This talk by dr. Wouter Groen, child psychiatrist and neuroscientist at Karakter, was given at the 2014 Karakter Conference in Ede, The Netherlands. The talk deals with the issue of biomarkers for psychiatric disorders. It specifically addresses the issue of why it has proven so difficult to actually find biomarkers suited for daily clinical practice.
28. results
evidence for developmental derailment:
children with autism look longer at irrelevant
parts of visual scenes
the effects disappeared when corrected for IQ
31. why biomarkers do
not differentiate well
biomarkers are influenced
by genes and environment
equally; subtle differences
are amplified during
derailment
low IQ and disorder
intertwined
36. how does IQ (distribution!) map
onto ability?
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IQ
Functional disability
37. IQ is an order statistic
IQ represents rankorder, not
linear ability, especially at the
ends of the IQ range
therefore, parametrics
statistics should not be used
with IQ data (i.e. correlation,
confounders, etc)
instead, use non-parametric
rank statistics
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38. take home message
issues In intellectual disability research include:
non-linearity of IQ and IQ-disease dependency.
40. Outline
• Psychiatric disorders are currently behaviorally
defined (similar to somatic disorders in the
Middle Ages).
• To bring psychiatry into the modern age, the
scientific community has been in search of
biomarkers (similar to somatic medicine in the
early renaissance).
• Finding meaningful and useful biomarkers has
proven extremely difficult.
41. Outline continued
• Typically, dimensional symptom scores overlap
between patients and controls. Importantly, so do
biomarkers, rendering them quite useless for
diagnosis.
• In the late renaissance, scientists combined
empiricism with theorizing, opening the door to
the modern age.
• Similarly, better theories in current psychiatry may
provide better biomarkers. Complex theories,
however, bring about complex issues.
42. Outline continued
• In intellectual disability research, these issues
include: non-linearity of IQ and IQ-disease
dependency.
• I would like to invite everybody to comment on
these two issues.