| 1 | Neuropsychologia 2000 -1 38: 1565-75 |
|---|---|
| PMID | 11074079 |
| Title | Paired-associate learning and memory interference in schizophrenia. |
| Abstract | Patients with frontal lobe damage have been shown to exhibit disproportionate impairments of second list learning as a result of interference effects. Based upon the assumption that schizophrenia is associated with frontal dysfunction, we attempted to explore how various manipulations of paired-associate learning tasks would interfere with schizophrenic patients' memory performance. Patients with schizophrenia were administered four tests of paired-associate learning, in which cue and response words were manipulated to increase interference across two study lists. In two tests of paired-associate learning (AB-AC test), cue words used in one list were repeated in a second list but were associated with different response words (e.g. lion-hunter, lion-circus). One version of this test employed moderately related word pairs and the other version employed unrelated word pairs. In the other two tests (AB-ABR test), all words used in one list were repeated in a second list but were rearranged to form new pairs. Again, one version of this test used moderately related word pairs and the other version used unrelated word pairs. We hypothesized that patients with schizophrenia would exhibit disproportionate impairment of second-list learning as a result of interference effects and that they would do especially poorly in the AB-ABR task, where the word pairs were unrelated. However, these predictions were not supported. Furthermore, it was difficult to tease apart a specific problem in list discrimination from the generally poor memory of the schizophrenic patients. We suggest that the susceptibility to these interference effects in patients with schizophrenia is not a specific problem in cognition, but rather one that is confounded by general memory problems. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 2 | Neuropsychologia 2000 -1 38: 1565-75 |
| PMID | 11074079 |
| Title | Paired-associate learning and memory interference in schizophrenia. |
| Abstract | Patients with frontal lobe damage have been shown to exhibit disproportionate impairments of second list learning as a result of interference effects. Based upon the assumption that schizophrenia is associated with frontal dysfunction, we attempted to explore how various manipulations of paired-associate learning tasks would interfere with schizophrenic patients' memory performance. Patients with schizophrenia were administered four tests of paired-associate learning, in which cue and response words were manipulated to increase interference across two study lists. In two tests of paired-associate learning (AB-AC test), cue words used in one list were repeated in a second list but were associated with different response words (e.g. lion-hunter, lion-circus). One version of this test employed moderately related word pairs and the other version employed unrelated word pairs. In the other two tests (AB-ABR test), all words used in one list were repeated in a second list but were rearranged to form new pairs. Again, one version of this test used moderately related word pairs and the other version used unrelated word pairs. We hypothesized that patients with schizophrenia would exhibit disproportionate impairment of second-list learning as a result of interference effects and that they would do especially poorly in the AB-ABR task, where the word pairs were unrelated. However, these predictions were not supported. Furthermore, it was difficult to tease apart a specific problem in list discrimination from the generally poor memory of the schizophrenic patients. We suggest that the susceptibility to these interference effects in patients with schizophrenia is not a specific problem in cognition, but rather one that is confounded by general memory problems. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 3 | J Laryngol Otol 2005 May 119: 352-5 |
| PMID | 15949097 |
| Title | Is it necessary to differentiate tinnitus from auditory hallucination in schizophrenic patients? |
| Abstract | Although the definitions of subjective tinnitus and auditory hallucination are very similar, the origins and underlying causes of each symptom clearly differ. This study examined whether the differentiation of tinnitus from auditory hallucination is necessary for the proper management of these symptoms in schizophrenic patients. We investigated the characteristics of auditory hallucinations in 15 schizophrenic patients, and measured their pure-tone hearing levels and auditory brainstem responses (ABR). The average hearing level was 20.6 +/- 16.2 dB, with a mild decrease at high frequencies. We classified the patients into three groups: pure hallucination, tinnitus, and hallucination plus tinnitus. Eight patients (53.3 per cent) complained of pure hallucination and only one of them had a mild hearing loss. Hearing deficits were observed in six of seven tinnitus patients. Abnormal findings of ABR were found only in the pure hallucination group. The results suggest that tinnitus should be differentiated from auditory hallucination in the evaluation of schizophrenic patients. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 4 | Neuropsychiatr Dis Treat 2010 -1 6: 289-96 |
| PMID | 20628629 |
| Title | Abnormal auditory forward masking pattern in the brainstem response of individuals with Asperger syndrome. |
| Abstract | Abnormal auditory information processing has been reported in individuals with autism spectrum disorders (ASD). In the present study auditory processing was investigated by recording auditory brainstem responses (ABRs) elicited by forward masking in adults diagnosed with Asperger syndrome (AS). Sixteen AS subjects were included in the forward masking experiment and compared to three control groups consisting of healthy individuals (n = 16), schizophrenic patients (n = 16) and attention deficit hyperactivity disorder patients (n = 16), respectively, of matching age and gender. The results showed that the AS subjects exhibited abnormally low activity in the early part of their ABRs that distinctly separated them from the three control groups. Specifically, wave III amplitudes were significantly lower in the AS group than for all the control groups in the forward masking condition (P < 0.005), which was not the case in the baseline condition. Thus, electrophysiological measurements of ABRs to complex sound stimuli (eg, forward masking) may lead to a better understanding of the underlying neurophysiology of AS. Future studies may further point to specific ABR characteristics in AS individuals that separate them from individuals diagnosed with other neurodevelopmental diseases. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 5 | Psychiatry Res 2012 Apr 196: 188-93 |
| PMID | 22326876 |
| Title | Lateral asymmetry and reduced forward masking effect in early brainstem auditory evoked responses in schizophrenia. |
| Abstract | Individuals diagnosed with schizophrenia show deficiencies of basic neurophysiological sorting mechanisms. This study further investigated this issue, focusing on the two phenomena, laterality of coding and auditory forward masking. A specific audiometric method for use in psychiatry was the measuring set up to register brain stem audiograms (ABRs). A sample of 49 schizophrenic patients was compared with three control groups consisting of healthy reference subjects (n=49), attention deficit hyperactivity disorder (ADHD) patients (n=29), Asperger syndrome (AS) patients (n=13) and drug-induced psychotic patients (n=14). schizophrenic patients showed significant abnormal laterality of brainstem activity in wave II of the auditory brainstem response (ABR) in comparison with all other study groups. Forward masking effects in the superior olive complex were coded significantly differently by schizophrenic patients compared to control groups except for the AS group. The results suggest deficits in the coding of auditory stimuli in the lower parts of the auditory pathway in schizophrenia and indicate that increased peripheral lateral asymmetry and forward masking aberrances could be neurophysiological markers for the disorder. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 6 | Psychiatry Res 2012 Apr 196: 188-93 |
| PMID | 22326876 |
| Title | Lateral asymmetry and reduced forward masking effect in early brainstem auditory evoked responses in schizophrenia. |
| Abstract | Individuals diagnosed with schizophrenia show deficiencies of basic neurophysiological sorting mechanisms. This study further investigated this issue, focusing on the two phenomena, laterality of coding and auditory forward masking. A specific audiometric method for use in psychiatry was the measuring set up to register brain stem audiograms (ABRs). A sample of 49 schizophrenic patients was compared with three control groups consisting of healthy reference subjects (n=49), attention deficit hyperactivity disorder (ADHD) patients (n=29), Asperger syndrome (AS) patients (n=13) and drug-induced psychotic patients (n=14). schizophrenic patients showed significant abnormal laterality of brainstem activity in wave II of the auditory brainstem response (ABR) in comparison with all other study groups. Forward masking effects in the superior olive complex were coded significantly differently by schizophrenic patients compared to control groups except for the AS group. The results suggest deficits in the coding of auditory stimuli in the lower parts of the auditory pathway in schizophrenia and indicate that increased peripheral lateral asymmetry and forward masking aberrances could be neurophysiological markers for the disorder. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 7 | PLoS ONE 2013 -1 8: e80104 |
| PMID | 24244619 |
| Title | Hearing loss in a mouse model of 22q11.2 Deletion Syndrome. |
| Abstract | 22q11.2 Deletion Syndrome (22q11DS) arises from an interstitial chromosomal microdeletion encompassing at least 30 genes. This disorder is one of the most significant known cytogenetic risk factors for schizophrenia, and can also cause heart abnormalities, cognitive deficits, hearing difficulties, and a variety of other medical problems. The Df1/+ hemizygous knockout mouse, a model for human 22q11DS, recapitulates many of the deficits observed in the human syndrome including heart defects, impaired memory, and abnormal auditory sensorimotor gating. Here we show that Df1/+ mice, like human 22q11DS patients, have substantial rates of hearing loss arising from chronic middle ear infection. Auditory brainstem response (ABR) measurements revealed significant elevation of click-response thresholds in 48% of Df1/+ mice, often in only one ear. Anatomical and histological analysis of the middle ear demonstrated no gross structural abnormalities, but frequent signs of otitis media (OM, chronic inflammation of the middle ear), including excessive effusion and thickened mucosa. In mice for which both in vivo ABR thresholds and post mortem middle-ear histology were obtained, the severity of signs of OM correlated directly with the level of hearing impairment. These results suggest that abnormal auditory sensorimotor gating previously reported in mouse models of 22q11DS could arise from abnormalities in auditory processing. Furthermore, the findings indicate that Df1/+ mice are an excellent model for increased risk of OM in human 22q11DS patients. Given the frequently monaural nature of OM in Df1/+ mice, these animals could also be a powerful tool for investigating the interplay between genetic and environmental causes of OM. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 8 | Front Psychiatry 2014 -1 5: 142 |
| PMID | 25352811 |
| Title | The auditory brain-stem response to complex sounds: a potential biomarker for guiding treatment of psychosis. |
| Abstract | Cognitive deficits limit psychosocial functioning in schizophrenia. For many patients, cognitive remediation approaches have yielded encouraging results. Nevertheless, therapeutic response is variable, and outcome studies consistently identify individuals who respond minimally to these interventions. Biomarkers that can assist in identifying patients likely to benefit from particular forms of cognitive remediation are needed. Here, we describe an event-related potential (ERP) biomarker - the auditory brain-stem response (ABR) to complex sounds (cABR) - that appears to be particularly well-suited for predicting response to at least one form of cognitive remediation that targets auditory information processing. Uniquely, the cABR quantifies the fidelity of sound encoded at the level of the brainstem and midbrain. This ERP biomarker has revealed auditory processing abnormalities in various neurodevelopmental disorders, correlates with functioning across several cognitive domains, and appears to be responsive to targeted auditory training. We present preliminary cABR data from 18 schizophrenia patients and propose further investigation of this biomarker for predicting and tracking response to cognitive interventions. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 9 | Neuropsychiatr Dis Treat 2014 -1 10: 1011-6 |
| PMID | 24944514 |
| Title | A new method for analyzing auditory brain-stem response waveforms using a moving-minimum subtraction procedure of digitized analog recordings. |
| Abstract | The auditory brain-stem response (ABR) waveform comprises a set of waves (labeled I-VII) recorded with scalp electrodes over 10 ms after an auditory stimulation with a brief click sound. Quite often, the waves are fused (confluent) and baseline-irregular and sloped, making wave latencies and wave amplitudes difficult to establish. In the present paper, we describe a method, labeled moving-minimum subtraction, based on digitization of the analog ABR waveform (154 data points/ms) in order to achieve alignment of the ABR response to a straight baseline, often with clear baseline separation of waves and resolution of fused waves. Application of the new method to groups of patients showed marked differences in ABR waveforms between patients with schizophrenia versus patients with adult attention deficit/hyperactivity disorder versus healthy controls. The findings show promise regarding the possibility to identify ABR markers to be used as biomarkers as support for clinical diagnoses of these and other neuropsychiatric disorders. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 10 | J Affect Disord 2014 Dec 169: 105-11 |
| PMID | 25173433 |
| Title | Thalamocortical abnormalities in auditory brainstem response patterns distinguish DSM-IV bipolar disorder type I from schizophrenia. |
| Abstract | Bipolar disorder type I (BP-I) belongs to a spectrum of affective disorders that are expressed in many different ways and therefore can be difficult to distinguish from other conditions, especially unipolar depression, schizoaffective disorder, schizophrenia (SZ), but also anxiety and personality disorders. Since early diagnosis and treatment have shown to improve the long-term prognosis, complementary specific biomarkers are of great value. The auditory brainstem response (ABR) has previously been applied successfully to identify specific abnormal ABR patterns in SZ and Asperger syndrome. The current study investigated the early auditory processing of complex sound stimuli e.g. forward masking, in BP-I compared to SZ patients. The ABR curves of BP-I patients (n=23) and SZ patients (n=20) were analyzed in terms of peak amplitudes and correlation with an ABR norm curve based on a non-psychiatric control group (n=20). BP-I patients had significantly higher wave III (p=0.0062) and wave VII (p=0.0472) amplitudes compared with SZ patients. Furthermore, BP-I patients, and to a lesser extent SZ patients, showed low correlation with the norm ABR curve in the part of the curve comprising waves VI-VII. Sample size was relatively small and study groups were not matched for age and gender. BP-I patients showed specific aberrances, specifically in the latter part of the ABR curve, implicating abnormalities in thalamocortical circuitry. The abnormal ABR wave patterns significantly separated BP-I patients from SZ patients suggesting that ABR might serve as a biomarker for BP-I. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |