A diagnostic model incorporating P50 sensory gating and neuropsychological tests for schizophrenia

Meta-analysis of auditory P50 sensory gating in schizophrenia and bipolar disorder

The ability of the brain to reduce the amount of trivial or redundant sensory inputs is called gating function. Dysfunction of sensory gating may lead to cognitive fragmentation and poor real-world functioning. The auditory dual-click paradigm is a pertinent neurophysiological measure of sensory gating function. This meta-analysis aimed to examine the subcomponents of abnormal P50 waveforms in bipolar disorder and schizophrenia to assess P50 sensory gating deficits and examine effects of diagnoses, illness states (first-episode psychosis vs. schizophrenia, remission vs. episodes in bipolar disorder), and treatment status (medication-free vs. medicated). Literature search of PubMed between Jan 1st 1980 and March 31st 2019 identified 2091 records for schizophrenia, 362 for bipolar disorder. 115 studies in schizophrenia (4932 patients), 16 in bipolar disorder (975 patients) and 10 in first-degree relatives (848 subjects) met the inclusion criteria. P50 sensory gating ratio (S2/S1) and S1-S2 difference were significantly altered in schizophrenia, bipolar disorder and their first-degree relatives. First-episode psychosis did not differ from schizophrenia, however episodes altered P50 sensory gating in bipolar disorder. Medications improve P50 sensory gating alterations in schizophrenia significantly and at trend level in bipolar disorder. Future studies should examine longitudinal course of P50 sensory gating in schizophrenia and bipolar disorder.

P50, N100, and P200 Auditory Sensory Gating Deficits in Schizophrenia Patients

BACKGROUND

Sensory gating describes neurological processes of filtering out redundant or unnecessary stimuli during information processing, and sensory gating deficits may contribute to the symptoms of schizophrenia. Among the three components of auditory event-related potentials reflecting sensory gating, P50 implies pre-attentional filtering of sensory information and N100/P200 reflects attention triggering and allocation processes. Although diminished P50 gating has been extensively documented in patients with schizophrenia, previous studies on N100 were inconclusive, and P200 has been rarely examined. This study aimed to investigate whether patients with schizophrenia have P50, N100, and P200 gating deficits compared with control subjects.

METHODS

Control subjects and clinically stable schizophrenia patients were recruited. The mid-latency auditory evoked responses, comprising P50, N100, and P200, were measured using the auditory-paired click paradigm without manipulation of attention. Sensory gating parameters included S1 amplitude, S2 amplitude, amplitude difference (S1-S2), and gating ratio (S2/S1). We also evaluated schizophrenia patients with PANSS to be correlated with sensory gating indices.

RESULTS

One hundred four patients and 102 control subjects were examined. Compared to the control group, schizophrenia patients had significant sensory gating deficits in P50, N100, and P200, reflected by larger gating ratios and smaller amplitude differences. Further analysis revealed that the S2 amplitude of P50 was larger, while the S1 amplitude of N100/P200 was smaller, in schizophrenia patients than in the controls. We found no correlations between sensory gating indices and schizophrenia positive or negative symptom clusters. However, we found a negative correlation between the P200 S2 amplitude and Bell's emotional discomfort factor/Wallwork's depressed factor.

CONCLUSION

Till date, this study has the largest sample size to analyze P50, N100, and P200 collectively by adopting the passive auditory paired-click paradigm without distractors. With covariates controlled for possible confounds, such as age, education, smoking amount and retained pairs, we found that schizophrenia patients had significant sensory gating deficits in P50-N100-P200. The schizophrenia patients had demonstrated a unique pattern of sensory gating deficits, including repetition suppression deficits in P50 and stimulus registration deficits in N100/200. These results suggest that sensory gating is a pervasive cognitive abnormality in schizophrenia patients that is not limited to the pre-attentive phase of information processing. Since P200 exhibited a large effect size and did not require additional time during recruitment, future studies of P50-N100-P200 collectively are highly recommended.

P50-N100-P200 sensory gating deficits in adolescents and young adults with autism spectrum disorders

Sensory symptoms are common in individuals with autism spectrum disorder (ASD). Altered sensory gating may cause sensory overload. However, whether ASD individuals have P50 gating deficits is controversial in childhood and lacks evidence in adulthood. Beyond P50, fewer studies have examined N100 or P200, although N100 is considered to be more reliable than P50. Also, the clinical correlates of these parameters are mostly unknown. This study aimed to investigate P50, N100, and P200 sensory gating in adolescents and young adults with ASD and examine their clinical correlates. In a sample of 34 ASD participants (mean age 20.6 ± 4.1, female 5.9%) and 34 sex- and age-matched typically-developing controls (TDC, mean age 20.4 ± 3.1), we investigated P50, N100, and P200 sensory gating by a paired-click paradigm, which generated the data of S1 amplitude after the first click and S2 amplitude after the second click. We found that compared to TDC, ASD participants had significant N100 suppression deficits reflected by a larger N100 S2 amplitude, smaller N100 ratio of S2 over S1, and the difference between the two amplitudes. N100 S2 amplitude was significantly associated with sensory sensitivity independent of the diagnosis. Although there was no group difference in P50 suppression, S1 amplitude was negatively associated with social deficits in ASD. P200 gating parameters were correlated with attention switching difficulty. Our findings suggest N100 gating deficit in adolescents and young adults with ASD. The relationships between P50 S1 and social deficits and between N100 S2 and sensory sensitivity warrant further investigation.

Sex as a Moderating Factor in the Relationship Between Hippocampal Volume and Sensory Gating in Patients With Schizophrenia

Building on the knowledge of sex differences in auditory sensory gating in schizophrenia and hippocampal involvement in sensory gating, this study aimed to investigate sex as a potential moderator of the association between hippocampal volume and P50 in schizophrenia. Auditory P50 gating and hippocampal volume were measured in 16 male and 15 female patients with schizophrenia. The correlations between hippocampal volume and P50 were analyzed in males and females separately, corrected for potential confounders, including age, duration of illness, and antipsychotic medication. Different associative patterns of hippocampal volume with P50 gating ratio and with P50 difference were found by sex. The results suggest sex may play a role in the physiology of sensory gating.

Auditory Event-Related Potentials in Antipsychotic-Free Subjects With Ultra-High-Risk State and First-Episode Psychosis

Background: Auditory event-related potentials (ERPs) have been utilized to study defective information processing of patients with schizophrenia. To delineate the pathophysiological processes from pre-psychotic state to first-episode psychosis, a study on subjects from ultra-high-risk (UHR) state to first-episode psychosis, ideally in an antipsychotic-free condition, can add important information to our understanding. Methods: Patients with UHR state or at their first-episode psychosis (FEP) who were drug-naive or only have been temporarily treated with antipsychotics were assessed by auditory ERPs measurement, including P50/N100 (sensory gating) and duration mismatch negativity (MMN; deviance detection). A group of age-matched healthy subjects served as their controls. Results: A total of 42 patients (23 UHR and 19 FEP) and 120 control subjects were recruited, including 21 pure drug-naive and 21 with very short exposure to antipsychotics. Collapsing FEP and UHR as a patient group, they exhibited significant sensory deficits manifested as larger P50 S2 amplitude, larger N100 ratio, and smaller N100 difference, and significantly less deviance detection response revealed by MMN. Such differences were less significant when treating FEP and UHR separately for comparisons. Comparisons of ERP results between drug-naive subjects and antipsychotic-short-exposure subjects revealed no significant difference in any P50/N100 and MMN parameter. Conclusion: Our study is one of the few studies focused on drug-naive or minimally treated patients at pre- or early-psychotic states. Our results exhibited impaired performance in sensory gating and deviance detection shown by certain parameters. A longitudinal study with larger sample sizes will be helpful to provide more evidence to elucidate the role of antipsychotics on an individual's neurophysiological performance at different stages of psychosis.

Comparison of Auditory Middle-Latency Responses From Two Deconvolution Methods at 40 Hz

GOAL

Auditory middle-latency responses (MLRs) are reported to be particularly susceptible to stimulation rate. Deconvolution methods are necessary to unwrap the overlapping responses at a high rate under the linear superposition assumption. This study aims to investigate and compare the MLR characteristics at high and conventional stimulation rates.

METHODS

The characteristics were examined in healthy adults by using two closely related deconvolution paradigms, namely continuous-loop averaging deconvolution and multirate steady-state averaging deconvolution at a mean rate of 40 Hz, and a conventional low rate of 5 Hz.

RESULTS

The morphology and stability of the MLRs can benefit from a high-rate stimulation. It appears that stimulation sequencing strategies of deconvolution methods exerted divergent rate effects on MLR characteristics, which might be associated with different adaptation mechanisms.

CONCLUSION

MLRs obtained by two deconvolution methods and the conventional reference feature differently from one another.

SIGNIFICANCE

These findings have critical implications in our current understanding of the rate effects on MLR characteristics which may inspire further studies to explore the characteristics of evoked responses at high rates and deconvolution paradigms.

Different P50 sensory gating measures reflect different cognitive dysfunctions in schizophrenia

The P50 is an early component of auditory evoked potentials and a measure of sensory gating deficits. This evoked potential component is thought to be an important endophenotype candidate for schizophrenia. Recent research suggests that instead of the P50 ratio, S1 and S2 amplitudes should be evaluated for sensory gating. However, no studies have focused on the relationship between cognitive dysfunction and P50 sensory gating deficits using S1 and S2 amplitudes. The purpose of the present study was to investigate the association between the P50 ratio (S2/S1), S1 and S2 amplitudes, and neuropsychological cognitive domains using stepwise multiple linear regression analyses. Results demonstrated a significant relationship between executive functioning and the P50 ratio and between sustained attention and S2 amplitude, respectively. Our findings suggest that the P50 ratio and S2 amplitude reflect distinct neurophysiological substrates associated with different cognitive functions.

Physical Exercise Alleviates Health Defects, Symptoms, and Biomarkers in Schizophrenia Spectrum Disorder

Schizophrenia spectrum disorders are characterized by symptom profiles consisting of positive and negative symptoms, cognitive impairment, and a plethora of genetic, epigenetic, and phenotypic biomarkers. Assorted animal models of these disorders and clinical neurodevelopmental indicators have implicated neurodegeneration as an element in the underlying pathophysiology. Physical exercise or activity regimes--whether aerobic, resistance, or endurance--ameliorate regional brain and functional deficits not only in affected individuals but also in animal models of the disorder. Cognitive deficits, often linked to regional deficits, were alleviated by exercise, as were quality-of-life, independent of disorder staging and risk level. Apoptotic processes intricate to the etiopathogenesis of schizophrenia were likewise attenuated by physical exercise. There is also evidence of manifest benefits endowed by physical exercise in preserving telomere length and integrity. Not least, exercise improves overall health and quality-of-life. The notion of scaffolding as the outcome of physical exercise implies the "buttressing" of regional network circuits, neurocognitive domains, anti-inflammatory defenses, maintenance of telomeric integrity, and neuro-reparative and regenerative processes.