Neurocognitive dimensions characterising patients with first-episode psychosis

Background

Assessment of neurocognitive dysfunction in schizophrenia is hampered by the multitude of tests used in the literature.

Aims

We aimed to identify the main dimensions of an assessment battery for patients with first-episode psychosis and to estimate the relationship between dimension scores and gender, age, education, diagnosis and symptoms.

Method

Eight frequently used neuropsychological tests were used. We tested 219 patients 3 months after start of therapy or at remission, whichever occurred first.

Results

We identified five dimensions: working memory (WM); verbal learning (VL); executive function (EF); impulsivity (Im); and motor speed (MS). Significant findings were that the MS score was higher for men, and the WM and VL scores were correlated with years of education.

Conclusions

Neurocognitive function in first-episode psychosis is described by at least five independent dimensions.

GWAS meta-analysis reveals novel loci and genetic correlates for general cognitive function: a report from the COGENT consortium

This corrects the article DOI: 10.1038/mp.2016.244.

GWAS meta-analysis reveals novel loci and genetic correlates for general cognitive function: a report from the COGENT consortium

The complex nature of human cognition has resulted in cognitive genomics lagging behind many other fields in terms of gene discovery using genome-wide association study (GWAS) methods. In an attempt to overcome these barriers, the current study utilized GWAS meta-analysis to examine the association of common genetic variation (~8M single-nucleotide polymorphisms (SNP) with minor allele frequency ⩾1%) to general cognitive function in a sample of 35 298 healthy individuals of European ancestry across 24 cohorts in the Cognitive Genomics Consortium (COGENT). In addition, we utilized individual SNP lookups and polygenic score analyses to identify genetic overlap with other relevant neurobehavioral phenotypes. Our primary GWAS meta-analysis identified two novel SNP loci (top SNPs: rs76114856 in the CENPO gene on chromosome 2 and rs6669072 near LOC105378853 on chromosome 1) associated with cognitive performance at the genome-wide significance level (P<5 × 10^-8). Gene-based analysis identified an additional three Bonferroni-corrected significant loci at chromosomes 17q21.31, 17p13.1 and 1p13.3. Altogether, common variation across the genome resulted in a conservatively estimated SNP heritability of 21.5% (s.e.=0.01%) for general cognitive function. Integration with prior GWAS of cognitive performance and educational attainment yielded several additional significant loci. Finally, we found robust polygenic correlations between cognitive performance and educational attainment, several psychiatric disorders, birth length/weight and smoking behavior, as well as a novel genetic association to the personality trait of openness. These data provide new insight into the genetics of neurocognitive function with relevance to understanding the pathophysiology of neuropsychiatric illness.

Modelling difficulties in abstract thinking in psychosis: the importance of socio-developmental background

INTRODUCTION

Abstract thinking is important in modern understanding of neurocognitive abilities, and a symptom of thought disorder in psychosis. In patients with psychosis, we assessed if socio-developmental background influences abstract thinking, and the association with executive functioning and clinical psychosis symptoms.

METHODS

Participants (n = 174) had a diagnosis of psychotic or bipolar disorder, were 17-65 years, intelligence quotient (IQ) > 70, fluent in a Scandinavian language, and their full primary education in Norway. Immigrants (N = 58) were matched (1:2) with participants without a history of migration (N = 116). All participants completed a neurocognitive and clinical assessment. Socio-developmental background was operationalised as human developmental index (HDI) of country of birth, at year of birth. Structural equation modelling was used to assess the model with best fit.

RESULTS

The model with best fit, χ² = 96.591, df = 33, p < .001, confirmed a significant indirect effect of HDI scores on abstract thinking through executive functioning, but not through clinical psychosis symptoms.

CONCLUSIONS

This study found that socio-developmental background influences abstract thinking in psychosis by indirect effect through executive functioning. We should take into account socio-developmental background in the interpretation of neurocognitive performance in patients with psychosis, and prioritise cognitive remediation in treatment of immigrant patients.

Genome-wide autozygosity is associated with lower general cognitive ability

Inbreeding depression refers to lower fitness among offspring of genetic relatives. This reduced fitness is caused by the inheritance of two identical chromosomal segments (autozygosity) across the genome, which may expose the effects of (partially) recessive deleterious mutations. Even among outbred populations, autozygosity can occur to varying degrees due to cryptic relatedness between parents. Using dense genome-wide single-nucleotide polymorphism (SNP) data, we examined the degree to which autozygosity associated with measured cognitive ability in an unselected sample of 4854 participants of European ancestry. We used runs of homozygosity-multiple homozygous SNPs in a row-to estimate autozygous tracts across the genome. We found that increased levels of autozygosity predicted lower general cognitive ability, and estimate a drop of 0.6 s.d. among the offspring of first cousins (P=0.003-0.02 depending on the model). This effect came predominantly from long and rare autozygous tracts, which theory predicts as more likely to be deleterious than short and common tracts. Association mapping of autozygous tracts did not reveal any specific regions that were predictive beyond chance after correcting for multiple testing genome wide. The observed effect size is consistent with studies of cognitive decline among offspring of known consanguineous relationships. These findings suggest a role for multiple recessive or partially recessive alleles in general cognitive ability, and that alleles decreasing general cognitive ability have been selected against over evolutionary time.

Neuropsychological testing of cognitive impairment in euthymic bipolar disorder: an individual patient data meta-analysis

OBJECTIVE

An association between bipolar disorder and cognitive impairment has repeatedly been described, even for euthymic patients. Findings are inconsistent both across primary studies and previous meta-analyses. This study reanalysed 31 primary data sets as a single large sample (N = 2876) to provide a more definitive view.

METHOD

Individual patient and control data were obtained from original authors for 11 measures from four common neuropsychological tests: California or Rey Verbal Learning Task (VLT), Trail Making Test (TMT), Digit Span and/or Wisconsin Card Sorting Task.

RESULTS

Impairments were found for all 11 test-measures in the bipolar group after controlling for age, IQ and gender (Ps ≤ 0.001, E.S. = 0.26-0.63). Residual mood symptoms confound this result but cannot account for the effect sizes found. Impairments also seem unrelated to drug treatment. Some test-measures were weakly correlated with illness severity measures suggesting that some impairments may track illness progression.

CONCLUSION

This reanalysis supports VLT, Digit Span and TMT as robust measures of cognitive impairments in bipolar disorder patients. The heterogeneity of some test results explains previous differences in meta-analyses. Better controlling for confounds suggests deficits may be smaller than previously reported but should be tracked longitudinally across illness progression and treatment.

Schizophrenia patients with and without post-traumatic stress disorder (PTSD) have different mood symptom levels but same cognitive functioning

OBJECTIVE

To investigate differences in cognitive function and level of psychopathology in patients with schizophrenia (SZ) with or without psychological traumatization/post-traumatic stress disorder (PTSD). We hypothesized that traumatized patients with or without PTSD would have more severe cognitive impairments because of the neuropathological changes associated with PTSD, and more severe psychopathology compared with non-traumatized SZ patients.

METHOD

Seventy-five SZ patients with traumatization and 217 SZ patients without traumatization were evaluated regarding the symptoms and cognitive functioning, using standard symptom scales (PANSS; CDSS) and a neuropsychological test battery (IQ, verbal memory, attention, working memory, psychomotor speed, and executive functioning).

RESULTS

No significant differences were observed between the groups in cognitive test performance. The patients in the traumatized group with PTSD showed significantly more current depression than the non-traumatized group (P = 0.012).

CONCLUSION

The findings did not support the hypothesis that the presence of comorbid PTSD/traumatization in SZ is associated with increased cognitive impairment. The increase in current depression in SZ with comorbid traumatization suggests that more severe psychopathology is associated with traumatization.

Predictors of medication adherence in patients with schizophrenia and bipolar disorder

OBJECTIVE

To investigate potential risk factors for medication non-adherence in patients with schizophrenia and bipolar disorder.

METHOD

A total of 255 patients underwent clinical assessments, neurocognitive testing and blood sampling. The patients were divided into groups of 'No', 'Partial' or 'Full' adherence. Relationships to different risk factors were analyzed.

RESULTS

In schizophrenia, use of illicit substances, alcohol and poor insight were related to worse adherence. Schizophrenia patients with No adherence did better on tests of executive functioning, verbal learning and memory and had higher IQ than patients with better adherence. There were higher levels of autonomic side effects in the non-adherence group, but body mass index was lower in the Partial adherence group than in the Full adherence group. In the bipolar disorder patients, there was an association between the use of illicit substances and alcohol and poor adherence. We found no relationship between adherence behavior and neurocognition in the bipolar disorder group.

CONCLUSION

Substance use is an important risk factor for non-adherence in patients with schizophrenia and bipolar disorder. Poor insight is also a risk factor in schizophrenia. The results suggest that cognitive dysfunction is not a risk factor for non-adherence in these diagnostic groups.

Predictors of medication adherence in patients with schizophrenia and bipolar disorder

OBJECTIVE

To investigate potential risk factors for medication non-adherence in patients with schizophrenia and bipolar disorder.

METHOD

A total of 255 patients underwent clinical assessments, neurocognitive testing and blood sampling. The patients were divided into groups of 'No', 'Partial' or 'Full' adherence. Relationships to different risk factors were analyzed.

RESULTS

In schizophrenia, use of illicit substances, alcohol and poor insight were related to worse adherence. Schizophrenia patients with No adherence did better on tests of executive functioning, verbal learning and memory and had higher IQ than patients with better adherence. There were higher levels of autonomic side effects in the non-adherence group, but body mass index was lower in the Partial adherence group than in the Full adherence group. In the bipolar disorder patients, there was an association between the use of illicit substances and alcohol and poor adherence. We found no relationship between adherence behavior and neurocognition in the bipolar disorder group.

CONCLUSION

Substance use is an important risk factor for non-adherence in patients with schizophrenia and bipolar disorder. Poor insight is also a risk factor in schizophrenia. The results suggest that cognitive dysfunction is not a risk factor for non-adherence in these diagnostic groups.

TCF4 sequence variants and mRNA levels are associated with neurodevelopmental characteristics in psychotic disorders

TCF4 is involved in neurodevelopment, and intergenic and intronic variants in or close to the TCF4 gene have been associated with susceptibility to schizophrenia. However, the functional role of TCF4 at the level of gene expression and relationship to severity of core psychotic phenotypes are not known. TCF4 mRNA expression level in peripheral blood was determined in a large sample of patients with psychosis spectrum disorders (n = 596) and healthy controls (n = 385). The previously identified TCF4 risk variants (rs12966547 (G), rs9960767 (C), rs4309482 (A), rs2958182 (T) and rs17512836 (C)) were tested for association with characteristic psychosis phenotypes, including neurocognitive traits, psychotic symptoms and structural magnetic resonance imaging brain morphometric measures, using a linear regression model. Further, we explored the association of additional 59 single nucleotide polymorphisms (SNPs) covering the TCF4 gene to these phenotypes. The rs12966547 and rs4309482 risk variants were associated with poorer verbal fluency in the total sample. There were significant associations of other TCF4 SNPs with negative symptoms, verbal learning, executive functioning and age at onset in psychotic patients and brain abnormalities in total sample. The TCF4 mRNA expression level was significantly increased in psychosis patients compared with controls and positively correlated with positive- and negative-symptom levels. The increase in TCF4 mRNA expression level in psychosis patients and the association of TCF4 SNPs with core psychotic phenotypes across clinical, cognitive and brain morphological domains support that common TCF4 variants are involved in psychosis pathology, probably related to abnormal neurodevelopment.

Opposite relationships between cannabis use and neurocognitive functioning in bipolar disorder and schizophrenia

BACKGROUND

Cannabis use is associated with altered neurocognitive functioning in severe mental disorders, but data are still inconclusive and there are no studies of bipolar disorder. The aim of this study was to investigate the association between cannabis use and neurocognition in bipolar disorder compared with schizophrenia in a naturalistic setting.

METHOD

A total of 133 patients with bipolar disorder and 140 patients with schizophrenia underwent neuropsychological assessments and clinical characterization including measures of substance use. Relationships between cannabis users and neurocognitive function were explored in the two diagnostic groups. Possible interactions between diagnosis and cannabis use were investigated, and findings were controlled for possible confounders.

RESULTS

In bipolar disorder subjects, cannabis use was associated with better neurocognitive function, but the opposite was the case for the schizophrenia subjects. There was a statistically significant interaction effect of diagnosis and cannabis use on focused attention (p=0.019), executive functioning (verbal fluency--set shifting) (p=0.009), logical memory-learning (p=0.007) and on logical memory-recall (p=0.004). These differences in neurocognitive function could not be explained by putative confounders.

CONCLUSIONS

The findings suggest that cannabis use may be related to improved neurocognition in bipolar disorder and compromised neurocognition in schizophrenia. The results need to be replicated in independent samples, and may suggest different underlying disease mechanisms in the two disorders.

Self-Evaluation of Memory Functioning in Depressed Patients During a Symptomatic Episode and After Recovery

Objective:

Depressed patients tend to under-estimate their everyday memory function. Whether this under-estimation is related to the depressive state, or whether it represents underlying personality traits present also between or after depressive episodes, is not clear.

Methods:

Comparisons of subjective memory evaluation as measured by the Everyday Memory Questionnaire (EMQ) were made between sub-groups with Current Depression (N=14), Previous Depression (N=19), and Healthy Controls (N=10). Analyses were adjusted for effects of sociodemographic variables, use of medication, and premorbid intellectual abilities (Similarities sub-test (WASI)). To assess the relationship between affective state and subjective memory function irrespective of actual memory performance, adjustment for objective memory performance as represented by the Total recall sub-task from CVLT and Long-delayed free recall from RCFT was included in a final step in the ANCOVA model.

Results:

The overall crude relationship between group and EMQ total score was significant (F(2,40)=4.11, p=0.011, eta sq.= .17). In posthoc follow-up tests, the Currently Depressed reported significantly lower on EMQ than both Previously Depressed and Controls (Dunnett's C test, p= .018 and p= .034, respectively). However, after adjustment for relevant confounders and mediators, both the Previously and Currently Depressed performed significantly worse on EMQ compared to Controls (overall ANCOVA F(2,33)=9.22, p= .001, eta sq.= .36; pairwise follow-ups p= .001 and p= .011, respectively).

Conclusion:

Depressed patients’ under-estimation of their memory function is independent of mood state and it may represent a vulnerability or personality structure involving negative cognitive patterns that may be successfully targeted by cognitive therapy.

Illicit drug use in patients with psychotic disorders compared with that in the general population: a cross-sectional study

OBJECTIVE

Prevalence estimates of illicit drug use in psychotic disorders vary between studies, and only a few studies compared prevalence estimates with those in the general population.

METHOD

Cross-sectional study comparing 148 stable-phase patients with schizophrenia or bipolar disorder with 329 representative general citizens of Oslo. A total of 849 patients from the same hospital department in the same time period constituted a patient reference group.

RESULTS

Lifetime illicit drug use was 44% higher (P < 0.001) in study patients than in the general population sample; while lifetime use of amphetamine/cocaine was 160% higher (P < 0.001). No differences were found between user groups for sociodemographic characteristics.

CONCLUSION

Patients with psychotic disorders in stable phase had a markedly higher lifetime use of any illicit substance, especially amphetamine/cocaine, than the general population. They also seemed to use drugs more periodically. The same sociodemographic characteristics were associated with increased illicit drug use in both groups.

The effect of gender on emotion perception in schizophrenia and bipolar disorder

OBJECTIVE

Impaired emotion perception is documented for schizophrenia, but findings have been mixed for bipolar disorder. In healthy samples females perform better than males. This study compared emotion perception in schizophrenia and bipolar disorder and investigated the effects of gender.

METHOD

Visual (facial pictures) and auditory (sentences) emotional stimuli were presented for identification and discrimination in groups of participants with schizophrenia, bipolar disorder and healthy controls.

RESULTS

Visual emotion perception was unimpaired in both clinical groups, but the schizophrenia sample showed reduced auditory emotion perception. Healthy males and male schizophrenia subjects performed worse than their female counterparts, whereas there were no gender differences within the bipolar group.

CONCLUSION

A disease-specific auditory emotion processing deficit was confirmed in schizophrenia, especially for males. Participants with bipolar disorder performed unimpaired.

Neuropsychological test profiles in schizophrenia and non-psychotic depression

OBJECTIVE

The study examined to what degree schizophrenia is characterized by a neuropsychological (NP) test profile specific in shape and level compared with depression and normal functioning.

METHOD

Fifty-three patients with schizophrenia, 45 with non-psychotic depression, and 50 normals were assessed with a comprehensive NP test battery and clinical instruments. NP test scores were factor analyzed into seven composite scores.

RESULTS

Schizophrenia patients performed significantly below normals across all seven composite scores, whereas depression patients were impaired in two. Verbal memory was most impaired. Sixty-two percent of schizophrenia patients were moderately or severely impaired, the corresponding figure for depression was 28%. Impairment was moderately associated with IQ level and clinical symptom load in schizophrenia, but not in depression.

CONCLUSION

Schizophrenia is characterized by deficits across a wide range of NP functions. Thirty-eight percent of the patients are within normal limits. A mild and limited NP disturbance is apparent in depression.

Cortisol level predicts executive and memory function in depression, symptom level predicts psychomotor speed

OBJECTIVE

On a group level depression is related to hypercortisolism and to psychomotor retardation, executive dysfunction and memory impairment. However, intra-group heterogeneity is substantial. Why some are impaired while others remain in the normal range, is not clear. The present study aims at discerning the relative contribution of present symptom severity and hypercortisolism to impairment in the three domains of cognition.

METHOD

Morning saliva cortisol was measured in 26 subjects with recurrent major depression prior to a neuropsychological examination with tests known to be sensitive to cognitive impairment in depression.

RESULTS

Cortisol level correlated with executive dysfunction and post-encoding memory deficits, but not with processing speed. Depression level correlated with processing speed. These patterns remained significant after controlling for confounders through partial correlations.

CONCLUSION

The association between cortisol and cognition is not an artifact of psychiatric symptom load. High level of saliva cortisol is associated with aspects of cognition that can be dissociated from psychomotor retardation, which is dependent on symptom load.

Congenital hypothyroidism: no adverse effects of high dose thyroxine treatment on adult memory, attention, and behaviour

BACKGROUND

In congenital hypothyroidism (CH) it has been questioned whether high dose thyroxine replacement therapy has detrimental effects on memory, attention, and behaviour.

AIMS

To describe memory, attention, and behaviour problems in young adults with CH, and to study possible negative effects of high dose thyroxine replacement therapy.

METHODS

A cohort based follow up study of 49 young adults (mean age 20 years) with early treated CH, and sibling controls (n = 41).

RESULTS

Controlled for age and sex, the CH group attained significantly lower scores than sibling controls on some tests of memory (Wechsler Logical Memory part II: 12.9 versus 17.8; difference 5.2, 95% CI 3.6 to 6.8) and attention (Wechsler Freedom From Distractibility factor: 95.6 versus 104.8; difference 9.9, 95% CI 6.4 to 13.4). They rated themselves with more behaviour problems than did sibling controls (52.7 versus 44.7; difference -7.6, 95% CI -11.2 to -4.0) on the Achenbach Self Report. A high thyroxine starting dose, high serum thyroxine treatment levels during the first six childhood years, and high levels at assessment had no adverse effects on outcome measures at age 20. On the contrary, the results suggest better outcome with higher childhood treatment levels.

CONCLUSIONS

Long term outcome revealed deficits in some aspects of memory, attention, and behaviour in young adults with CH relative to sibling controls. No adverse effects of high dose thyroxine therapy were found on measures of memory, attention, and behaviour problems.

Attention profile in schizophrenia compared with depression: differential effects of processing speed, selective attention and vigilance

OBJECTIVE

The aim of the study is to investigate whether subjects with schizophrenia and major depression display attention deficits for different reasons.

METHOD

Subjects with schizophrenia (n = 53), recurrent major depression (n = 50) and normal controls (n = 50) were administered with 11 measures of processing speed, selective attention and vigilance. Indices of basal speed, speeded attention, non-speeded attention and vigilance were computed.

RESULTS

Both clinical groups were impaired on all chronometric tests. The schizophrenic subjects were also more impaired on speeded attention compared with basal processing speed. Only the schizophrenics were impaired on the non-speeded measures of selective attention. Compared with the schizophrenics, the depressives showed a decrement in vigilance.

CONCLUSION

Reduced performance on attention tests in major depression is because of a non-specific speed reduction and loss of vigilance consistent with lack of effort. In addition to generally impaired processing speed, the schizophrenic subjects exposed a deficit in selective attention, indicating executive dysfunction.

Honig's model of working memory and brain activation: an fMRI study

The present study investigated changes in neuronal activation with fMRI related to Honig's model of working memory, which is much less studied compared with other working memory models. In contrast to other studies which have applied recognition procedures, the primary aim with the present study was to examine brain activation when subjects had to continuously recall and forget items held in working memory. The results showed that the mid-ventrolateral frontal cortex was particularly activated in the left hemisphere, whereas the mid-dorsolateral frontal cortex was particularly activated in the right hemisphere during execution of the working memory task. The findings are discussed in relation to process- and domain-specific accounts of working memory.

Ventricular fibrillation during off-pump coronary artery bypass grafting: transcranial Doppler and clinical findings

A 73-year-old male developed ventricular fibrillation which lasted for 2 min and 24 s, during off-pump coronary artery bypass grafting. Cerebral hemodynamics were assessed by continuous transcranial Doppler monitoring. Ventricular fibrillation resulted in an immediate fall in cerebral blood flow velocities to almost zero with only slight fluctuations. This was then followed by a pronounced reactive hyperperfusion. Cerebral magnetic resonance imaging examinations and detailed neurological and neuropsychological evaluations were performed before and at 3 and 12 months after surgery. No evidence of cerebral damage was found.

Comprehensive driving assessment: neuropsychological testing and on-road evaluation of brain injured patients

The study investigates the correspondence between neuropsychological test results and on-road driving performance among 55 patients with a CT-verified brain damage or documented neurological disorder (cerebrovascular accident: 43, traumatic brain injury: 5, multiple sclerosis: 4, other: 3). 5 patients showed unimpaired test profiles and passed the on-road evaluation. 18 patients showed severe neuropsychological deficits contrary to driving and were not recommended for on-road evaluation. Of the remaining 32 patients with some neuropsychological deficits, all 100% in the minor impaired group (n = 8) passed the driving evaluation, compared to 69% in the mildly impaired (n = 16) and 38% in the moderately impaired group (n = 8). Measures of reduced visuoconstructive ability, reaction time, visual attention, and awareness of cognitive impairments, were found to discriminate between groups. It is concluded that neuropsychological assessment of targeted functions provide an ecological valid prediction of driving skill after brain damage, but that on-road evaluation is needed as supplement in cases with ambiguous test findings.

ERP indicators of disturbed attention in mild closed head injury: a frontal lobe syndrome?

The purpose of the study was to examine the hypothesis that distractibility is a fundamental characteristic of mild closed head injury (MHI). The claim that cognitive symptoms in MHI are due to a mild type of frontotemporal injury was also investigated. Cognitive event-related potentials (ERPs), accuracy and reaction time to target stimuli in a dichotic listening paradigm, and neuropsychological test results were studied in patients with MHI (N = 15), patients with verified frontal lobe damage (N = 10), and healthy controls (N = 13). Information processing reflecting target detection (N2, P3b) and sustained selective attention (processing negativity) was studied. The MHI and frontal patients did not differ on behavioral measures, except that the MHI group had significantly longer reaction times to target stimuli in the ERP task. Both patient groups had deviant ERPs compared with controls, but their ERP patterns differed in important respects. Contrary to expectations, the MHI patients had the most abnormal ERPs. They showed significantly smaller N2 and Nd amplitudes than frontal patients and controls, indicating that the mediating cognitive mechanisms were not equivalent in MHI and frontal injury. The data suggest that MHI patients allocated less processing resources to the task than either the control subjects or the patients with frontal lobe damage.

X linked mental retardation and infantile spasms in a family: new clinical data and linkage to Xp11.4-Xp22.11

In order to describe the neurological abnormalities and to identify the gene localisation, we re-evaluated a previously reported family with X linked mental retardation (XLMR). Reliable data were obtained for six of the seven affected males, of whom two had had infantile spasms. Profound MR (IQ<20) was found in one and mild MR (IQ 50-70) in five males. No dysmorphic features, except for macrocephaly in one male, were found. Neurological abnormalities included varying degrees of spinocerebellar involvement. Neuroimaging studies showed abnormalities, such as cerebellar atrophy or corpus callosum hypoplasia or both, in three of the six males. Several affected and unaffected subjects suffered from hyperhidrosis, which appeared to segregate independently as an autosomal dominant trait. Genetic linkage analysis localised the XLMR disease gene to Xp11.4-Xp22.11 with a maximum multipoint lod score of 3.57, overlapping the candidate region recently found in two Belgian XLMR-infantile spasm families. Compared to the Belgian patients, the majority of the affected males in this report had a considerably milder phenotype.

Auditory laterality and selective attention: normal performance in patients with early-onset schizophrenia

In this study, auditory laterality and selective attention were examined in patients with early-onset schizophrenia using a dichotic listening (DL) test. Deficient performance on this test has repeatedly been found in adult patients with chronic schizophrenia, indicating abnormalities in left hemisphere function. The hypothesis in the present study was that subjects with early-onset schizophrenia manifest deficits in DL test performance similar to adult chronic patients. A group of 19 patients with early-onset schizophrenia were compared with a group of 20 adolescents with attention-deficit hyperactivity disorder and a group of 30 normal adolescents. Results indicated no significant differences between the three groups on any of the measures. Alternative hypotheses are put forth to explain the findings, among them that deficits in DL performance may be secondary to long-time illness and/or drug treatment, and that these deficits may become apparent only after interaction with maturational neurodevelopmental changes during adolescence.

Covert visual attention in patients with early-onset schizophrenia

The aim of the present study is to examine attentional costs (inhibition) in covert visual attention in a group of acutely ill adolescents with schizophrenia without long histories of neuroleptic treatment. Variations in reaction time were analyzed for possible age and sex differences. Adolescents with schizophrenia (n = 19) were compared to a group of ADHD subjects (n = 20) and a group of normally functioning adolescents (n = 30) on a measure of covert visual attention. The results support a hypothesis of abnormally rapid disengagement (reduced costs) in male adolescents with schizophrenia. Such an abnormality has also been found in adults with chronic schizophrenia. Whether this holds true for both sexes of adolescents with schizophrenia or is restricted to male subjects cannot be answered with certainty due to the small number of females with schizophrenia in our sample. Our findings indicate, however, that there are some general sex differences and some specific sex differences related to covert visual attention in adolescents with schizophrenia.

No vigilance deficit found in either young schizophrenic or ADHD subjects

Vigilance deficits have been found in both schizophrenic and ADHD subjects. The two patient groups have never been directly compared on any vigilance measure, however. In the present study 20 early-onset schizophrenics were compared to 20 ADHD adolescents on a Degraded Stimulus Continuous Performance Test (DS-CPT). A comparison group of 30 normal adolescents was also included. Results showed no significant differences between the three groups on any of the DS-CPT measures. Different hypotheses are put forth to explain the findings, among them that the task may be insensitive to identifying sustained attention deficits in adolescent populations.

Backward-masking deficit in adolescents with schizophrenic disorders or attention deficit hyperactivity disorder

OBJECTIVE

Backward masking is a cognitive task that involves the earliest phases of visual information processing. Disrupted task performance caused by a visual mask has been found repeatedly in schizophrenic patients; however, the specificity to schizophrenia of deficits in backward masking has received only limited study.

METHOD

In this study 20 patients with early-onset schizophrenic disorders were compared to 20 adolescents with attention deficit hyperactivity disorder (ADHD) and 30 normal adolescents on a two-digit identification task in three backward-masking conditions: no mask, a short stimulus interval (33.0 msec), and a long stimulus interval (49.5 msec).

RESULTS

The performance of the two groups of patients was similar, and both groups showed a statistically significant masking deficit after the long stimulus interval and a nearly significant deficit after the short stimulus interval in comparison with the normal subjects.

CONCLUSIONS

Increased vulnerability to the masking stimulus was confirmed in schizophrenic subjects, but it is not specific to schizophrenia and is not accounted for by psychotic symptoms alone, since the subjects with ADHD performed similarly.

Production and perception of word tones (pitch accents) in patients with left and right hemisphere damage

The present paper addresses the question of the functional lateralization of tones in tone languages. Tonal perception and production of right-hemisphere-damaged (RHD) and left-hemisphere-damaged (LHD) speakers of East Norwegian were investigated. East Norwegian is a tone language with an opposition between two tones (pitch accents). The ability to distinguish auditorily between the two accents was normal in the RHD group but reduced in the LHD group. Tonal production was near normal in the RHD group, whereas the LHD group tended to have a production deficit.

[Multiple sclerosis and prerequisites for driver's licence. A retrospective study of 33 patients with multiple sclerosis assessed at Sunnaas hospital]

There is increasing interest in assessing the prerequisites for a driver's licence among patients with traumatic brain injury, cerebrovascular accidents and other diseases of the central nervous system which cause cognitive impairments. In the present study, 33 patients with multiple sclerosis, 20 females and 13 males of mean age 43 years, were medically and neuropsychologically examined, and some were assessed in a practical driving test. In total, 19 patients were allowed to drive and 14 were refused. Regression analysis showed that, when deciding for or against driving, cognitive and emotional deficits were given more weight than duration of illness and degree of neurologic deficit. The authors discuss guidelines for assessing the prerequisites for a driver's licence among patients with multiple sclerosis, and indicators for when assessment is warranted.

To drive or not to drive: neuropsychological assessment for driver's license among stroke patients

Seventy-two stroke patients, 43 with right hemisphere (RHD) and 29 with left hemisphere damage (LHD), and 7 coronary infarct controls with no evidence of cerebral damage, were neuropsychologically tested as part of an assessment program for driver's license. Mean age in the group was 53 years. Stroke patients were tested on average 4 months post injury. The groups did not differ on major demographic variables except that RHD patients were more often hemiplegic than LHD patients. The test battery was factor analyzed into 4 valid principal components: (I) visual perception, (II) spatial attention, (III) visuospatial processing, and (IV) language/praxis. The presence of hemianopia (factor I) excludes driving. In addition, measures of neglect and reduced speed of mental processing from factor II, III and IV, were found to be the most discriminating variables when classifying patients for driving. Even though neglect was more frequently observed among RHD than LHD patients, the two hemisphere groups did not differ significantly in number of patients denied driving, 58% RHD compared to 41% LHD patients. The need for comprehensive neuropsychological assessment is underlined.

Neuropsychological predictors in stroke rehabilitation

A mailed questionnaire, sent routinely to discharged stroke patients, divided left-hemisphere (n = 68) and right-hemisphere (n = 77) patients into three groups of general help dependency in basic activities-of-daily-life skills. A subsample of 29 patients was visited at home and asked to reanswer the questionnaire under guidance of a trained occupational therapist. The reliability of the questionnaire was considered satisfactory. Both neurological deficits and neuropsychological syndromes correlated significantly with the level of help needed for managing alone at home. Multiple regression analysis revealed a major gain in explained variance in help dependency when neuropsychological test results were added to information on degree of hemiplegia and hemianopia. Keeping in mind the subject characteristics of the study sample, apraxia and pathological emotional reactions were the more important variables in the left-hemisphere and right-hemisphere groups respectively. The challenge from rehabilitation psychology is discussed and the need for developing more sophisticated methods for assessing rehabilitation potential is stressed.

Sex differences in cognitive impairment following unilateral brain damage

Studies reporting that cognitive activity in women is more bilaterally organized than in men are reviewed. WAIS data from left- and right-sided male and female brain-injured patients are presented. A significant discrepancy score is found between the VIQ and PIQ in the male subsample, but not in the female subsample. The latter is almost equally impaired on the two scales irrespective of side of damage. The clinical usefulness of the discrepancy score is modest, classifying laterality of lesion correctly in less than 70% of patients of either sex. Linear discriminant analysis of the subtests disregarding the verbal-performance dichotomy yielded considerable increase in hit-rate in prediction of laterality of lesion. It is concluded that men and women use different cognitive strategies in solving intellectual problems and that this may explain the sex differences found on the WAIS.