Prevalence and Aetiology of Prematurity
Average 1 in 10
->1 million die each year
Known causes:
- Multiple pregnancies
- Infections
- Chronic conditions – diabetes, high BP
- Genetic contribution
Not all causes are known
Cognitive Outcomes: EPiCURE study
Extremely premature
Cognitive Outcomes: Johnson et al. 2009
> 50% will have cognitive difficulties
Perform less well in a number of domains: >Language, literacy, numeracy and EF
IQ 10-20 points lower
Brain abnormalities are common and linked to early developmental outcomes
Neural Explanation behind lowered Cognitive Outcomes:
WM and CC = IQ
Development of WM during preterm phase is highly important!
- IQ related to gestational age
- Periventricular WM reduction and reduced CC
- Prems reduced WM – regardless of lesion or not
- > 70% of variance in IQ explained by: GLOBAL WM volume and CC volume
- ->100ml reduction in WM = 18 point drop
- ->100m2 in CC = 8 point drop
- Reduced WM volume and parent rated behaviour difficulties
- Correlates with GCSE passes
Neural Explanations: Speech
Language deficits more common in Prem Adolscents (Northam 2012)
> Children with a lesion at cUS at birth
L.lateralisation at follow-up – linked to speech/oromotor difficulties
> Left posterior Limb of the internal capsule (PLIC) + left primary motor tract
Neural Explanation: Language
Language deficits more common in Prem Adolscents (Northam 2012)
WM and CC = Language
Neural Correlates of Intelligence:Hypothesis 1: BRAIN VOLUME = IQ
R = 0.3-0.4 (Luders 2009) = 10% of people
- driven by genes (Posthuma 2002)
Intelligence and volumes of frontal, parietal, temporal cortices + hippocampus r= Less that .25
IQ is related to thickness in PFC and Temporal lobes
Developmental trajectory:
- Smarter: Early childhood = thin cortices;
Until puberty = increase PFC and Temporal; then decrease
Anecdotal:
Lesion size = IQ – NO!
Scan of large lesion: actual volume of GM/WM is normal
Scan of small lesion: actual volume of GM/WM is reduced
Neural Correlates of Intelligence:Hypothesis 2: P-FIT theory
Parieto-Frontal Integration Theory
Extrastriate Cortex (18-19) + Fusiform Gyrus (37) ==> recognition, imagery and elaboration of visual input
Wernicke’s area (22) ==> syntactic auditory input
Supramarginal (40) + superior parietal (7) + angual gyri (39) ==> captures sensory information and turn into symbolism, abstraction and elaboration
Parietal interact with Frontal regions = Working memory network to compare different responses
6, 9, 10, 45, 46, 47
Anterior Cingulate Cortex (32) ==> support inhibition of alternate responses
Small world Network
Higher intelligence = uninterrupted information transfer among the brain regions
New studies have found positive correlations between:
Intelligence N-Acetyl aspartate
Water Diffusion in centrum Semiovale (DTI) Intelligence
FMRI studies
- Distributed Network (similar to P-FIT)
- More efficient processing – especially in Frontal and Parietal
- ->Use fewer brain resources
- ->Resting brain network (less activity in a frontal and parietal network) linked to frontal and parietal regions activated in high cognitive tasks
Neural Correlates of Intelligence:
Hypothesis 3: CC
Einsteins anterior and posterior CC = larger
Particularly connections of parietal lobes (Mathematical reasoning?)
Neural Correlates of Intelligence:Hypothesis 4: Lesion distribution
Glascher et al. 2009 & 2010
Specific WM lesions linked to domain specific deficits in adults
- left inferior frontal cortex for VCI,
- left frontal and parietal cortex for WMI
- right parietal cortex for POI
- No single location for PSI
Intelligence draws on connections between regions that integrate verbal, visuospatial, working memory, and executive processes.
Sickle Cell VS. Prems: WM & IQ
Global WM modest relation to IQ
- Unlike PREMS!
Focal WM density reduction = main contributor to IQ decrement
- Unlike PREMS!
Brain development + Prems
- Early Fetal Phase
Thalmocortical connections - Early Premature Phase 23-32 weeks
Cortico-cortical projection
Callosal Projections - Late pre-term phase 32-36 wks
U-fibres
Retraction of callosal fibres
Biomarkers + Intervention
Early intervention trial: Erythropoietin
a drug that prevents WM injury
–>there is a positive effect on WM development - we do no know impact behaviourally yet
Biomarkers of Prems
Reduced WM reduced CC volume Reduced GM volume Left laterisation lesion = oromotor difficulties Temporal Splenium + AC = 57% of variance
Cognitive explanation behind lowered abilities
Lowered IQ impact performance on tests of other domains
IQ and memory/language/processing speed= 0.7+ Deary et al. 2010
LI not assciated with:
Northam 2012
Arcuate Fasciculus
LI associated with:
- Posterior CC – Splenium
- ->Temporal lobe connection were only reduced
But only in conjuction with: small anterior commissure
=> Temporal Splenium + AC = 57% of variance
- Bilateral volume reduction in ventral language pathways
