656 research outputs found
The case of late preterm birth: sliding forwards the critical window for cognitive outcome risk
Many survivors of preterm birth experience neurodevelopmental disabilities, such as cerebral palsy, visual and hearing problems. However, even in the absence of major neurological complications, premature babies show significant neuropsychological and behavioural deficits during childhood and beyond. While the clinical tools routinely used to assess neurocognitive development in those infants have been useful in detecting major clinical complications in early infancy, they have not been equally sensitive in identifying subtle cognitive impairments emerging during childhood. These methodological concerns become even more relevant when considering the case of late preterm children (born between 34 and 36 gestational weeks). Although these children have been traditionally considered as having similar risks for developmental problems as neonates born at term, a recent line of research has provided growing evidence that even late preterm children display altered structural and functional brain maturation, with potential life-long implications for neurocognitive functioning. A recent study by Heinonen put forward the hypothesis that environmental factors, in this case educational attainment, could moderate the association between late preterm birth (LPT) and neuropsychological impairments commonly associated with aging. In this paper we bring together clinical literature and recent neuroimaging evidence in order to provide two different but complementary approaches for a better understanding of the "nature-nurture" interplay underlying the lifespan neurocognitive development of preterm babies
Studying the brain from adolescence to adulthood through sparse multi-view matrix factorisations
Men and women differ in specific cognitive abilities and in the expression of
several neuropsychiatric conditions. Such findings could be attributed to sex
hormones, brain differences, as well as a number of environmental variables.
Existing research on identifying sex-related differences in brain structure
have predominantly used cross-sectional studies to investigate, for instance,
differences in average gray matter volumes (GMVs). In this article we explore
the potential of a recently proposed multi-view matrix factorisation (MVMF)
methodology to study structural brain changes in men and women that occur from
adolescence to adulthood. MVMF is a multivariate variance decomposition
technique that extends principal component analysis to "multi-view" datasets,
i.e. where multiple and related groups of observations are available. In this
application, each view represents a different age group. MVMF identifies latent
factors explaining shared and age-specific contributions to the observed
overall variability in GMVs over time. These latent factors can be used to
produce low-dimensional visualisations of the data that emphasise age-specific
effects once the shared effects have been accounted for. The analysis of two
datasets consisting of individuals born prematurely as well as healthy controls
provides evidence to suggest that the separation between males and females
becomes increasingly larger as the brain transitions from adolescence to
adulthood. We report on specific brain regions associated to these variance
effects.Comment: Submitted to the 6th International Workshop on Pattern Recognition in
Neuroimaging (PRNI
The impact of second language learning on semantic and nonsemantic first language reading
The relationship between orthography (spelling) and phonology
(speech sounds) varies across alphabetic languages. Consequently,
learning to read a second alphabetic language, that uses the same
letters as the first, increases the phonological associations that can
be linked to the same orthographic units. In subjects with English
as their first language, previous functional imaging studies have
reported increased left ventral prefrontal activation for reading
words with spellings that are inconsistent with their orthographic
neighbors (e.g., PINT) compared with words that are consistent
with their orthographic neighbors (e.g., SHIP). Here, using
functional magnetic resonance imaging (fMRI) in 17 Italian--English
and 13 English--Italian bilinguals, we demonstrate that left ventral
prefrontal activation for first language reading increases with
second language vocabulary knowledge. This suggests that
learning a second alphabetic language changes the way that
words are read in the first alphabetic language. Specifically, first
language reading is more reliant on both lexical/semantic and
nonlexical processing when new orthographic to phonological
mappings are introduced by second language learning. Our
observations were in a context that required participants to switch
between languages. They motivate future fMRI studies to test
whether first language reading is also altered in contexts when the
second language is not in use
Delay in presentation of symptomatic referrals to a breast clinic: patient and system factors
We attempted to identify factors associated with delay in presentation and assessment of women with breast symptoms who attended a London breast clinic. A total of 692 consecutive symptomatic referrals, aged 40β75 years, were studied. Patient delay, assessed prior to diagnosis, was defined as time elapsing between symptom discovery and first presentation to a medical provider. This was studied in relation to: reasons for delaying, beliefs and attitudes, socio-demographic and clinical variables, psychiatric morbidity and subsequent diagnosis. Thirty-five per cent of the cohort delayed presentation 4 weeks or more (median 13 days). The most common reason given was that they thought their symptom was not serious (odds ratio (OR) = 5.32, 95% confidence interval (CI) 3.6β8.0). Others thought their symptom would go away (OR = 3.73, 95% CI 2.2β6.4) or delayed because they were scared (OR = 4.61, 95% CI 2.1β10.0). Delay was associated with psychiatric morbidity but not age. Patients who turned out to have cancer tended to delay less (median 7 days) but not significantly. Median system delay β time between first medical consultation and first clinic visit β was 18 days. Patients who thought they had cancer and those so diagnosed were seen more promptly (median 14 days). Most factors, including socio-economic status and ethnicity were non-contributory. Beliefs about breast symptoms and their attribution are the most important factors determining when women present. Health education messages should aim to convince symptomatic women that their condition requires urgent evaluation, without engendering fear in them. Β© 2000 Cancer Research Campaig
Altered Cortical Gyrification in Adults Who Were Born Very Preterm and Its Associations With Cognition and Mental Health
Background: The last trimester of pregnancy is a critical period for the establishment of cortical gyrification, and altered folding patterns have been reported following very preterm birth (\u3c 33 weeks of gestation) in childhood and adolescence. However, research is scant on the persistence of such alterations in adulthood and their associations with cognitive and psychiatric outcomes. Methods: We studied 79 very preterm and 81 age-matched full-term control adults. T1-weighted magnetic resonance images were used to measure a local gyrification index (LGI), indicating the degree of folding across multiple vertices of the reconstructed cortical surface. Group and group-by-sex LGI differences were assessed by means of per-vertex adjustment for cortical thickness and overall intracranial volume. Within-group correlations were also computed between LGI and functional outcomes, including general intelligence (IQ) and psychopathology. Results: Very preterm adults had significantly reduced LGI in extensive cortical regions encompassing the frontal, anterior temporal, and occipitoparietal lobes. Alterations in lateral fronto-temporal-parietal and medial occipitoparietal regions were present in both men and women, although men showed more extensive alterations. In both very preterm and control adults, higher LGI was associated with higher IQ and lower psychopathology scores, with the spatial distribution of these associations substantially differing between the two groups. Conclusions: Very preterm adultsβ brains are characterized by significant and widespread local hypogyria, and these alterations might be implicated in cognitive and psychiatric outcomes. Gyrification reflects an early developmental process and provides a fingerprint for very preterm birth
Subregional hippocampal morphology and psychiatric outcome in adolescents who were born very preterm and at term
Background: The hippocampus has been reported to be structurally and functionally altered as a sequel of very preterm birth ( < 33 weeks gestation), possibly due its vulnerability to hypoxic-ischemic damage in the neonatal period. We examined hippocampal volumes and subregional morphology in very preterm born individuals in mid- and late adolescence and their association with psychiatric outcome. Methods: Structural brain magnetic resonance images were acquired at two time points (baseline and follow-up) from 65 ex-preterm adolescents (mean age = 15.5 and 19.6 years) and 36 termborn controls (mean age=15.0 and 19.0 years). Hippocampal volumes and subregional morphometric differences were measured from manual tracings and with three-dimensional shape analysis. Psychiatric outcome was assessed with the Rutter Parents' Scale at baseline, the General Health Questionnaire at follow-up and the Peters Delusional Inventory at both time points. Results: In contrast to previous studies we did not find significant difference in the cross-sectional or longitudinal hippocampal volumes between individuals born preterm and controls, despite preterm individual having significantly smaller whole brain volumes. Shape analysis at baseline revealed subregional deformations in 28% of total bilateral hippocampal surface, reflecting atrophy, in ex-preterm individuals compared to controls, and in 22% at follow-up. In ex-preterm individuals, longitudinal changes in hippocampal shape accounted for 11% of the total surface, while in controls they reached 20%. In the whole sample (both groups) larger right hippocampal volume and bilateral anterior surface deformations at baseline were associated with delusional ideation scores at follow-up. Conclusions: This study suggests a dynamic association between cross-sectional hippocampal volumes, longitudinal changes and surface deformations and psychosis proneness. Copyright
Neonatal Brain Injury and Neuroanatomy of Memory Processing following Very Preterm Birth in Adulthood: An fMRI Study
Altered functional neuroanatomy of high-order cognitive processing has been described in very preterm individuals (born before 33 weeks of gestation; VPT) compared to controls in childhood and adolescence. However, VPT birth may be accompanied by different types of adverse neonatal events and associated brain injury, the severity of which may have differential effects on brain development and subsequent neurodevelopmental outcome. We conducted a functional magnetic resonance imaging (fMRI) study to investigate how differing degrees of neonatal brain injury, detected by neonatal ultrasounds, affect the functional neuroanatomy of memory processing in VPT young adults. We used a verbal paired associates learning task, consisting of four encoding, four cued-recall and four baseline condition blocks. To further investigate whether differences in neural activation between the groups were modulated by structural brain changes, structural MRI data were also collected. We studied 12 VPT young adults with a history of periventricular haemorrhage with associated ventricular dilatation, 17 VPT individuals with a history of uncomplicated periventricular haemorrhage, 12 individuals with normal ultrasonographic findings, and 17 controls. Results of a linear trend analysis demonstrated that during completion of the paired associates learning task right frontal and right parietal brain activation decreased as the severity of neonatal brain injury increased. There were no statistically significant between-group differences in on-line task performance and participants' intelligence quotient (IQ) at assessment. This pattern of differential activation across the groups was observed particularly in the right middle frontal gyrus during encoding and in the right posterior cingulate gyrus during recall. Structural MRI data analysis revealed that grey matter volume in the right superior temporal gyrus, right cerebellum, left middle temporal gyrus, right globus pallidus and right medial frontal gyrus decreased with increasing severity of neonatal brain injury. However, the significant between-group functional neuroanatomical differences were not directly attributable to the detected structural regional differences
White Matter and Cognition in Adults Who Were Born Preterm
BACKGROUND AND PURPOSE: Individuals born very preterm (before 33 weeks of gestation, VPT) are at risk of damage to developing white matter, which may affect later cognition and behaviour. METHODS: We used diffusion tensor MRI (DT-MRI) to assess white matter microstructure (fractional anisotropy; FA) in 80 VPT and 41 term-born individuals (mean age 19.1 years, range 17-22, and 18.5 years, range 17-22 years, respectively). VPT individuals were part of a 1982-1984 birth cohort which had been followed up since birth; term individuals were recruited by local press advertisement. General intellectual function, executive function and memory were assessed. RESULTS: The VPT group had reduced FA in four clusters, and increased FA in four clusters relative to the Term group, involving several association tracts of both hemispheres. Clusters of increased FA were associated with more severe neonatal brain injury in the VPT group. Clusters of reduced FA were associated with lower birth weight and perinatal hypoxia, and with reduced adult cognitive performance in the VPT group only. CONCLUSIONS: Alterations of white matter microstructure persist into adulthood in VPT individuals and are associated with cognitive function
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