistent in showing that high SES children
perform better than low SES children, even when IQ is statistically controlled (Shoeman,
2007). There is also a lot of conflicting research, such as the studies done by Rosellis and
Ardila (2003) that suggest that children of parents with low levels of education and low
SES cannot be assumed to be somehow deprived of knowledge or skills; it is more
accurate to assume that they have just developed different types of learning than people
with higher levels of education. I bring up these two points because it is important to
understand that there is almost always going to be varying and often opposing evidence
when it comes to the importance that environmental factors have on brain development.
The ambiguity inherent in assessing environmental stressors and their causal
effects is one of the most difficult aspects of applying the diathesis-stress model to our
understanding of brain development. The difference between what is deemed a mild,
moderate or extreme stressor’s is never going to be invariable, nor will it ever be
objective. It is completely dependent on the individual and the countless other biological
and environmental variables that factor into whether the stressor will be turned into a
protective factor, that could build resilience, or whether the stressor will be enough to
trigger diathesis and cause the development of a disorder. This makes for almost zero
predictability of stressors as triggers in the diathesis-stress model and makes me question
the use of it as a tool in understanding brain development.
References
Belsky, J., & Pluess. M. (2009) Beyond Diathesis Stress: Differential Susceptibility to
Environmental Influences. Psychological Bulletin, 135(6). 885-908
doi: 10.1037/a0017376
Butcher, J.N., Mineka, S., Hooley, J.M., (2004). Abnormal Psychology (12th ed.)
Retrieved from http://www.scribd.com/doc/11482181/005-chapter-3-causalfactors-and-viewpoints0001
Hale, J. B., & Fiorello, C. A., (2004). School Neuropsychology: A Practitioner’s
Handbook. (p. 246). New York, NY: Guilford Publications.
Grant, K.E & Mcmahon, S.D., (2005). Conceptualizing the Role of Stressors in the
Development of Psychopathology. In B.L Hankin and J. R. Z. Abela’s (Eds.),
Development of Psychopathology: A Vulnerability-Stress Perspective. Retrieved
from
http://books.google.ca/books?id=1Fd0LneB724C&lpg=PR7&ots=b90ZsadHn&dq=Development+of+Psychopathology:+A+vulnerability+stress+perspective&l
r=&pg=PR7&redir_esc=y#v=onepage&q=Development%20of%20Psychopatholo
gy%3A%20A%20vulnerability%20stress%20perspective&f=false
Shoeman, F., (2007). Neuropsychological Performance of Low Socio-Economic Status
South African Children. (Unpublished doctoral dissertation). University of Cape
Town, Cape Town, South Africa. Retrieved from
http://www.psychology.uct.ac.za/postgraduate/Hons2007Projects/Fransien.Schoe
man.pdf