Wouter Groen PhD MD

Child Psychiatrist at Karakter

Senior Researcher Donders Centre

Cognitive Neuroimaging

clinical fellowship F2010(1)-13

a little history

descriptive nosology in Middle Ages

renaissance’s empiricism

a biological diagnostic instrument

from descriptive to biological understanding

psychiatry’s renaissance: empiricism

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Patient

Control

autism symptom vs. biomarker

age of discovery: focus on theory

background

method

results

results

evidence for developmental derailment: children with autism look longer at irrelevant parts of visual scenes the effects disappeared when corrected for IQ

conclusions

developmental derailment on biomarkers

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

IQ vs. disorder

IQ distribution

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is the difference between 70 and 100…

… as functionally meaningful as the difference between 160 and 190?

how does IQ (distribution!) map onto ability?

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IQ

Functional disability

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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take home message

issues In intellectual disability research include: non-linearity of IQ and IQ-disease dependency.

any questions

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.

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.

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.

Thanks for listening