Inter-rater reliability of the neurological examination in schizophrenia

Potential Role of Smartphone Technology in Advancing Work on Neurological Soft Signs with a Focus on Schizophrenia

LEARNING OBJECTIVE AFTER PARTICIPATING IN THIS CME ACTIVITY, THE PSYCHIATRIST SHOULD BE BETTER ABLE TO

• Outline and Identify potential benefits of using neurological soft signs (NSS) as biomarkers of schizophrenia.

ABSTRACT

Since the late 1960s, NSS have been a focus of study across psychiatric illnesses, including depression, bipolar disorder, and schizophrenia in particular. Utilizing these subtle neurological impairments as biomarkers of illness has numerous benefits; NSS offer a direct connection between clinical presentation and neurological functioning, and assessments are cost-effective. However, incongruent measurement scales, confounding variables, and rating system subjectivity have hindered the advancement and scalability of NSS research and clinical implementation. This article provides a brief overview of the literature on NSS as related to schizophrenia, and proposes utilizing smartphone sensing technology to create standardized NSS assessments with objective scoring. Incorporating digital phenotyping into NSS assessment offers the potential to make measurement more scalable, accessible, and directly comparable across locations, cultures, and demographics. We conducted a narrative search in PubMed and APA PsycInfo using the following keywords: neurological soft signs, schizophrenia spectrum disorders, and psychotic illnesses. No date limitations were used. There is no other direct work on NSS and new smartphone methods like digital phenotyping; though, there is related work in neurology. Harnessing advances in smartphone technology could provide greater insight into and further our understanding of specific aspects of the NSS field. For instance, it could help us distinguish trait vs. state markers and better understand how distinct groups of signs may reflect different aspects of psychiatric illness and neurological impairment. In addition, such technology can help advance research on the capabilities of NSS as an effective diagnostic tool.

Trajectory of neurological examination abnormalities in antipsychotic-naïve first-episode psychosis population: a 1 year follow-up study

BACKGROUND

Neurological Examination Abnormalities (NES) are quantified by measuring subtle, partially localizable (cerebello-thalamo-prefrontal cortical circuit) and heritable neurological signs comprising sensory integration, motor coordination and complex motor sequencing that are associated with first-episode psychosis (FEP). A few studies have evaluated NES longitudinally and as a predictor for diagnostic and response classification, but these studies have been confounded, underpowered and divergent. We examined (1) baseline and longitudinal NES differences between diagnostic and year 1 response groups; (2) if NES predicts diagnostic and response groups and (3) relationships between clinical variables and NES measures in antipsychotic-naïve FEP.

METHODS

NES and clinical measures were obtained for FEP-schizophrenia (FEP-SZ, n = 232), FEP non-schizophrenia (FEP-NSZ, n = 117) and healthy controls (HC, n = 204). Response groups with >25% improvement in average year 1 positive and negative symptomatology scores were classified as responsive (n = 97) and <25% improvement as non-responsive (n = 95). Analysis of covariance, NES trajectory analysis and logistic regression models assessed diagnostic and response group differences. Baseline and longitudinal NES relationships with clinical variables were performed with Spearman correlations. Data were adjusted for age, sex, race, socioeconomic status and handedness.

RESULTS

Cognitive perceptual (COGPER) score was better than repetitive motor (REPMOT) at differentiating FEP-SZ from FEP-NSZ and distinguishing responders from non-responders. We identified significant group-specific associations between COGPER and worse GAF, positive and negative symptomatology and some of these findings persisted at 1-year assessment.

CONCLUSION

NES are an easy to administer, bedside-elicited, endophenotypic measure and could be a cost-effective clinical tool in antipsychotic-naïve FEP.

Neurological soft signs and cognitive functions: Amongst euthymic bipolar I disorder cases, non-affected first degree relatives and healthy controls

Both neurological soft signs (NSS) and cognitive deficits are present among euthymic bipolar patients. NSS could be related to neurocognitive performance, but this is not explored thoroughly. Healthy relatives of patients may also suffer from similar deficits. This study compared NSS and cognitive functions in euthymic Bipolar I Disorder (BPI) cases to their non-affected first degree relatives and healthy controls. We also investigated the association between NSS and cognitive functions in these three groups. NSS were assessed in three groups using Neurological Evaluation Scale-revised (NES-r). Eight cognitive domains were assessed in 31 euthymic BPI cases, their 30 non-affected first degree relatives and 30 healthy controls using Computerized Neurocognitive Battery (CNB). Euthymic BPI patients had significantly more NSS than non-affected first degree relatives on 5/7 tests (p-value ranges from 0.042 to p=0.0001) and healthy controls on all tests (p-value from 0.042 to <0.0001). Non-affected first degree relatives and controls did not have any significant difference. BPI participants performed worse than their non-affected first degree relatives on one neurocognitive domain of CNB (spatial memory accuracy, p=0.03) and healthy controls on four domains (spatial memory accuracy (p=0.04), abstraction and mental flexibility efficiency (p=0.04), spatial memory efficiency (p=0.04), and emotion efficiency (p=0.04). Non-affected relatives and healthy controls were similar on neurocognitive domains. Accuracy and efficiency indices of some specific cognitive domains were negatively associated with AV rating and tap copying NSS ratings.

Are neurological soft signs pre-existing markers in individuals with an at-risk mental state for psychosis?

Neurological soft signs (NSS) are more common in schizophrenic psychoses and in genetically high-risk individuals than in healthy controls. But nothing is known so far regarding individuals with a clinical at-risk mental state (ARMS). The goals of our study therefore were (a) to compare the NSS frequency in ARMS individuals to that of first-episode psychosis (FEP) patients and (b) to test whether NSS could predict the transition to psychosis. Neurological soft signs were assessed using a shortened version of the Neurological Evaluation Scale (NES). Fifty-three ARMS individuals (16 with later transition to psychosis=ARMS-T, and 37 without transition=ARMS-NT) and 27 FEP patients were recruited through the Basel Early Detection Clinic FePsy. Of the FEP patients 37% showed NSS. We found no significant differences between FEP and ARMS-T patients or between ARMS-NT and ARMS-T. Our findings of NSS being present already before transition to psychosis to the same extent as after transition provide further support to the neurodevelopmental hypothesis of schizophrenic psychoses. Furthermore, our findings might indicate that ARMS-NT individuals also suffer from some sort of neurodevelopmental abnormalities.

A step toward an objective quantification of subtle neurological signs in schizophrenia

Numerous reports have emphasized the value of neurological soft signs (NSS) as endophenotypic markers in schizophrenia. NSS also appear as useful prognostic predictors for functional outcome, response and tolerance to antipsychotics. Although several standardized scales have been proposed and offer fair inter-rater reliability, they still rely on the experience and accuracy of the investigators. This study was designed to assess NSS objectively. We evaluated 27 patients who met the Diagnostic and Statistical Manual, fourth edition (DSM-IV) criteria for schizophrenia and 15 healthy controls using a standardized examination encompassing a 23-item NSS scale as well as an assessment of parkinsonism and dyskinesia. Movements were then recorded using inertia sensors while the patients were performing a selection of motor items from the aforementioned scale (balance tasks, rapid alternative movements, rigidity). To our knowledge, this study is the first to provide an objective assessment of specific NSS in schizophrenia using inertial sensors. The results objectively demonstrate impairments in patients with schizophrenia when balance relies on proprioceptive information, with specific differences in groups of patients based on their NSS scores. Inertia sensors are promising, inexpensive and 'easy-to-use' tools that could improve the assessment of motor and sensory impairments in patients with schizophrenia in daily clinical practice, especially when the dysfunction is subtle.

Neurological soft signs in psychometrically identified schizotypy

Patients with schizophrenia often exhibit structural brain abnormalities, as well as neurological soft signs (NSS), consistent with its conceptualization as a neurodevelopmental disorder. NSS are mild, presumably nonlocalizing, neurological impairments that are inferred from performance deficits in domains such as sensory integration, motor coordination, and motor sequencing. The vulnerability for schizophrenia is presumed to be expressed across a broad continuum of impairment referred to as schizotypy. It is hypothesized that nondisordered people along the schizotypy continuum should exhibit elevated rates of NSS. The present study examined the relation of psychometrically identified positive and negative schizotypy with NSS using the Neurological Evaluation Scale in a nonclinically ascertained sample of young adults (n=177). As hypothesized, negative, but not positive, schizotypy was related to increased NSS in tasks that assessed fine and gross motor coordination, motor sequencing, eye movement abnormalities, and memory recall. However, positive schizotypy was associated with increased NSS in tasks related to sensory integration dysfunction. In general, the positivexnegative schizotypy interaction term was unrelated to individual NSS tasks. The findings support: a) the theory that the vulnerability for schizophrenia is expressed across a broad continuum of subclinical and clinical impairment referred to as schizotypy; b) the multidimensional structure of schizotypy; and c) the notion that schizotypy is an appropriate construct for understanding the etiology and development of schizophrenia-spectrum disorders.

Neurological abnormalities among offspring of persons with schizophrenia: relation to premorbid psychopathology

BACKGROUND

Neurological Examination Abnormalities (NEA, often called "neurological soft signs") have been observed in early schizophrenia and may be heritable. We investigated the prevalence, and neurocognitive and psychopathological correlates of NEA among offspring of schizophrenia patients who are at increased genetic risk for this illness.

METHODS

Neurological examinations were conducted on high risk (HR, n=74) and healthy comparison subjects (HS, n=86), using the Heinrichs-Buchanan scale. Cognitive-perceptual (CogPer) and repetitive motor (RepMot) subscores, and total NEA scores were computed. All HR and HS were assessed using K-SADS/SCID for diagnoses. Schizotypy was measured using the Magical Ideation and the Perceptual Aberration subscales (Chapman scale), attention using Continuous Performance Test (CPT-IP) and executive functions using the Wisconsin Card Sorting Test (WCST).

RESULTS

CogPer (F(1,160)=7.14, p=0.008) but not RepMot NEA scores were higher in HR subjects compared to HS after controlling for age and sex. CogPer NEA scores were higher in HR subjects with axis I psychopathology compared to those without (F(2,170)-6.41, p=0.002). HR subjects had higher schizotypy scores (composite of the magical ideation and perceptual aberration scales) (F(1,141)=23.25, p=0.000004). Schizotypy scores were negatively correlated with sustained attention and executive functions. In addition, schizotypy was positively correlated with CogPer NEA scores.

CONCLUSIONS

Young relatives at increased genetic risk for schizophrenia show more frequent NEA. CogPer but not RepMot NEA scores were elevated, consistent with our prior observation of CogPer NEA being relatively specific for schizophrenia. The observed relationships between NEA, cognitive impairments, schizotypy and axis I disorders suggest that NEA may characterize a subgroup of HR offspring at an elevated risk for psychopathology.

Are neurologic examination abnormalities heritable? A preliminary study

BACKGROUND

Neurologic examination abnormalities (NEA) are more prevalent among patients with schizophrenia as well as their unaffected relatives when compared with healthy controls, suggesting that NEA may be endophenotypes for schizophrenia. We estimated the heritability of NEA in moderately sized pedigrees. We also evaluated correlations between NEA and cognitive performance in order to examine their construct validity.

METHODS

Members of eight extended families, each consisting of two first degree relatives with schizophrenia/schizoaffective disorders, as well as available first- to fifth-degree relatives were examined (n=96 participants). A modification of the Neurological Evaluation Scale (NES) was employed, augmented with localizing signs. Where feasible, we used untransformed data such as error counts and completion time, rather than ordinal measures. Heritability was estimated using the variance component method, implemented in SOLAR.

RESULTS

Statistically significant heritability (h2) estimates were obtained for several measures (p<0.05, h2+/-standard error: rapid alternating movements, right-sided completion time, 0.99+/-0.19; alternating fist-palm test, completion time, 0.77+/-0.19 s, errors, 0.70+/-0.32; fist-ring test, right-sided completion time, 0.53+/-0.23 s, left-sided completion time, 0.70+/-0.21 s; go-no go task, correct responses, 0.93+/-0.33; audio-visual integration, correct responses, 0.79+/-0.54). For most items, heritability analysis was hampered by insufficient data variability (infrequent errors). Correlational analyses show some degree of divergence among types of NEA, repetitive motor tasks being associated with most domains of cognitive functioning other than executive functioning, and cognitive-perceptual tasks being associated with memory and executive functioning.

CONCLUSIONS

Significant familial influences on certain aspects of neurologic performance were detected. These heritable measures were also correlated with heritable neurocognitive measures.

Factor structure of the Neurological Evaluation Scale in a predominantly African American sample of patients with schizophrenia, unaffected relatives, and non-psychiatric controls

OBJECTIVE

This study aimed to identify latent factors of the most widely used scale to measure neurological soft signs, the Neurological Evaluation Scale (NES), in a sample of schizophrenia patients, their relatives, and non-psychiatric controls.

METHOD

The NES was administered following the format and instructions of the original scale [Buchanan, R.W., Heinrichs, D.W., 1989. The Neurological Evaluation Scale (NES): a structured instrument for the assessment of neurological signs in schizophrenia. Psychiatry Res. 27, 335-350]. Three factor analyses were conducted using: (1) 23 items of the scale, (2) these 23 items in a sample restricted to African American participants, and (3) 12 items previously recommended based on adequate inter-rater reliability [Sanders, R.D., Forman, S.D., Pierri, J.N., Baker, R.W., Kelley, M.E., van Kammen, D.P., Keshavan, M.S., 1998. Inter-rater reliability of the neurological examination in schizophrenia. Schizophr. Res. 29, 287-292].

RESULTS

Exploratory factor analysis in the overall sample (n = 110) revealed three factors of interest: a "coordination/Romberg" factor (which included the fist-edge-palm test, finger-thumb opposition, rapid alternating movements, and the Romberg test), a "sensory integration" factor (which included synkinesis, extinction, stereognosis, and audio-visual integration), and an "eye movements/tandem walk/overflow movements" factor (which included convergence, gaze impersistence, tandem walk, and adventitious overflow). Minimal differences were apparent when comparing these results with those obtained from an analysis including only African American participants (n = 99). Restricting the analysis to only 12 items resulted in two factors (with poor discriminant validity and internal consistency), which showed few similarities with previously reported exploratory factor analysis results.

CONCLUSIONS

This study shows that results of empirically-derived factors of the NES vary substantially across study samples and research groups, though there appear to be at least two consistent latent variables, one related to the repetition of motor tasks and another tapping the processing of sensory stimuli. The factors demonstrated in the present study are more consistent with the original conceptually-derived subscales than prior factor analyses. Thus, until further research replicates consistent subscales of subtle neurological impairment in a variety of settings and samples, the total NES score may be more useful when comparing results across studies. Further research on latent neurological factors is needed.

The effects of antipsychotic medication on factor and cluster structure of neurologic examination abnormalities in schizophrenia

This study extends a previous study of the factor structure of the neurologic examination in unmedicated schizophrenia, utilizing cluster analysis and adding a medicated condition. We administered a modified version of the Neurologic Evaluation Scale (NES) on two occasions to 80 patients with schizophrenia or schizoaffective disorder, once while on antipsychotic medications and once while off medication. Data were distilled by combining right- and left-side scores, and by excluding rarely abnormal and unreliable items from the analysis. Principal components analysis yielded an intuitive four-factor solution in the unmedicated condition, but an inscrutable five-factor solution during medication. Cluster analysis revealed three groups: normal, cognitively impaired, and diffusely impaired. These results were also less interpretable with data from the medicated condition. Neurologic performance was better in the medicated than in the unmedicated condition. As is the case with other domains of symptoms and performance in schizophrenia, relationships among neurologic exam variables are altered by the presence of antipsychotic medication.

Confirmatory factor analysis of the Neurological Evaluation Scale in unmedicated schizophrenia

Factor structure of the Neurological Evaluation Scale (NES) was evaluated in 95 unmedicated patients with schizophrenia using confirmatory factor analysis (CFA). CFA was used to test four competing models that were based on prior empirical work examining the factor structure of the NES, as well as on theoretical considerations. A three-factor solution composed of "repetitive motor," "cognitive-perceptual," and "balance-tandem" factors best accounted for the data. These findings are consistent with prior exploratory studies that have suggested the NES is a multidimensional procedure that assesses diverse neurological domains. The current results contribute to the development of empirical subscales for neurological assessment procedures to be used in psychiatric conditions.

Dyskinesia and soft neurological signs in schizophrenia: a comparative study

Objective. Several neurological abnormalities can be found at a greater frequency in patients with schizophrenia, including neurological soft signs (NSS) and signs of the "pyramidal" and "extrapyramidal" systems. We aimed to explore the frequency of movement disorders in patients with antipsychotic naïve schizophrenia and to compare and contrast with antipsychotic-treated patients and healthy controls. Methods. Twenty-two antipsychotic naive schizophrenic patients, 22 antipsychotic treated patients and 22 healthy control subjects were assessed by Neurological Evaluation (NES), Abnormal Involuntary Movements (AIMS), and Positive and Negative Syndrome (PANSS) Scales. Results. The NES scores of the never-medicated schizophrenic group were significantly higher than those of normal controls but did not differ significantly from the medicated group. Dyskinesia rates in the both schizophrenic groups were higher than in healthy controls. Medicated and non-medicated schizophrenic patient scores did not differ in AIMS with regard to facial and oral movements, but medicated patients scored higher than non-medicated subjects with respect to extremity movements. Conclusion. Our data suggest that: soft neurological signs and abnormal involuntary movements in the facial region are more prevalent in patients with schizophrenia, whether they are medicated or antipsychotic naïve. On the contrary, abnormal involuntary movements in the trunk and the extremities seem to be associated with medication.

Validation and factorial structure of a standardized neurological examination assessing neurological soft signs in schizophrenia

Although neurological soft signs (NSS) have been consistently reported in patients with schizophrenia, their clinical relevance, the actual impact of treatment or their evolution during the disease are not well clarified, possibly because of methodological limitations of the available tools. We have developed a new standardized examination integrating the assessment of 23 NSS selected from the literature and the rating of well-validated scales for assessment of extra-pyramidal symptoms. We examined 161 subjects (controls, n=48; patients with schizophrenia, n=95; or recurrent mood disorder, n=18). Half of the patients were neuroleptic-free. Schizophrenic patients had significantly higher total score (14. 6+/-8) than mood disorder patients (12.0+/-7) and controls (5.0+/-2). Internal consistency (Cronbach's alpha=0.85) and inter-rater reliability were good. Principal component analysis found five consistent factors ('motor coordination', 'motor integrative function', 'sensory integration', 'involuntary movements or posture', 'quality of lateralization'). This scale thus confirmed a factorial structure in agreement with the conceptual areas of interest explored by NSS and should be a useful tool for assessment of the different dimensions of neurological dysfunction in schizophrenia.

Factor structure of neurologic examination abnormalities in unmedicated schizophrenia

The heterogeneity and uncertain significance of neurologic exam abnormalities in schizophrenia prompted us to evaluate their factor structure. We administered a modified version of the Neurological Evaluation Scale (NES) to 103 unmedicated patients with schizophrenia. Data were distilled by combining right- and left-side scores, and by eliminating superfluous, rarely abnormal and unreliable items from the analysis. Exploratory principal components analysis yielded four factors: repetitive motor tasks (fist-ring, fist-edge-palm, alternating fist-palm, dysdiadochokinesis); cognitive-perceptual tasks (memory, audiovisual integration, right-left orientation, face-hand test, rhythm tapping reproduction); balancing tasks (Romberg, tandem gait); and the palmomental reflex. Evaluation of the relationship between these factors and clinical and demographic variables revealed a robust correlation between the cognitive-perceptual factor and full-scale IQ score. This analysis is a step toward developing empirical subscales of a modified NES, which may provide insights into the nature of neurologic impairment in schizophrenia and may prove clinically useful.