Identical neural risk factors predict cognitive deficit in dyslexia and schizophrenia

Eye movements and the perceptual span in disordered reading: A comparison of schizophrenia and dyslexia

Increasing evidence of a common neurodevelopmental etiology between schizophrenia and developmental dyslexia suggests that neurocognitive functions, such as reading, may be similarly disrupted. However, direct comparisons of reading performance in these disorders have yet to be conducted. To address this gap in the literature, we employed a gaze-contingent moving window paradigm to examine sentence-level reading fluency and perceptual span (breadth of parafoveal processing) in adults with schizophrenia (dataset from Whitford et al., 2013) and psychiatrically healthy adults with dyslexia (newly collected dataset). We found that the schizophrenia and dyslexia groups exhibited similar reductions in sentence-level reading fluency (e.g., slower reading rates, more regressions) compared to matched controls. Similar reductions were also found for standardized language/reading and executive functioning measures. However, despite these reductions, the dyslexia group exhibited a larger perceptual span (greater parafoveal processing) than the schizophrenia group, potentially reflecting a disruption in normal foveal-parafoveal processing dynamics. Taken together, our findings suggest that reading and reading-related functions are largely similarly disrupted in schizophrenia and dyslexia, providing additional support for a common neurodevelopmental etiology.

History of learning disorders is associated with worse cognitive and functional outcomes in schizophrenia: results from the multicentric FACE-SZ cross-sectional dataset

Schizophrenia is associated with early neurodevelopmental disorders, including most frequently learning disorders (LD), among them dyslexia and dyspraxia. Despite the demonstrated links between schizophrenia and LD, specific clinical patterns of the schizophrenia with a history of LD subgroup remain unknown. The aim of the present study was to investigate cognitive impairment, symptoms and functional outcome associated with a history of LD in a large cross-sectional, multicentric, sample of schizophrenia subjects. 492 community-dwelling subjects with schizophrenia (75.6% male, mean age 30.8 years) were consecutively included in the network of the FondaMental Expert Centers for Schizophrenia in France and received a thorough clinical assessment. The 51 (10.4%) subjects identified with a history of LD had significantly impaired general cognitive ability (Wechsler Adult Intelligence Scale Full Scale Total IQ: Cohen's d = 0.50, p = 0.001), processing speed (d = 0.19), verbal comprehension (d = 0.29), working memory (d = 0.31), cognitive inhibition and flexibility (d = 0.26), central executive functioning (d = 0.26), phonemic verbal fluency (d = 0.22) and premorbid intellectual ability (d = 0.48), as well as with a worse functional outcome (Global Assessment of Functioning, d = 0.21), independently of age, sex, education level, symptoms, treatments, and addiction comorbidities. These results indicate that a history of LD is associated with later cognitive impairment and functional outcome in schizophrenia. This suggests that history of LD is a relevant clinical marker to discriminate subgroups of patients with schizophrenia with different profiles in a precision psychiatry framework.

A Scoping Review on Movement, Neurobiology and Functional Deficits in Dyslexia: Suggestions for a Three-Fold Integrated Perspective

Developmental dyslexia is a common complex neurodevelopmental disorder. Many theories and models tried to explain its symptomatology and find ways to improve poor reading abilities. The aim of this scoping review is to summarize current findings and several approaches and theories, focusing on the interconnectedness between motion, emotion and cognition and their connection to dyslexia. Consequently, we present first a brief overview of the main theories and models regarding dyslexia and its proposed neural correlates, with a particular focus on cerebellar regions and their involvement in this disorder. After examining different types of intervention programs and remedial training, we highlight the effects of a specific structured sensorimotor intervention named Quadrato Motor Training (QMT). QMT utilizes several cognitive and motor functions known to be relevant in developmental dyslexia. We introduce its potential beneficial effects on reading skills, including working memory, coordination and attention. We sum its effects ranging from behavioral to functional, structural and neuroplastic, especially in relation to dyslexia. We report several recent studies that employed this training technique with dyslexic participants, discussing the specific features that distinguish it from other training within the specific framework of the Sphere Model of Consciousness. Finally, we advocate for a new perspective on developmental dyslexia integrating motion, emotion and cognition to fully encompass this complex disorder.

Automatic Schizophrenia Detection Using Multimodality Media via a Text Reading Task

Schizophrenia is a crippling chronic mental disease that affects people worldwide. In this work, an automatic schizophrenia detection algorithm is proposed based on the reading deficit of schizophrenic patients. From speech and video modalities, the automatic schizophrenia detection algorithm illustrates abnormal speech, head movement, and reading fluency during the reading task. In the speech modality, an acoustic model of speech emotional flatness in schizophrenia is established to reflect the emotional expression flatness of schizophrenic speech from the perspective of speech production and perception. In the video modality, the head-movement-related features are proposed to illustrate the spontaneous head movement caused by repeated reading and unconscious movement, and the reading-fluency-related features are proposed to convey the damaged degree of schizophrenic patients' reading fluency. The experimental data of this work are 160 segments of speech and video data recorded by 40 participants (20 schizophrenic patients and 20 normal controls). Combined with support vector machines and random forest, the accuracy of the proposed acoustic model, the head-movement-related features, and the reading-fluency-related features range from 94.38 to 96.50%, 73.38 to 83.38%, and 79.50 to 83.63%, respectively. The average accuracy of the proposed automatic schizophrenia detection algorithm reaches 97.50%. The experimental results indicate the effectiveness of the proposed automatic detection algorithm as an auxiliary diagnostic method for schizophrenia.

Dyslexia: Links with schizotypy and neurological soft signs

Abnormalities in language processing, psychological distress, and subtle neurodevelopmental features called neurological soft signs (NSS) are expressed by people with dyslexia and those scoring highly on schizotypy. We investigated whether the expression of NSS, distress, and schizotypy predicted dyslexia status. Participants (N = 96, 48 dyslexic) selected to be age and sex matched, completed the Schizotypal Personality Questionnaire, General Health Questionnaire, Neurological Evaluation Scale, and the National Adult Reading Test (NART; a measure of verbal intelligence). Dyslexia status was predicted by higher total NSS and disorganized schizotypy scores in the absence of NART. However, even with the inclusion of NART, disorganized schizotypy remained a significant predictor. The findings suggest that disorganized features of schizotypy could be a significant factor for those with dyslexia. Conversely, more attention needs to be given to developmental language disorders in those who score highly on schizotypy.

Reading skills deficits in people with mental illness: A systematic review and meta-analysis

BACKGROUND

Good reading skills are important for appropriate functioning in everyday life, scholastic performance, and acquiring a higher socioeconomic status. We conducted the first systematic review and meta-analysis to quantify possible deficits in specific reading skills in people with a variety of mental illnesses, including personality disorders (PDs).

METHODS

We performed a systematic search of multiple databases from inception until February 2020 and conducted random-effects meta-analyses.

RESULTS

The search yielded 34 studies with standardized assessments of reading skills in people with one or more mental illnesses. Of these, 19 studies provided data for the meta-analysis. Most studies (k = 27; meta-analysis, k = 17) were in people with schizophrenia and revealed large deficits in phonological processing (Hedge's g = -0.88, p < 0.00001), comprehension (Hedge's g = -0.96, p < 0.00001) and reading rate (Hedge's g = -1.22, p = 0.002), relative to healthy controls; the single-word reading was less affected (Hedge's g = -0.70, p < 0.00001). A few studies in affective disorders and nonforensic PDs suggested weaker deficits (for all, Hedge's g < -0.60). In forensic populations with PDs, there was evidence of marked phonological processing (Hedge's g = -0.85, p < 0.0001) and comprehension deficits (Hedge's g = -0.95, p = 0.0003).

CONCLUSIONS

People with schizophrenia, and possibly forensic PD populations, demonstrate a range of reading skills deficits. Future studies are needed to establish how these deficits directly compare to those seen in developmental or acquired dyslexia and to explore the potential of dyslexia interventions to improve reading skills in these populations.

Visual expertise for print in schizophrenia: Analysis of the N170 component

Reading deficits have been reported for patients suffering from schizophrenia namely, specific phonological processing deficits. Phonological processing skills are crucial in the learning-to-read process as they are necessary to develop visual expertise for print, which reflects the neural specialization for print. The present study is the first to test visual expertise for print in patients suffering from schizophrenia by measuring the N170 component. Patients and pair-matched healthy control participants performed a lexical decision task, in which words and symbols were presented. As expected, larger N170 amplitudes to word than to control stimuli were observed at the left occipito-temporal site PO7 but not at the PO8. More importantly, the modulation of the N170 as a function of the stimulus and hemisphere did not vary between patients and controls. This result suggests preserved visual expertise for print processing in patients suffering from schizophrenia.

Reading deficits in schizophrenia and their relationship to developmental dyslexia: A review

Although schizophrenia and developmental dyslexia are considered distinct disorders in terms of clinical presentation and functional outcome, they both involve disruption in the processes that support skilled reading, including language, auditory perception, visual perception, oculomotor control, and executive function. Further, recent work has proposed a common neurodevelopmental basis for the two disorders, as suggested by genetic and pathophysiological overlap. Thus, these lines of research suggest that reading may be similarly impacted in schizophrenia and dyslexia. In this review, we survey research on reading abilities in individuals with schizophrenia, and review the potential mechanisms underlying reading deficits in schizophrenia that may be shared with those implicated in dyslexia. Elucidating the relationship between reading impairment in schizophrenia and dyslexia could allow for a better understanding of the pathophysiological underpinnings of schizophrenia, and could facilitate remediation of cognitive deficits that impact day-to-day functioning.

Ten questions about terminology for children with unexplained language problems

BACKGROUND

In domains other than language, there is fairly consistent diagnostic terminology to refer to children's developmental difficulties. For instance, the terms 'dyslexia', 'attention deficit hyperactivity disorder' and 'autistic spectrum disorder' are used for difficulties with reading, attention or social cognition, respectively. There is no agreed label, however, for children with unexplained language problems.

AIMS

To consider whether we need labels for unexplained language problems in children, and if so, what terminology is appropriate.

MAIN CONTRIBUTION

There are both advantages and disadvantages to labels, but they are important to ensure children receive services, and to increase our knowledge of the nature and causes of such problems. A survey of labels in current use found 132 different terms, 33 of which had 600 or more returns on Google Scholar between 1994 and 2013. Many of these labels were too general to be useful. Of the remainder, the term 'specific language impairment' was the most commonly used.

CONCLUSIONS

The current mayhem in diagnostic labels is unsustainable; it causes confusion and impedes research progress and access to appropriate services. We need to achieve consensus on diagnostic criteria and terminology. The DSM-5 term 'language disorder' is problematic because it identifies too wide a range of conditions on an internet search. One solution is to retain specific language impairment, with the understanding that 'specific' means idiopathic (i.e., of unknown origin) rather than implying there are no other problems beyond language. Other options are the terms 'primary language impairment', 'developmental language disorder' or 'language learning impairment'.

Distinct regions of the cerebellum show gray matter decreases in autism, ADHD, and developmental dyslexia

Differences in cerebellar structure have been identified in autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and developmental dyslexia. However, it is not clear if different cerebellar regions are involved in each disorder, and thus whether cerebellar anatomical differences reflect a generic developmental vulnerability or disorder-specific characteristics. To clarify this, we conducted an anatomic likelihood estimate (ALE) meta-analysis on voxel-based morphometry (VBM) studies which compared ASD (17 studies), ADHD (10 studies), and dyslexic (10 studies) participants with age-matched typically-developing (TD) controls. A second ALE analysis included studies in which the cerebellum was a region of interest (ROI). There were no regions of significantly increased gray matter (GM) in the cerebellum in ASD, ADHD, or dyslexia. Data from ASD studies revealed reduced GM in the inferior cerebellar vermis (lobule IX), left lobule VIIIB, and right Crus I. In ADHD, significantly decreased GM was found bilaterally in lobule IX, whereas participants with developmental dyslexia showed GM decreases in left lobule VI. There was no overlap between the cerebellar clusters identified in each disorder. We evaluated the functional significance of the regions revealed in both whole-brain and cerebellar ROI ALE analyses using Buckner and colleagues' 7-network functional connectivity map available in the SUIT cerebellar atlas. The cerebellar regions identified in ASD showed functional connectivity with frontoparietal, default mode, somatomotor, and limbic networks; in ADHD, the clusters were part of dorsal and ventral attention networks; and in dyslexia, the clusters involved ventral attention, frontoparietal, and default mode networks. The results suggest that different cerebellar regions are affected in ASD, ADHD, and dyslexia, and these cerebellar regions participate in functional networks that are consistent with the characteristic symptoms of each disorder.

Cerebellar function in developmental dyslexia

Developmental dyslexia is a genetically based neurobiological syndrome, which is characterized by reading difficulty despite normal or high general intelligence. Even remediated dyslexic readers rarely achieve fast, fluent reading. Some dyslexics also have impairments in attention, short-term memory, sequencing (letters, word sounds, and motor acts), eye movements, poor balance, and general clumsiness. The presence of "cerebellar" motor and fluency symptoms led to the proposal that cerebellar dysfunction contributes to the etiology of dyslexia. Supporting this, functional imaging studies suggest that the cerebellum is part of the neural network supporting reading in typically developing readers, and reading difficulties have been reported in patients with cerebellar damage. Differences in both cerebellar asymmetry and gray matter volume are some of the most consistent structural brain findings in dyslexics compared with good readers. Furthermore, cerebellar functional activation patterns during reading and motor learning can differ in dyslexic readers. Behaviorally, some children and adults with dyslexia show poorer performance on cerebellar motor tasks, including eye movement control, postural stability, and implicit motor learning. However, many dyslexics do not have cerebellar signs, many cerebellar patients do not have reading problems, and differences in dyslexic brains are found throughout the whole reading network, and not isolated to the cerebellum. Therefore, impaired cerebellar function is probably not the primary cause of dyslexia, but rather a more fundamental neurodevelopmental abnormality leads to differences throughout the reading network.

Evidence for the involvement of ZNF804A in cognitive processes of relevance to reading and spelling

Previous studies have shown that individuals with schizophrenia and dyslexia display common neurocognitive abnormalities. The aim of the present study was to determine whether known schizophrenia-risk genes contribute to dyslexia risk or to disease-relevant cognitive functions. For this purpose, we genotyped the schizophrenia-associated risk variants within zinc-finger protein 804A (ZNF804A), transcription-factor 4 and neurogranin in a large dyslexia case-control sample. We tested all variants for association with dyslexia (927 cases, 1096 controls), and with eight language-relevant cognitive processes (1552 individuals). We observed six significant associations between language-relevant traits and the ZNF804A-variant rs1344706. Interestingly, the ZNF804A schizophrenia risk variant was associated with a better cognitive performance in our data set. This finding might be consistent with a previously reported ZNF804A association in schizophrenia, in which patients carrying the schizophrenia-risk allele at rs1344706 showed a better performance in two memory tests. In conclusion, the present study provides evidence that ZNF804A might have a role in cognitive traits of relevance to reading and spelling, and underlines the phenotypic complexity that might be associated with ZNF804A.

Risk factors at the low end of the psychosis continuum: much the same as at the upper end?

We investigated risk factors for subclinical symptoms of psychosis, and focused on two psychosis dimensions previously identified in the Zurich Study, namely "schizophrenia nuclear symptoms" and "schizotypal signs". We examined the data from 9814 Swiss conscripts from 2003. The psychosis symptom dimensions were derived from the Symptom-Checklist-90-R (SCL-90-R), and were regressed on a broad range of known risk factors for psychosis. Risk factors typically assigned to schizophrenia and other psychotic disorders - cannabis use, childhood adversity, reading and writing difficulties, attention deficit hyperactivity disorder (ADHD), psychiatric disorders and addiction in parents and the extended family - are relevant also at subclinical levels. Our analyses suggested that specific risk factors may be assigned to distinct psychosis dimensions, as previously determined in an analysis from the Zurich Study. If there are different pathways to psychosis characterized by specific symptom dimensions and risk factors, they mostly co-exist and interact at different symptom load levels.

Genetic influences of cortical gray matter in language-related regions in healthy controls and schizophrenia

Individuals with schizophrenia show a broad range of language impairments, including reading difficulties. A recent structural MRI (sMRI) study linked these difficulties to structural abnormalities in language-related regions (Leonard et al., 2008). Similar regions have been implicated in primary reading disability (RD). Major hypotheses of RD implicate abnormal embryonic neuronal migration in the cortex, and genetic linkage and association studies have identified a number of candidate RD genes that are associated with neuronal migration (Paracchini et al., 2007). Interestingly, evidence suggests at least some individuals with schizophrenia also show impaired neuronal migration in the cortex (Akbarian et al., 1996). Thus the aim of this study was to examine the link between RD-related genes and gray matter volumes in healthy controls and schizophrenia. We used parallel independent component analysis (parallel-ICA) to examine the relationship between gray matter volumes extracted using voxel-based morphometry (VBM) and 16 single nucleotide polymorphisms (SNPs) spanning FOXP2 and four RD-related genes, DCDC2, DYX1C1, KIAA0319 and TTRAP. Parallel-ICA identified five sMRI-SNP relationships. Superior and inferior cerebellar networks were related to DYX1C1 and DCDC2/KIAA0319 respectively in both groups. The superior prefrontal, temporal and occipital networks were positively related to DCDC2 in the schizophrenia, but not the control group. The identified networks closely correspond to the known distribution of language processes in the cortex. Thus, reading and language difficulties in schizophrenia may be related to distributed cortical structural abnormalities associated with RD-related genes.

Cerebral asymmetry in schizophrenia

The hemispheres of the human brain are anatomically and functionally asymmetric, and many cognitive and motor functions such as language and handedness are lateralized. This review examines anatomical, psychological, and physiological approaches to the understanding of separate hemispheric functions and their integration. The concept of hemispheric laterality plays a central role in current neuropsychological and pathophysiological models of schizophrenia. Reduced hemispheric asymmetry has also been reported for other mental disorders, for example, bipolar disorder. Recent research reflects an increasing interest in the molecular and population genetics of laterality and its potential link with animal models of schizophrenia. The authors review the principles of laterality and brain asymmetry and discuss the evidence for changes in asymmetry in schizophrenia and other mental disorders.

Reduced laterality as a trait marker of schizophrenia--evidence from structural and functional neuroimaging

Laterality is a characteristic principle of the organization of the brain systems for language, and reduced hemispheric asymmetry has been considered a risk factor for schizophrenia. Here we sought support for the risk factor hypothesis by investigating whether reduced asymmetry of temporal lobe structure and function is also present in unaffected relatives. Sixteen schizophrenia patients, 16 age-matched first-degree relatives, and 15 healthy controls underwent high-resolution three-dimensional anatomical imaging and functional magnetic resonance imaging during auditory stimulation. Both the overall auditory cortex and planum temporale volumes and the lateralization to the left hemisphere were markedly reduced in patients. The decrease of lateralization correlated with increased severity of symptoms. In addition, both the overall functional activation in response to auditory stimulation and its asymmetry were reduced in the patients. Relatives had intermediate values between patients and controls on both structural and functional measures. This study provides added support for the idea that reduced hemispheric asymmetry is a biological risk factor for schizophrenia.

A large-scale investigation of lateralization in cortical anatomy and word reading: are there sex differences?

The authors report findings of a large-scale, multitask investigation of sex differences in both structural asymmetries and lateralization of word reading. Two hundred participants were tested in eight divided visual field lexical tasks, and each received a structural magnetic resonance imaging scan. The authors examined whether there was evidence for sex differences in overall measures of neuroanatomical and behavioral lateralization, in specific language tasks and brain regions, and in variation in asymmetry within and across tasks and brain regions. There was very little evidence for sex differences on any behavioral measure. The few indications of sex differences in the current report accounted for 2% or less of the individual variation in asymmetry and could not be replicated in independent subsamples. No sex differences were observed in the asymmetry of structures in Broca's and Wernicke's areas such as pars triangularis, pars opercularis, the planum temporale, planum parietale, or Heschl's gyrus. There were also no sex differences in the variability of neuroanatomical asymmetries within or between brain regions. However, a significant relationship between planum temporale and behavioral asymmetry was restricted to men.