Saccadic eye movement task identifies cognitive deficits in children with schizophrenia, but not in unaffected child relatives

Oculomotor, vestibular, reaction time, and cognitive (OVRT-C) responses in 7- to 17-year-old children

Several aspects of oculomotor, vestibular, reaction time, and cognitive (OVRT-C) abilities improve throughout childhood at varying rates and become adult-like at different ages. However, developmental testing of these abilities often focuses on limited age ranges and does not elucidate clear developmental trajectories. The present study utilized high-resolution eye-tracking to evaluate 40 children aged 7-17 years on a comprehensive battery of OVRT-C tests to better understand how and when these abilities develop across childhood. As expected, mean responses on OVRT-C tests showed consistent improvement as subject age increased. We report a high prevalence of saccadic intrusions during smooth pursuit in children and adolescents, more self-paced saccades in older children, decreased auditory and visual RT with age, and fewer errors on the anti-saccade test in older children. We also used the Akaike information criterion (AIC) and Bayesian information criterion (BIC) modelling to determine whether a two- or three age group division would be most appropriate for each OVRT-C test. For all key OVRT-C metrics, our data support a separation of children into two age groups as opposed to three. While the age group divide varied by OVRT-C test, these data suggest these abilities mature at differing rates, and optimal separations into two age groups rather than three may reflect a slowing of rapid development as OVRT-C performance becomes more adult-like.

Saccadic dysfunction in patients with hypoxic-ischemic encephalopathy

Electrophysiological monitoring of saccadic eye movements in patients with hypoxic-ischemic encephalopathy (HIE) was carried out. Externally guided saccades (prosaccades) were recorded using a patented hardware-software complex for studying the subject's physical activity. Recordings were performed in two independent experimental procedures - for saccades separately and when they were in coordination with the motion of head and hand. In both cases statistically significant differences in latent periods and durations of saccadic eye movements were noticed in HIE patients in comparison with healthy subjects of the same age group (p<0.05). Jerking and deviation of eyes after fixing the gaze on a target were often present in HIE participants. In some cases saccades of patients were asymmetrical among themselves. We found HIE induced changes in the parameters of autosaccades as well, expressed through the instability of gaze fixation periods, sometimes asymmetric eye movements, slow gaze shift from one target to another and disturbance of gaze stabilization (as jerking of the eyeballs during the saccadic period).

A Survey on Computer Vision for Assistive Medical Diagnosis From Faces

Automatic medical diagnosis is an emerging center of interest in computer vision as it provides unobtrusive objective information on a patient's condition. The face, as a mirror of health status, can reveal symptomatic indications of specific diseases. Thus, the detection of facial abnormalities or atypical features is at upmost importance when it comes to medical diagnostics. This survey aims to give an overview of the recent developments in medical diagnostics from facial images based on computer vision methods. Various approaches have been considered to assess facial symptoms and to eventually provide further help to the practitioners. However, the developed tools are still seldom used in clinical practice, since their reliability is still a concern due to the lack of clinical validation of the methodologies and their inadequate applicability. Nonetheless, efforts are being made to provide robust solutions suitable for healthcare environments, by dealing with practical issues such as real-time assessment or patients positioning. This survey provides an updated collection of the most relevant and innovative solutions in facial images analysis. The findings show that with the help of computer vision methods, over 30 medical conditions can be preliminarily diagnosed from the automatic detection of some of their symptoms. Furthermore, future perspectives, such as the need for interdisciplinary collaboration and collecting publicly available databases, are highlighted.

Insights to the schizophrenia continuum: A systematic review of saccadic eye movements in schizotypy and biological relatives of schizophrenia patients

Myles, J.B., S. Rossell, A. Phillipou, Thomas, E and C. Gurvich. A systematic review of saccadic eye movements across the schizophrenia continuum: Characterisation, pathophysiology and genetic associations. NEUROSCI BIOBEHAV REV 21(1) XXX-XXX, 2015. One of the cognitive hallmarks of schizophrenia is impaired eye movements, particularly for the antisaccade task. Less saccade research has been conducted in relation to the broader schizophrenia continuum, that is, people with high schizotypy or first-degree relatives of people with schizophrenia. This systematic review sought to identify, collate and appraise prosaccade, antisaccade and memory-guided saccade studies involving behavioural, neuroimaging and genetic data published between 1980 and September 2016 in individuals with high schizotypy and first-degree relatives. A systematic literature search was conducted, using Ovid MEDLINE, PsycINFO, PubMed and SCOPUS databases. Of 913 references screened, 18 schizotypy, 29 family studies and two schizotypy and relatives articles studies were eligible for inclusion. Antisaccade error rate was the most consistent deficit found for high schizotypy. Relatives had intermediate antisaccade error rates between patients and healthy controls. Results from the limited genetic and neuroimaging studies echoed schizophrenia findings. Confounds were also identified. It was concluded that future research is required to refine the saccade endophenotype and to expand genetic and neuroimaging research.

15q13.3 duplication in two patients with childhood-onset schizophrenia

We report two cases of paternally inherited 15q13.3 duplications in carriers diagnosed with childhood-onset schizophrenia (COS), a rare neurodevelopmental disorder of proposed polygenic origin with onset in children before age 13. This study documents that the 15q13.3 deletion and duplication exhibit pathogenicity for COS, with both copy number variants (CNVs) sharing a disrupted CHRNA7 gene. CHRNA7 encodes the neuronal alpha7 nicotinic acetylcholine receptor (α7nAChR) and is a candidate gene that has been suggested as a pathophysiological process mediating adult-onset schizophrenia (AOS) and other neurodevelopmental disorders. These results support the incomplete penetrance and variable expressivity of this CNV and represent the first report of 15q13.3 duplication carriers exhibiting COS. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics published by Wiley Periodicals, Inc.

Incidental threat during visuospatial working memory in adolescent anxiety: an emotional memory-guided saccade task

BACKGROUND

Pediatric anxiety disorders are among the most common psychiatric mental illnesses in children and adolescents, and are associated with abnormal cognitive control in emotional, particularly threat, contexts. In a series of studies using eye movement saccade tasks, we reported anxiety-related alterations in the interplay of inhibitory control with incentives, or with emotional distractors. The present study extends these findings to working memory (WM), and queries the interaction of spatial WM with emotional stimuli in pediatric clinical anxiety.

METHODS

Participants were 33 children/adolescents diagnosed with an anxiety disorder, and 22 age-matched healthy comparison youths. Participants completed a novel eye movement task, an affective variant of the memory-guided saccade task. This task assessed the influence of incidental threat on spatial WM processes during high and low cognitive load.

RESULTS

Healthy but not anxious children/adolescents showed slowed saccade latencies during incidental threat in low-load but not high-load WM conditions. No other group effects emerged on saccade latency or accuracy.

CONCLUSIONS

The current data suggest a differential pattern of how emotion interacts with cognitive control in healthy youth relative to anxious youth. These findings extend data from inhibitory processes, reported previously, to spatial WM in pediatric anxiety.

Memory-guided saccades in youth-onset psychosis and attention deficit hyperactivity disorder (ADHD)

AIM

Working memory deficits have been shown to be present in children and adolescents with schizophrenia and attention deficit hyperactivity disorder. Considering the differences in clinical characteristics between these disorders, it was the goal of this study to assess differences in the specific components of working memory in children and adolescents with psychosis and attention deficit hyperactivity disorder.

METHODS

Children and adolescents (age range 8-20 years) with either a non-affective psychotic disorder (n = 25), attention deficit hyperactivity disorder (n = 33) and controls (n = 58) were administered an oculomotor delayed-response task using both a recall and a control condition. Memory-guided saccades were measured during delay periods of 2, 8 and 20 s.

RESULTS

Although both clinical groups were less accurate than controls, there was no evidence of a disproportionate impairment in recall. In addition, there was no evidence of a delay-dependent impairment in psychosis; however, there was a delay-dependent impairment in attention deficit hyperactivity disorder when corrective saccades were included. Speed of information processing was correlated with distance errors in psychosis, suggesting that speed of encoding the stimulus location may have constrained the accuracy of the saccades.

CONCLUSIONS

Our findings support impairments during encoding in the psychosis group and a delay-dependent deficit in the attention deficit hyperactivity disorder group.

Neuropsychological functioning in childhood-onset psychosis and attention-deficit/hyperactivity disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) and childhood-onset psychosis (COP) are chronic, heterogeneous disorders with symptoms that frequently co-occur, but the etiology of their comorbidity is unknown. Studies of each disorder indicate that both ADHD and COP are associated with a range of neuropsychological weaknesses, but few neuropsychological studies have directly compared groups with ADHD and COP.

METHODS

Groups with ADHD only (32 F, 48 M), COP only (5 F, 5 M), ADHD + COP (9 F, 21 M), and a control group with neither disorder (25 F, 44 M) completed a neuropsychological battery that included measures of verbal working memory, response inhibition, response speed and variability, and selective attention.

RESULTS

All three clinical groups exhibited significantly lower performance versus the control group on all neuropsychological measures, whereas the only significant difference between the clinical groups was a significantly larger weakness in verbal working memory in the groups with COP.

CONCLUSIONS

The frequent co-occurrence between COP and ADHD may reflect shared neuropsychological weaknesses that are most pronounced on measures of working memory and response variability.

Comparison of alcohol impairment of behavioral and attentional inhibition

BACKGROUND

Despite the wealth of studies demonstrating the impairing effects of alcohol on behavioral inhibition, less is known regarding effects of the drug on attentional inhibition (i.e., the ability to ignore distracting stimuli in the environment in order to focus attention on relevant information). The current study examined alcohol impairment of both behavioral and attentional inhibition, as well as potential associations between the two mechanisms of inhibitory control.

METHODS

Men (n=27) and women (n=21) performed a measure of behavioral inhibition (cued go/no-go task) and a measure of attentional inhibition (delayed ocular return task) following three doses of alcohol: 0.65 g/kg, 0.45 g/kg, and 0.0 g/kg (placebo).

RESULTS

Alcohol impaired both behavioral and attentional inhibition relative to placebo; however, correlational analyses revealed no associations between measures of behavioral and attentional inhibition following any dose. Additionally, men committed more inhibitory failures on the behavioral inhibition task, whereas women committed more inhibitory failures on the attentional inhibition task.

CONCLUSIONS

These findings suggest that behavioral and attentional inhibition are equally sensitive to the impairing effects of alcohol, yet represent distinct components of inhibitory control. Additionally, the observed gender differences in control of behavior and attention could have important implications regarding negative consequences associated with alcohol-induced disinhibition in men and women.

Reduced prepulse inhibition as an early vulnerability marker of the psychosis prodrome in adolescence

BACKGROUND

The onset of psychosis is thought to be preceded by neurodevelopmental changes in the brain. However, the timing and nature of these changes have not been established. The aim of the present study was to determine whether three "classic" neurophysiological markers of schizophrenia are also characteristic of young adolescents (12-18 years) at ultra-high risk for psychosis (UHR).

METHODS

63 young UHR individuals and 68 typically developing, age-, sex- and IQ-matched controls were recruited for neurophysiological assessment. Data for P50 suppression, prepulse inhibition (PPI) and smooth pursuit eye movements (SPEM) were gathered and compared.

RESULTS

UHR individuals showed reduced PPI compared to controls, which became more pronounced when controls were directly compared to medication-naive UHR individuals (N=39). There were no group differences in P50 or SPEM measures.

CONCLUSIONS

These results suggest that PPI is a relatively early vulnerability marker, while changes in other neurophysiological measures may only be detected or affected later during the illness course. Antipsychotic and antidepressant medication may aid in elevating PPI levels and potentially have a neuroprotective effect.

Does response variability predict distractibility among adults with attention-deficit/hyperactivity disorder?

Increased intraindividual variability in response time (RTSD) has been observed reliably in attention-deficit/hyperactivity disorder (ADHD) and has often been used as a measure of inattention. RTSD is assumed to reflect attentional lapses and distractibility, though evidence for the validity of this connection is lacking. We assessed whether RTSD is an indicator of inattention by comparing RTSD on the stop-signal task (SST) with performance on the delayed oculomotor response (DOR) task, a measure of distractibility. Participants included 30 adults with ADHD and 28 controls. Participants completed the SST and the DOR task, which measured subjects' ability to maintain attention and avoid distraction by inhibiting reflexive saccades toward distractors. On the SST, the ADHD group was slower to inhibit than were controls, indicating poorer inhibitory control in ADHD. The ADHD group also displayed slower reaction times (RTs), greater RTSD, and more omission errors. On the DOR task, the ADHD group displayed more premature saccades (i.e., greater distractibility) than did controls. Greater variability in RT was associated with increased distraction on the DOR task, but only in ADHD participants. Results suggest that RTSD is linked to distractibility among adults with ADHD and support the use of RTSD as a valid measure of inattention in ADHD.

Separating automatic and intentional inhibitory mechanisms of attention in adults with attention-deficit/hyperactivity disorder

Researchers in the cognitive sciences recognize a fundamental distinction between automatic and intentional mechanisms of inhibitory control. The use of eye-tracking tasks to assess selective attention has led to a better understanding of this distinction in specific populations, such as children with attention-deficit/hyperactivity disorder (ADHD). This study examined automatic and intentional inhibitory control mechanisms in adults with ADHD using a saccadic interference task and a delayed ocular response task. Thirty adults with ADHD were evaluated against 27 comparison adults on measures of inhibitory control. The delayed ocular response task showed that adults with ADHD were less able than comparison adults to inhibit a reflexive saccade toward the sudden appearance of a stimulus in the periphery. However, saccadic interference task performance showed that the ADHD group did not differ significantly from the comparison group on a measure of automatic inhibitory control. These findings suggest a dissociation between automatic and intentional inhibitory deficits in adults with ADHD.

Behavioral components of impulsivity predict alcohol consumption in adults with ADHD and healthy controls

BACKGROUND

The degree to which distinct behavioral components of impulsivity predict alcohol consumption is as yet not well-understood. Further, the possibility that this relation might be more pronounced in groups characterized by heightened impulsivity (i.e., individuals with ADHD) has not been tested.

METHODS

The current study examined the degree to which three specific behavioral components of impulsivity (i.e., poor response inhibition, poor attentional inhibition, and increased risk-taking) were associated with quantity and frequency of alcohol consumption in a group of young adult social drinkers with ADHD (n = 33) and in a comparison control group (n = 21). Participants performed the delayed ocular return task (attentional inhibition), the cued go/no-go task (behavioral inhibition), and the balloon analogue risk task (risk-taking).

RESULTS

Both poor behavioral inhibition and greater risk-taking were related to greater quantity of consumption in the entire sample, whereas poor attentional inhibition was related to greater quantity specifically among those with ADHD. By contrast, only risk-taking was associated with frequency of consumption, and this was found specifically in the control group.

CONCLUSIONS

These findings provide important information regarding the potential role of distinct behavioral components of impulsivity in drinking behavior, and highlight unique relevance of attentional impairments to drinking behavior in those with ADHD.

Behavioral disinhibition: liability for externalizing spectrum disorders and its genetic and environmental relation to response inhibition across adolescence

Behavioral disinhibition has been characterized as a generalized vulnerability to externalizing disorders. Despite increasing evidence for its validity and heritability, the structural stability of behavioral disinhibition across adolescence and the strength and etiology of its relation to executive functions have not been studied. In this multivariate twin study, the authors assessed behavioral disinhibition using measures tapping substance use, conduct disorder, attention-deficit/hyperactivity disorder (ADHD), and novelty seeking at ages 12 and 17. Executive functions were assessed with laboratory-based cognitive tasks at age 17. Results indicated that, at age 12, behavioral disinhibition was dominated by ADHD and conduct problems and was highly heritable. At age 17, the contributions of the 4 components were more balanced, and the proportion of variance attributable to genetic factors was somewhat smaller, with additional variance due to shared environmental influences. At both ages, behavioral disinhibition was more closely related to response inhibition than other executive functions (working memory updating and task-set shifting), and this relationship was primarily genetic in origin. These results highlight the dynamic nature of behavioral disinhibition across adolescence and suggest that response inhibition may be an important mechanism underlying vulnerability to disinhibitory psychopathology.

A review on eye movement studies in childhood and adolescent psychiatry

The neural substrates of eye movement measures are largely known. Therefore, measurement of eye movements in psychiatric disorders may provide insight into the underlying neuropathology of these disorders. Visually guided saccades, antisaccades, memory guided saccades, and smooth pursuit eye movements will be reviewed in various childhood psychiatric disorders. The four aims of this review are (1) to give a thorough overview of eye movement studies in a wide array of psychiatric disorders occurring during childhood and adolescence (attention-deficit/hyperactivity disorder, oppositional deviant disorder and conduct disorder, autism spectrum disorders, reading disorder, childhood-onset schizophrenia, Tourette's syndrome, obsessive compulsive disorder, and anxiety and depression), (2) to discuss the specificity and overlap of eye movement findings across disorders and paradigms, (3) to discuss the developmental aspects of eye movement abnormalities in childhood and adolescence psychiatric disorders, and (4) to present suggestions for future research. In order to make this review of interest to a broad audience, attention will be given to the clinical manifestation of the disorders and the theoretical background of the eye movement paradigms.

Is familiality associated with downward occupation drift in schizophrenia?

OBJECTIVE

Downward occupational drift has been extensively investigated in schizophrenia. It is known that certain illness related factors, such as severity, affect drift, but the impact of familial factors has not been investigated.

METHODS

Occupation drift was studied among patients with schizophrenia/schizoaffective disorder (SZ/SZA)(n=523) and 130 affected sib pairs (ASPs). Drift was analyzed in relation to familiality as well as demographic and clinical variables. For comparison one proband (one of the affected siblings) from each ASP was selected. Occupation drift was measured in relation to the most responsible job held, and with regard to head of the household (HOH) occupation status.

RESULTS

There was no significant difference between single affected and ASP probands in terms of occupational drift from the most responsible job (drifted 39.2% and 38% respectively) and with regard to HOH's occupation (drifted 88% and 82.8% respectively). A significant part of the sample remained unemployed in both single affected and ASP samples. Thus, there was no significant impact of familiality on these variables. However, marital status, pattern of severity, age at onset, gender were found to be associated with downward occupation drift in single affected probands while the only significant factor in familial probands was pattern of severity of severity when measuring in terms of downward drift from most responsible job.

CONCLUSION

Though there is occupation drift in schizophrenia, there is no detectable impact of familial factors. Employment is associated with severity of delete.

Which perspectives can endophenotypes and biological markers offer in the early recognition of schizophrenia?

The early recognition of schizophrenia seems crucial; various studies relate a longer duration-of-untreated-psychosis to a worse prognosis. We give an overview over common psychopathological early recognition instruments (BSABS, CAARMS, SIPS, IRAOS, ERIraos). However, many clinical symptoms of prodromal schizophrenia stages are not sufficiently specific. Thus we review recent contributions of neuroimaging and electrophysiological as well as genetic studies: which new diagnostic perspectives offer endophenotypes (such as P300, P50 sensory gating, MMN, smooth pursuit eye movements; indicating a specific genetic vulnerability) together with a better understanding of schizophrenic pathophysiology (state-dependent biological markers, e.g. aggravated motor neurological soft signs during psychosis) in prodromal schizophrenia when still ambiguous clinical symptoms are present. Several examples (e.g. from COMT polymorphisms to working memory deficits) illustrate more specific underlying neuronal mechanisms behind behavioural symptoms. This way, a characteristic pattern of disturbed cerebral maturation might be distinguished in order to complement clinical instruments of early schizophrenia detection.

The endophenotype concept in psychiatric genetics

The idea that some phenotypes bear a closer relationship to the biological processes that give rise to psychiatric illness than diagnostic categories has attracted considerable interest. Much effort has been devoted to finding such endophenotypes, partly because it is believed that the genetic basis of endophenotypes will be easier to analyse than that of psychiatric disease. This belief depends in part on the assumption that the effect sizes of genetic loci contributing to endophenotypes are larger than those contributing to disease susceptibility, hence increasing the chance that genetic linkage and association tests will detect them. We examine this assumption by applying meta-analytical techniques to genetic association studies of endophenotypes. We find that the genetic effect sizes of the loci examined to date are no larger than those reported for other phenotypes. A review of the genetic architecture of traits in model organisms also provides no support for the view that the effect sizes of loci contributing to phenotypes closer to the biological basis of disease is any larger than those contributing to disease itself. While endophenotype measures may afford greater reliability, it should not be assumed that they will also demonstrate simpler genetic architecture.

High rates of comorbidity are found in childhood-onset schizophrenia

BACKGROUND

For adults with schizophrenia, comorbidity is common and contributes to impairment. Thus, there has been an increasing effort to identify and treat comorbid symptoms. This report extends that work by examining comorbidity in children and young adolescents with childhood-onset schizophrenia.

METHODS

Eighty-two children, ages 4-15 years, with schizophrenia or schizoaffective disorder received structured diagnostic instruments for symptoms and pharmacological treatment history. DSM-IV diagnoses were identified using a non-hierarchical approach.

RESULTS

Eighty-one (99%) of the children with schizophrenia or schizoaffective disorder had at least one comorbid psychiatric illness: attention deficit hyperactivity disorder (84%), oppositional defiant disorder (43%), depression (30%), and separation anxiety disorder (25%) were the most common comorbid conditions identified. Pharmacological treatment of the comorbid conditions was uncommon.

DISCUSSION

Comorbid syndromes are common in children and young adolescents with schizophrenia or schizoaffective disorder. Pharmacological treatment of the comorbid conditions is rare; however it is unclear if this is due to DSM-IVs hierarchical diagnostic system or to a lack of empirically driven guidelines for appropriate treatment. Additional efforts focused on comorbidity in very-early-onset schizophrenia are warranted.

Alcohol effects on inhibitory control of attention: distinguishing between intentional and automatic mechanisms

RATIONALE

Recent research has begun to explore the possibility that inhibitory mechanisms of selective attention are particularly susceptible to the impairing effects of moderate doses of alcohol. However, literature also suggests that automatic processes might be more resistant to this impairing effect than controlled processes.

OBJECTIVE

The present study used a delayed ocular response task and a saccadic interference task to examine the effects of alcohol on both intentionally controlled and automatic inhibitory influences on selective attention.

MATERIALS AND METHODS

Twelve healthy adults performed both tasks under three doses of alcohol (0.0, 0.45, and 0.65 g/kg).

RESULTS

The results showed that alcohol reduced intentional inhibitory control over selective attention but had no effect on automatic inhibitory influences.

CONCLUSION

The present investigation marks the first effort to directly compare alcohol effects on automatic and intentional inhibitory mechanisms of visual attention. The results suggest that attentional processes dependent on intentional inhibitory control may be more susceptible to the impairing effects of a moderate dose of alcohol than processes dependent on automatic inhibition.