You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
The structural brain correlates of cognitive deficits in adults with Klinefelter's syndrome.
Abstract 1:
CONTEXT Adults with Klinefelter 's syndrome ( KS ) are known to present disturbances of language skills and delayed learning abilities . OBJECTIVES The aim of this study was to assess brain morphometry in KS and to correlate eventual volumetric changes with performance on neuropsychological tests . PATIENTS Patients included 18 KS adults and 20 age-matched controls . METHODS All participants underwent prospect ively double-spin-echo brain magnetic resonance imaging and neuropsychological testing of verbal and nonverbal domains . On the axial stack of magnetic resonance imaging slices , regional brain volumes were measured either by automated segmentation ( full brain , total cerebrospinal fluid , and ventricular volume ) or manual drawing with help of a neuroanatomy atlas ( frontal , temporal , and parietal lobes , gray matter component of the lobes , cerebellar hemispheres , and hippocampal complexes ) . RESULTS KS patients performed significantly lower than controls on language -related tasks exploring verbal processing speed and verbal executive function . They were diagnosed with significant enlargement of ventricular volume and bilateral reduction of cerebellar hemispheres . Furthermore , after separation of participants according to h and edness and after correction of regional brain volumes for atrophy , a significant reduction of left temporal lobe volume was found in KS compared with controls . Ventricular volume was inversely correlated with cognitive function , whereas left temporal lobe volume was positively correlated with language -related tasks . CONCLUSION This study hypothesizes that supernumerary X-chromosome and /or congenital hypogonadism provoke structural alterations in the subcortical pathways involved in language processing , thus providing a neurobiological substrate for cognitive deficits in KS


Title 2:
Individual inconsistency across measures of inhibition: an investigation of the construct validity of inhibition in older adults
Abstract 2:
Inhibition is a central construct to the frontal lobe theory of ageing , yet its construct validity remains unproven . Furthermore , age effects on measures of inhibition are often reported without adequate control for the effects of global slowing on performance . We investigated inhibitory function in older adults in two experiments . In Experiment 1 , 49 people with ages between 59 and 86 ( mean=70 years 9 months S.D.=7.54 ) completed four analogues of the Stroop interference paradigm . To control for global slowing and to enable comparisons across all measures , we used a r and om effects model based on log-transformed response times . Age did not contribute significantly to the model and the estimated correlation between tasks was not significant . In Experiment 2 , 33 people with ages between 62 and 86 ( mean=73 years 4 months , S.D.=6.57 ) were compared on two measures of  Stroop-like interference  which were very similar in surface task dem and s. Age did not contribute significantly to the model but the estimated correlation between tasks was robust ( r=0.714 ) . We conclude that age may make little contribution to inhibitory function independently of other factors such as speed and intelligence . Second , that the level of individual consistency in the performance of measures of inhibition will depend on the similarity of the tasks used


Title 3:
Brain morphology in Klinefelter syndrome
Abstract 3:
Objective : This study focuses on variation in brain morphology associated with supernumerary X chromosome and Klinefelter syndrome ( KS ) . Using an unselected birth cohort of KS subjects and high-resolution MRI , the authors investigated the neuroanatomic consequences of the 47,XXY karyotype in the presence and absence of exogenous testosterone supplementation . Methods : Regional brain volumes were measured in 10 subjects with KS and 10 age-matched control men . Five of the KS subjects had received testosterone supplementation since puberty ( KS+T ) and five had not  ( KS−T ) . Results : KS subjects showed significant ( p < 0.01 ) reduction in left temporal lobe gray matter volumes compared with normal control subjects . Differences in left temporal gray volumes were also significant between the KS+T and KS−T groups ( p < 0.01 ) . Verbal fluency scores were significantly different between the KS+T and KS−T groups as well . Conclusion : Supernumerary X chromosome material in men is associated with a reduction in left temporal lobe gray matter , a finding that is consistent with the verbal and language deficits associated with KS . Also , relative preservation of gray matter in the left temporal region is associated with exposure to exogenous and rogen during development . A history of testosterone supplementation also appears to be associated with increased verbal fluency scores in KS patients


Title 4:
Sex chromosome anomalies, hormones, and aggressivity.
Abstract 4:
This double-blind , controlled study of XYY and XXY men found in a birth cohort of 4,591 tall men born in Copenhagen assessed evidence of delinquent and aggressive behavior and explored the role of hormonal determinants in the behavioral and psychological differences noted among groups . Information from social records , a structured psychological interview , and projective tests did not support the notion that men with sex chromosome anomalies are particularly violent or aggressive . Hormonally , XYY men had significantly higher concentrations of testosterone , luteinizing hormone ( LH ) , and follicle-stimulating hormone ( FSH ) than matched control groups . In contrast , XXY men had higher levels of LH , FSH , and prolactin , but low concentrations of testosterone . There was a significantly positive relation among all subjects as well as XY controls alone between plasma testosterone level and evidence of criminal convictions . A proportionate increase in testosterone levels was noted when subjects were divided into nondelinquents , delinquents without violent convictions , and delinquents with violent convictions . The relation between testosterone level and criminal behavior was not reflected in measures of aggression derived from the psychological interview and projective tests . There was no specific evidence that testosterone is a mediating factor in the criminal behavior of XYY men


Title 5:
Fifty-one prenatally diagnosed children and adolescents with sex chromosome abnormalities.
Abstract 5:
Children with sex chromosome abnormalities ( SCA ) are known to be at risk for developmental delays . These risks were identified 2 decades ago by seven international research groups who prospect ively followed children ascertained after birth . Subsequently , some of these investigators suggested the course of prenatally identified children with SCA may be different from children in earlier studies . The first such evidence was published by Robinson et al. [ 1992 : Am J Med Genet 44:365 - 368 ] , who compared 20 prenatally diagnosed children to the original postnatally diagnosed cohort . The following report presents an up date and expansion of that research and includes 51 children and adolescents prenatally diagnosed with SCA , now 7 - 18 years of age . Results confirm that this cohort of prenatally diagnosed children has a milder developmental course than children ascertained postnatally . The study provides new information to health professionals counseling families faced with prenatal diagnosis of SCA


Title 6:
Early development of children with sex chromosome aberrations.
Abstract 6:
A prospect i ve study was made of 42 children who were found at birth to have sex chromosome aberrations . The mean developmental quotient of the XXY and XXX groups was in the dull-normal range , whereas developmental quotients of 3 XYY children were low normal . The commonest deficits were in language and gross motor skills , with highest incidence in the XXX group . Many of the children had behavior problems , but no specific pattern was associated with an individual chromosome aberration . The XXX group experienced a linear growth spurt after 4 years of age . With one exception there were only mild dysmorphic features , none of them specifically associated with any subgroup . Of 17 children followed up to school age , almost two thirds evidence d learning and /or behavior problems . There was a high incidence of birth problems particularly in XXX children ( seven of ten ) , and of social problems , psychiatric illness and learning difficulties in their families . In 14 cases , the parent-child relationship was disturbed , result ing in behavior problems . These findings make it improbable that the children 's generally poor developmental and behavioral performance were solely attributable to their chromosomal constitution
Individuals with an additional X chromosome had mean IQs that were within broadly normal limits but lower than the respective comparison groups , with verbal IQ most affected .
Cognitive outcomes were poorest for females with XXX .
Males with XYY had normal-range IQs , but all three SCT groups ( XXX , XXY , and XYY ) had marked difficulties in speech and language , motor skills , and educational achievement .
Nevertheless , most adults with SCTs lived independently .
Less evidence was available for brain structure and for attention , social , and psychiatric outcomes .
INTERPRETATION Individuals with SCTs are at risk of cognitive and behavioural difficulties .