This paper presents translational aspects of imaging and genetic studies of language and cognition in children with epilepsy of average intelligence. It also discusses current unanswered translational questions in each of these research areas. A brief review of multimodal imaging and language study findings shows that abnormal structure and function, as well as plasticity and reorganization in language-related cortical regions are found both in children with epilepsy with normal language skills and in those with linguistic deficits. The review on cognition highlights that multiple domains of impaired cognition and abnormalities in brain structure and/or connectivity are evident early on in childhood epilepsy and might be specific for epilepsy syndrome. The description of state of the art genetic analyses that can be used to explain the convergence of language impairment and Rolandic epilepsy includes a discussion of the methodological difficulties involved in these analyses. Two junior researchers describe how their current and planned studies address some of the unanswered translational questions regarding cognition and imaging and the genetic analysis of speech sound disorder, reading, and centrotemporal spikes in Rolandic epilepsy.
language; cognition; imaging; genetics; pediatric epilepsy
The heterogeneity of symptoms and cognitive deficits in schizophrenia can be explained by abnormal connectivity between brain regions. Childhood-onset schizophrenia (COS) is a particularly severe form of schizophrenia, with an onset during a key time period for both cerebral pruning and myelination.
Diffusion tensor images were acquired from 18 children and adolescents with COS and 25 controls. The COS group was divided into two sub-groups--one with linguistic impairment (LI) and the other without (NLI). The fractional anisotropy (FA), axial (AD), and radial diffusivity (RD) data from the two COS sub-groups were compared to each other and to the controls using tract-based spatial statistics (TBSS) analyses, which is a voxel-based method used to identify regions of white matter abnormalities.
TBSS identified several regions in the left hemisphere where the LI group had increased AD and RD relative to the NLI and the control groups. These areas primarily localized to linguistic tracts: left superior longitudinal fasciculus and left inferior longitudinal fasciculus/inferior fronto-occipital fasciculus. Regions of increased RD overlapped regions of increased AD, with the former showing more pronounced effects.
Studies of adult-onset schizophrenia typically identify areas of higher RD but unchanged AD; however, normal development studies have shown that while RD decreases are pronounced over this age range, smaller decreases in AD can also be detected. The observed increases in both RD and AD suggest that developmental disturbances affecting the structural connectivity of these pathways are more severe in COS accompanied by severe linguistic impairments.
Diffusion tensor imaging; Axial diffusivity; Radial diffusivity; Linguistic impairments; Neurodevelopment
To examine whether family history of unprovoked seizures is associated with behavioral disorders in epilepsy probands, thereby supporting the hypothesis of shared underlying genetic susceptibility to these disorders.
We conducted an analysis of the 308 probands with childhood onset epilepsy from the Connecticut Study of Epilepsy with information on first degree family history of unprovoked seizures and of febrile seizures whose parents completed the Child Behavior Checklist (CBCL) at the 9-year follow-up. Clinical cut-offs for CBCL problem and DSM-Oriented scales were examined. The association between first degree family history of unprovoked seizure and behavioral disorders was assessed separately in uncomplicated and complicated epilepsy and separately for first degree family history of febrile seizures. A subanalysis, accounting for the tendency for behavioral disorders to run in families, adjusted for siblings with the same disorder as the proband. Prevalence ratios were used to describe the associations.
In probands with uncomplicated epilepsy, first degree family history of unprovoked seizure was significantly associated with clinical cut-offs for Total Problems and Internalizing Disorders. Among Internalizing Disorders, clinical cut-offs for Withdrawn/Depressed, and DSM-Oriented scales for Affective Disorder and Anxiety Disorder were significantly associated with family history of unprovoked seizures. Clinical cut-offs for Aggressive Behavior and Delinquent Behavior, and DSM-Oriented scales for Conduct Disorder and Oppositional Defiant Disorder were significantly associated with family history of unprovoked seizure. Adjustment for siblings with the same disorder revealed significant associations for the relationship between first degree family history of unprovoked seizure and Total Problems and Agressive Behavior in probands with uncomplicated epilepsy; marginally significant results were seen for Internalizing Disorder, Withdrawn/Depressed and Anxiety Disorder.
There was no association between family history of unprovoked seizure and behavioral problems in probands with complicated epilepsy. First degree family history of febrile seizure was not associated with behavioral problems in probands with uncomplicated or in those with complicated epilepsy.
Increased occurrence of behavioral disorders in probands with uncomplicated epilepsy and first degree family history of unprovoked seizure suggests familial clustering of these disorders. This supports the idea that behavioral disorders may be another manifestation of the underlying pathophysiology involved in epilepsy or closely related to it.
epilepsy; psychiatric disorders; family history; epidemiology
Children with epilepsy are usually treated with antiepileptic drugs (AEDS). Some AEDs adversely affect behavior in susceptible children. Since psychiatric comorbidity is prevalent in pediatric epilepsy, this paper attempts to disentangle these AED side effects from the psychopathology associated with this illness. It first outlines the clinical and methodological problems involved in determining if AEDs contribute to the behavior and emotional problems of children with epilepsy. It then presents research evidence for and against the role AEDs play in the psychopathology of children with epilepsy, and outlines how future studies might investigate this problem. A brief description of how to clinically separate out AED effects from the complex illness-related and psychosocial factors that contribute to the behavior difficulties of children with epilepsy concludes the paper.
antiepileptic drugs; epilepsy; psychopathology; children
Although magnetic resonance spectroscopy has identified metabolic abnormalities in adult and childhood schizophrenia, no prior studies have investigated the relationship between neurometabolites and thought disorder. This study examined this association in language-related brain regions using proton magnetic resonance spectroscopic imaging (1H MRSI).
MRSI was acquired bilaterally from 28 youth with childhood-onset schizophrenia and 34 healthy control subjects in inferior frontal, middle frontal, and superior temporal gyri at 1.5 T and short echo time (TR/TE=1500/30 ms). CSF-corrected “total NAA” (tNAA; N-acetyl-aspartate+N-acetyl-aspartyl-glutamate), glutamate+glutamine (Glx), creatine+phosphocreatine (Cr+PCr), choline compounds (Cho), and myo-inositol (mI) were assayed in manually drawn regions-of-interest partitioned into gray matter, white matter, and CSF and then coregistered with MRSI. Speech samples of all subjects were coded for thought disorder.
In the schizophrenia group, the severity of formal thought disorder correlated significantly with tNAA in the left inferior frontal and superior temporal gyri and with Cr+PCr in left superior temporal gyrus.
Neurometabolite concentrations in language-related brain regions are associated with thought disorder in childhood-onset schizophrenia.
Childhood-onset schizophrenia; Thought Disorder; Magnetic Resonance Spectroscopy; N-acetyl aspartate; Choline compounds
We compared associations of epilepsy remission status and severity as well as psychiatric and other comorbidities with child and parent-proxy reports of health-related quality of life (HRQoL) in adolescents previously diagnosed with epilepsy.
In a prospective, community-based study of newly diagnosed childhood epilepsy, HRQoL of 277 children was assessed 8 to 9 years after diagnosis by using child and parent-proxy versions of the Child Health Questionnaire (CHQ). Multiple linear regression models adjusted for age and gender were used to compare associations of epilepsy remission and “complicated” epilepsy (secondary to an underlying neurologic insult or epileptic encephalopathy) status and psychiatric and other comorbidities with HRQoL.
Mean age of epilepsy onset was 4.4 years (SD: 2.6). At the 9-year reassessment, children were, on average, 13.0 years old (SD: 2.6); 64% were seizure-free for 5 years, 31% were taking antiepileptic drugs, and 19% had a complicated epilepsy. Prevalence of comorbidities at follow-up were 26% psychiatric diagnosis; 39% neurodevelopmental spectrum disorder (NDSD); 24% chronic medical illness; and 15% migraine. In multivariable analysis, having a psychiatric disorder was broadly associated with child (6 of 11 scales) and parent-proxy (7 of 12 scales) HRQoL (P ≤ .0125). Five-year remission and complicated epilepsy status had few or no associations with HRQoL. Although parent-proxy HRQoL was strongly associated with NDSD (6 of 11 scales), child-reported HRQoL was not (2 of 11 scales).
Psychiatric comorbidities are strongly associated with long-term HRQoL in childhood-onset epilepsy, which suggests that comprehensive epilepsy care must include screening and treatment for these conditions, even if seizures remit.
epilepsy; psychiatric comorbidity; quality of life; Child Health Questionnaire; child and adolescent health
Subjects with autism suffer from impairments of social interaction, deviations in language usage, as well as restricted and stereotyped patterns of behavior. These characteristics are found irrespective of age, IQ and gender of affected subjects. However, brain changes due to age, IQ and gender may pose potential confounds in autism neuroimaging analyses.
To investigate grey matter differences in autism that are not related to these potential confounds, we performed a VBM analysis in 52 affected children and adolescents and 52 matched control subjects.
We observed diminished grey matter in a region of the hypothalamus, which synthesizes the behaviorally relevant hormones oxytocin and arginine vasopressin.
This finding provides support for further investigations of the theory of abnormal functioning of this hormonal system in autism and potentially for experimental therapeutic approaches using oxytocin and related neuropeptides.
ASD; VBM; children; adolescents; oxytocin; morphometry
Prior studies on healthy children have demonstrated regional variations and a complex and dynamic relationship between intelligence and cerebral tissue. Yet, there is little information regarding the neuroanatomical correlates of general intelligence in children with epilepsy compared to healthy controls. In vivo imaging techniques, combined with methods for advanced image processing and analysis, offer the potential to examine quantitative mapping of brain development and its abnormalities in childhood epilepsy. A surface-based, computational high resolution 3-D magnetic resonance image analytic technique was used to compare the relationship of cortical thickness with age and intelligence quotient (IQ) in 65 children and adolescents with complex partial seizures (CPS) and 58 healthy controls, aged 6 -18 years. Children were grouped according to health status (epilepsy; controls) and IQ level (average and above; below average) and compared on age-related patterns of cortical thickness. Our cross-sectional findings suggest that disruption in normal age-related cortical thickness expression is associated with intelligence in pediatric CPS patients both with average and below average IQ scores.
Cortical morphometry; IQ; complex partial seizures; cortical thickness; development; childhood
Given the fundamental role of thought disorder in schizophrenia, subtle communication disturbance may be a valuable predictor of subsequent development of psychosis. Here we examined the contribution of thought and communication disturbance to the prediction of outcome in adolescents identified as putatively prodromal for psychosis.
Transcribed speech samples were elicited from 105 adolescents (54 identified as being at clinical high risk for a first episode of psychosis (CHR) and 51 demographically comparable comparison subjects) and coded for formal thought disorder (FTD) and linguistic cohesion. We then examined the association of baseline FTD/cohesion with conversion to psychosis and social and role outcome at follow-up, approximately one year later.
At baseline, CHR patients who subsequently converted to psychosis (CHR+) showed an elevated rate of illogical thinking and poverty of content (POC) in their speech, relative to both typically developing controls and non-converters (CHR−). CHR+ youth also used significantly less referential cohesion at baseline, indicating that they provide fewer references to people, objects, or events mentioned in preceding utterances. Multiple regression models indicated that, among measures of FTD/cohesion, illogical thinking was uniquely predictive of subsequent conversion to psychosis, whereas POC and referential cohesion were significant predictors of social and role functioning, respectively.
Despite the absence of fully psychotic symptoms, putatively prodromal individuals evidence signs of communication disturbance that are qualitatively similar to those seen in schizophrenia, and are predictive of both conversion to psychosis and psychosocial outcome. These findings suggest that FTD measures have prognostic significance for at-risk youth.
thought disorder; psychosis prodrome; schizophrenia; language; psychosocial outcome
Epilepsy is a prevalent childhood neurological disorder, but there are few prospective quantitative magnetic resonance imaging studies examining patterns of brain development compared to healthy controls. Controlled prospective investigations initiated at or near epilepsy onset would best characterize the nature, timing and course of neuroimaging abnormalities in paediatric epilepsy. In this study, we report the results of a deformation-based morphometry technique to examine baseline and 2-year prospective neurodevelopmental brain changes in children with new and recent onset localization-related epilepsies (n = 24) and idiopathic generalized epilepsies (n = 20) compared to healthy controls (n = 36). Children with epilepsy demonstrated differences from controls in baseline grey and white matter volumes suggesting antecedent anomalies in brain development, as well as abnormal patterns of prospective brain development that involved not only slowed white matter expansion, but also abnormalities of cortical grey matter development involving both greater and lesser volume changes compared to controls. Furthermore, abnormal neurodevelopmental changes extended outside the cortex affecting several subcortical structures including thalamus, cerebellum, brainstem and pons. Finally, there were significant differences between the epilepsy syndromes (localization-related epilepsies and idiopathic generalized epilepsies) with the idiopathic generalized epilepsies group showing a more disrupted pattern of brain structure both at baseline and over the 2-year interval.
MRI; prospective neurodevelopment changes; deformation-based morphometry; new and recent onset epilepsy; localization-related epilepsy; idiopathic generalized epilepsy
Childhood-onset epilepsy is associated with psychiatric and cognitive difficulties and with poor social outcomes in adulthood. In a prospective cohort of young people with epilepsy, we studied psychiatric and neurodevelopmental disorders (PD and ND) and epilepsy-related characteristics, all factors which may influence long-term social outcomes. 501 subjects, 159 with complicated (IQ<80 or brain lesion) and 342 with uncomplicated epilepsy were included. PD and ND were more common in complicated epilepsy (p<0.005). In uncomplicated epilepsy, externalizing but not internalizing disorders were strongly associated with ND. Internalizing disorders and ND were associated with lack of 5-year remission. Type of epilepsy was not associated with NDs or PDs. Various comorbid conditions in epilepsy cluster together and are modestly associated with imperfect seizure control. These need to be considered together in evaluating and managing young people with epilepsy and may help explain long-term social outcomes above and beyond poor seizure control.
Co-morbidity; neurodevelopmental disorders; psychiatric disorders; epilepsy; childhood
Children with epilepsy and control children were followed over a two year interval. Comorbidities of epilepsy, often defined as problems related to IQ, academic achievement, language, and psychopathology, were evaluated prospectively. It was hypothesized that over time a) the presence of comorbidities would predict worse outcomes, and b) epilepsy variables would negatively impact comorbidities. The study included 39 children with complex partial seizures (CPS), 25 children childhood absence epilepsy (CAE), and 27 healthy children, aged 7.6-16.1 years. The findings were notable for stability over the interval in all three groups. Additionally, baseline seizure variables and change over the interval appear to play a role in IQ and math achievement scores of children with epilepsy with average IQ and in the reading achievement scores of those with below average IQ. However, seizures variables at baseline and follow-up were not predictors of DSM-IV diagnoses, depression, anxiety or behavioral problems.
Pediatric Epilepsy; academic achievement; cognition; language; psychopathology; prospective study
In this study, we used surface-based morphometry to examine whether age-related changes in gray matter tissue thickness and depth of sulcal regions at high spatial resolution across the cortex differed in children with childhood absence epilepsy (CAE) compared to healthy control subjects. In addition, the possibility of variable brain-cognition relationships in the CAE compared to the control group was investigated. The main findings of this study are as follows: (1) From the developmental perspective, children with CAE did not demonstrate the normal regional age-related changes involving a decrease in cortical thickness and increase in sulcal depth. (2) None of the seizure variables, including age of onset, seizure frequency, and AEDs had a significant effect on the association between age and cortical morphometry measures in the CAE population. (3) Even though the CAE group had mean VIQ and PIQ scores in the average range, our findings suggest that they use different brain regions to perform these cognitive functions compared to healthy controls. This first study on brain morphometry and cognition in children with childhood absence seizures has important implications for advancing our understanding of brain development and cognitive comorbidity in CAE, as well as for revisiting the clinical notion that CAE is a benign disorder.
Cortical morphometry; childhood absence epilepsy; IQ; cortical thickness; sulcal depth; development; cognition; generalized linear model
This study compared the relationship of language skill with fronto-temporal volumes in 69 medically treated epilepsy subjects and 34 healthy children, aged 6.1-16.6 years. It also determined if the patients with linguistic deficits had abnormal volumes and atypical associations between volumes and language skills in these brain regions. The children underwent language testing and magnetic resonance imaging scans at 1.5 Tesla. Brain tissue was segmented and fronto-temporal volumes were computed. Higher mean language scores were significantly associated with larger inferior frontal gyrus, temporal lobe, and posterior superior temporal gyrus gray matter volumes in the epilepsy group and in the children with epilepsy with average language scores. Increased total brain and dorsolateral prefrontal gray and white matter volumes, however, were associated with higher language scores in the healthy controls. Within the epilepsy group, linguistic deficits were related to smaller anterior superior temporal gyrus gray matter volumes and a negative association between language scores and dorsolateral prefrontal gray matter volumes. These findings demonstrate abnormal development of language related brain regions, and imply differential reorganization of brain regions subserving language in children with epilepsy with normal linguistic skills and in those with impaired language.
Language; epilepsy; development; MRI; frontal lobe; temporal lobe
Language processing abnormalities are a hallmark feature of schizophrenia. Yet, no study to date has investigated underlying neural networks associated with discourse processing in adolescents at clinical high risk (CHR) for developing psychosis.
Forty CHR youth and 24 demographically comparable healthy controls underwent functional magnetic resonance imaging while performing a naturalistic discourse processing paradigm. We assessed differences in blood oxygenation level-dependent (BOLD) activity between task conditions (Topic Maintenance vs. Reasoning) and between groups. Furthermore, we examined the association of regional brain activity with symptom severity and social outcome at follow-up, 6 to 24 months after the scan.
Relative to controls, CHR participants showed increased neural activity in a network of language-associated brain regions, including the medial prefrontal cortex bilaterally, left inferior frontal (LIFG; BA44/45, 47) and middle temporal gyri, and the anterior cingulate (BA24&32). Further, increased activity in the superior temporal gyrus (STG), caudate, and LIFG distinguished those who subsequently developed psychosis. Within the CHR sample, severity of positive formal thought disorder at follow-up was positively correlated with signal change in the LIFG, superior frontal gyrus, and inferior/middle temporal gyri, whereas social outcome was inversely correlated with signal change in the LIFG and anterior cingulate.
These findings are consistent with a neural inefficiency hypothesis in those at greatest risk for psychosis, and additionally suggest that baseline activation differences may predict symptomatic and functional outcome. These results highlight the need to further investigate the neural systems involved in conversion to psychosis, and how language disruption changes over time in at-risk adolescents.
fMRI; schizophrenia; inferior frontal gyrus; psychosis prodrome; discourse; functional neuroimaging
Previous magnetic resonance imaging (MRI)-based volumetric studies have shown age-related increases in the volume of total white matter and decreases in the volume of total gray matter of normal children. Recent adaptations of image analysis strategies enable the detection of human brain growth with improved spatial resolution. In this article, we further explore the spatio-temporal complexity of adolescent brain maturation with tensor-based morphometry. By utilizing a novel non-linear elastic intensity-based registration algorithm on the serial structural MRI scans of 13 healthy children, individual Jacobian growth maps are generated and then registered to a common anatomical space. Statistical analyses reveal significant tissue growth in cerebral white matter, contrasted with gray matter loss in parietal, temporal, and occipital lobe. In addition, a linear regression with age and gender suggests a slowing down of the growth rate in regions with the greatest white matter growth. We demonstrate that a tensor-based Jacobian map is a sensitive and reliable method to detect regional tissue changes during development.
brain development; Jacobian; longitudinal; MRI; nonlinear image registration; TBM
This cross-sectional study sought to confirm the presence and regional profile of previously reported changes in laminar cortical thickness in children and adolescents with Attention Deficit / Hyperactivity Disorder (ADHD) compared to typically developing healthy subjects.
High-resolution MR images were obtained from 22 (19 male, 3 female; mean age: 11.7 years) children and adolescents with ADHD and 22 age and sex matched healthy control subjects (mean age: 11.7 years). Brain tissue volumes were estimated for each subject. Cortical pattern matching methods were used to sample measures of laminar thickness at high spatial frequency across homologous regions of cortex. Volume and thickness measures were compared across diagnostic groups with and without controlling for general intelligence. False discovery rate (FDR) correction confirmed regional results.
Subjects with ADHD exhibited significant reductions in overall brain volume, gray matter volume and mean cortical thickness compared to healthy controls, while white matter volumes were significantly increased in ADHD. Highly significant cortical thinning (FDR-corrected p < .0006) was observed over large areas of frontal, temporal, parietal and occipital association cortices and aspects of motor cortex, but not within primary sensory regions.
Cortical thickness reductions present a robust neuroanatomical marker for child and adolescent ADHD. Observations of widespread cortical thinning expand upon earlier cross-sectional findings and provide further evidence to support that the neurobiological underpinnings of ADHD extend beyond prefrontal and subcortical circuits.
gray matter thickness; structural imaging
We used diffusion tensor imaging to investigate fractional anisotropy (FA), a measure of fiber tract integrity, in attention-deficit hyperactivity disorder (ADHD). Using a tract-based atlasing approach on six-direction diffusion tensor imaging data, we examined FA within the cingulum, corpus callosum, corticospinal tract, fornix, optic radiations, superior longitudinal fasciculus, uncinate fasciculus, and the superior and inferior occipitofrontal fasciculi in an all-male sample of17 children and adolescents with ADHD and 16 age-matched controls. ADHD patients had significantly lower FA in the corticospinal tract (P=0.02) and the superior longitudinal fasciculus (P=0.017) compared with controls. Results support that disruptions in motor and attentional networks may contribute toward ADHD pathophysiology. Future research may clarify how ADHD subtype and psychiatric comorbidities affect diffusion measures.
corticospinal tract; diffusion tensor imaging; fractional anisotropy; superior longitudinal fasciculus
The aim of this study was to determine if volumes of frontotemporal regions associated with language were related to thought disorder in 42 children, aged 5–16 years, with cryptogenic epilepsy, all of whom had complex partial seizures (CPS). The children with CPS and 41 age- and gender-matched healthy children underwent brain MRI scans at 1.5 T. Tissue was segmented, and total brain, frontal lobe, and temporal lobe volumes were computed. Thought disorder measures, IQ, and seizure information were collected for each patient. The subjects with CPS had more thought disorder, smaller total gray matter and orbital frontal gray matter volumes, as well as larger temporal lobe white matter volumes than the control group. In the CPS group, thought disorder was significantly related to smaller orbital frontal and inferior frontal gray matter volumes, increased Heschl’s gyrus gray matter volumes, and smaller superior temporal gyrus white matter volumes. However, significantly larger orbital frontal gyrus, superior temporal gyrus, and temporal lobe gray matter volumes and decreased Heschl’s gyrus white matter volumes were associated with thought disorder in the control group. These findings suggest that thought disorder might represent a developmental disability involving frontotemporal regions associated with language in pediatric CPS.
Thought disorder; Complex partial seizures; Development; Brain volumes; Childhood; Language
Depression represents one of the most common comorbidities in patients with epilepsy. However, the mechanisms of depression in epilepsy patients are poorly understood. Establishment of animal models of this comorbidity is critical for both understanding the mechanisms of the condition, and for preclinical development of effective therapies. The current study examined whether a commonly used animal model of temporal lobe epilepsy (TLE) is characterized by behavioural and biochemical alterations involved in depression. Male Wistar rats were subjected to LiCl and pilocarpine status epilepticus (SE). The development of chronic epileptic state was confirmed by the presence of spontaneous seizures and by enhanced brain excitability. Post-SE animals exhibited increase in immobility time under conditions of forced swim test (FST) which was indicative of despair-like state, and loss of taste preference in saccharin solution consumption test which pointed to the symptomatic equivalence of anhedonia. Biochemical studies revealed compromised serotonergic transmission in the raphe-hippocampal serotonergic pathway: decrease of serotonin (5-HT) concentration and turnover in the hippocampus, measured by high performance liquid chromatography, and decrease of 5-HT release from the hippocampus in response to raphe stimulation, measured by fast cyclic voltammetry. Administration of fluoxetine (FLX, 20 mg/kg/day for 10 days) to naive animals significantly shortened immobility time under conditions of FST, and inhibited 5-HT turnover in the hippocampus. In post-SE rats FLX treatment led to a further decrease of hippocampal 5-HT turnover; however, performance in FST was not improved. At the same time, FLX reversed SE-induced increase in brain excitability. In summary, our studies provide initial evidence that post-SE model of TLE might serve as a model of the comorbidity of epilepsy and depression. The finding that behavioural equivalents of depression were resistant to an antidepressant medication suggested that depression in epilepsy might have distinct underlying mechanisms beyond alterations in serotonergic pathways.
comorbidity; depression; epilepsy; hippocampus; serotonin