Cognitive performance in presumed obligate carriers for psychosis

Mismatch negativity amplitude in first-degree relatives of individuals with psychotic disorders: Links with cognition and schizotypy

Mismatch negativity (MMN) amplitude is reliably reduced in psychotic disorders. While several studies have examined this effect in first-degree relatives of individuals with schizophrenia, few have sought to quantify deficits in relatives of individuals with other psychotic disorders. While some conclude that, compared to healthy subjects, first-degree relatives of schizophrenia show reduced MMN, others contradict this finding. Furthermore, though MMN is often shown to be associated with cognitive impairments and clinical symptoms in psychotic disorders, to our knowledge no studies have sought to fully examine these relationships in studies of first-degree relatives. The present study sought to clarify the extent of MMN amplitude reductions in a large sample of siblings of individuals with diverse psychotic disorders (n = 67), compared to probands with psychosis (n = 221) and never psychotic comparison subjects (n = 251). We further examined associations of MMN amplitude with cognition and schizotypal symptoms across these groups. We found that MMN amplitude was intact in siblings compared to probands. MMN amplitude was associated with cognition and schizotypal symptoms dimensionally across levels of familial risk. The present results imply that MMN reductions do not reflect genetic risk for psychotic disorders per se, and instead emerge as a result of, or in conjunction with, clinical features associated with psychosis. Such findings carry important implications for the utility of MMN amplitude as an indicator of inherited risk, and suggest that this component may be best conceptualized as an endophenotype for clinical symptoms and cognitive impairments, rather than risk for psychosis per se.

Delusional ideation, manic symptomatology and working memory in a cohort at clinical high-risk for psychosis: A longitudinal study

We followed up a cohort (n = 35) of clients with an “At Risk Mental State” (ARMS) for almost 2 years (mean 21.3 months). At baseline, these clients had taken part in research looking at the relationship between reasoning biases, memory, personality styles and delusional ideation. During the follow-up period, clients underwent a package of intervention from a specialist early detection team. Eighty percent (n = 28) of these clients were successfully re-interviewed. There was improvement across the cohort as a whole, however five participants (17.9%) had made the transition to psychosis at follow-up. Those who had become psychotic had lower levels of manic symptomatology at baseline than those who did not enter the first episode. Further, across the cohort, impaired working memory and delusional ideation at baseline combined to predict 45% of the delusional ideation at follow-up. These preliminary findings suggest that working memory impairments may be linked to the persistence of delusional ideation and that manic symptoms in someone with an ARMS may suggest that such an individual is less likely to develop a frank psychotic episode.

IQ, the Urban Environment, and Their Impact on Future Schizophrenia Risk in Men

Exposure to an urban environment during early life and low IQ are 2 well-established risk factors for schizophrenia. It is not known, however, how these factors might relate to one another. Data were pooled from the North Jutland regional draft board IQ assessments and the Danish Conscription Registry for men born between 1955 and 1993. Excluding those who were followed up for less than 1 year after the assessment yielded a final cohort of 153170 men of whom 578 later developed a schizophrenia spectrum disorder. We found significant effects of having an urban birth, and also experiencing an increase in urbanicity before the age of 10 years, on adult schizophrenia risk. The effect of urban birth was independent of IQ. However, there was a significant interaction between childhood changes in urbanization in the first 10 years and IQ level on the future adult schizophrenia risk. In short, those subjects who moved to more or less urban areas before their 10th birthday lost the protective effect of IQ. When thinking about adult schizophrenia risk, the critical time window of childhood sensitivity to changes in urbanization seems to be linked to IQ. Given the prediction that by 2050, over 80% of the developed world's population will live in an urban environment, this represents a major future public health issue.

Reciprocal causation models of cognitive vs volumetric cerebral intermediate phenotypes for schizophrenia in a pan-European twin cohort

In aetiologically complex illnesses such as schizophrenia, there is no direct link between genotype and phenotype. Intermediate phenotypes could help clarify the underlying biology and assist in the hunt for genetic vulnerability variants. We have previously shown that cognition shares substantial genetic variance with schizophrenia; however, it is unknown if this reflects pleiotropic effects, direct causality or some shared third factor that links both, for example, brain volume (BV) changes. We quantified the degree of net genetic overlap and tested the direction of causation between schizophrenia liability, brain structure and cognition in a pan-European schizophrenia twin cohort consisting of 1243 members from 626 pairs. Cognitive deficits lie upstream of the liability for schizophrenia with about a quarter of the variance in liability to schizophrenia explained by variation in cognitive function. BV changes lay downstream of schizophrenia liability, with 4% of BV variation explained directly by variation in liability. However, our power to determine the nature of the relationship between BV deviation and schizophrenia liability was more limited. Thus, while there was strong evidence that cognitive impairment is causal to schizophrenia liability, we are not in a position to make a similar statement about the relationship between liability and BV. This is the first study to demonstrate that schizophrenia liability is expressed partially through cognitive deficits. One prediction of the finding that BV changes lie downstream of the disease liability is that the risk loci that influence schizophrenia liability will thereafter influence BV and to a lesser extent. By way of contrast, cognitive function lies upstream of schizophrenia, thus the relevant loci will actually have a larger effect size on cognitive function than on schizophrenia. These are testable predictions.

Prefrontal deviations in function but not volume are putative endophenotypes for schizophrenia

This study sought to systematically investigate whether prefrontal cortex grey matter volume reductions are valid endophenotypes for schizophrenia, specifically investigating their presence in unaffected relatives, heritability, genetic overlap with the disorder itself and finally to contrast their performance on these criteria with putative neuropsychological indices of prefrontal functioning. We used a combined twin and family design and examined four prefrontal cortical regions of interest. Superior and inferior regions were significantly smaller in patients. However, the volumes of these same regions were normal in unaffected relatives and therefore, we could confirm that such deficits were not due to familial effects. Volumes of the prefrontal and orbital cortices were, however, moderately heritable, but neither shared a genetic overlap with schizophrenia. Total prefrontal cortical volume reductions shared a significant unique environmental overlap with the disorder, suggesting that the reductions were not familial. In contrast, prefrontal (executive) functioning deficits were present in the unaffected relatives, were moderately heritable and shared a substantial genetic overlap with liability to schizophrenia. These results suggest that the well recognized prefrontal volume reductions are not related to the same familial influences that increase schizophrenia liability and instead may be attributable to illness related biological changes or indeed confounded by illness trajectory, chronicity, medication or substance abuse, or in fact a combination of some or all of them.

Increase in harm avoidance by genetic loading of schizophrenia

BACKGROUND

Schizophrenia is highly familial neuropsychiatric disorder with heritability estimated at 60% to 90%. Even unaffected first-degree relatives of schizophrenia manifested some neuropsychologic abnormalities, neurologic soft sign, and morphologic anomalies. Because personality traits are under genetic influence and considerable heritability, we intended to evaluate temperament and character of first-degree relatives of schizophrenia and the influence of schizophrenia genetic loading on their temperament and character.

METHODS

Temperament and Character Inventory was completed by 97 first-degree relatives of schizophrenia or schizoaffective disorder, 48 schizophrenic probands (44 patients with schizophrenia and 4 patients with schizoaffective disorder), and 106 control subjects. Within first-degree relatives, parents who have additional probands with schizophrenia spectrum disorder in their ascendant or collateral pedigree and siblings who have offspring with schizophrenia spectrum disorder were defined as presumed carriers (n = 20). Group differences in Temperament and Character Inventory scores were compared using a mixed-model analysis of variance with family as a random effect and age as a covariate.

RESULTS

Harm avoidance (HA) scores increased in the order of control subjects, the first-degree relatives, and probands. Among the relatives, presumed carriers, but not presumed noncarriers, had higher HA compared with control subjects. In addition, probands showed significantly low reward dependence, low self-directedness, and low cooperativeness scores compared with the first-degree relatives and control subjects. Probands had also higher self-transcendence scores than the first-degree relatives and had lower persistence scores than control subjects.

CONCLUSIONS

Our findings that HA increases in proportion to the genetic loading of schizophrenia suggest that it may be a potential endophenotype of schizophrenia.

The imprinted brain: how genes set the balance between autism and psychosis

The imprinted brain theory proposes that autism spectrum disorder (ASD) represents a paternal bias in the expression of imprinted genes. This is reflected in a preference for mechanistic cognition and in the corresponding mentalistic deficits symptomatic of ASD. Psychotic spectrum disorder (PSD) would correspondingly result from an imbalance in favor of maternal and/or X-chromosome gene expression. If differences in gene expression were reflected locally in the human brain as mouse models and other evidence suggests they are, ASD would represent not so much an 'extreme male brain' as an extreme paternal one, with PSD correspondingly representing an extreme maternal brain. To the extent that copy number variation resembles imprinting and aneuploidy in nullifying or multiplying the expression of particular genes, it has been found to conform to the diametric model of mental illness peculiar to the imprinted brain theory. The fact that nongenetic factors such as nutrition in pregnancy can mimic and/or interact with imprinted gene expression suggests that the theory might even be able to explain the notable effect of maternal starvation on the risk of PSD - not to mention the 'autism epidemic' of modern affluent societies. Finally, the theory suggests that normality represents balanced cognition, and that genius is an extraordinary extension of cognitive configuration in both mentalistic and mechanistic directions. Were it to be proven correct, the imprinted brain theory would represent one of the biggest single advances in our understanding of the mind and of mental illness that has ever taken place, and would revolutionize psychiatric diagnosis, prevention and treatment - not to mention our understanding of epigenomics.

Memory functioning in familial bipolar I disorder patients and their relatives

OBJECTIVE

The aim of this study was to compare the memory function of patients with familial bipolar I disorder (BD I) who had shown psychotic features, their non-psychotic, non-bipolar first-degree relatives, and normal controls.

METHOD

We assessed 38 patients with a lifetime diagnosis of BD I who had experienced psychotic symptoms, 49 of their non-psychotic, non-bipolar first-degree relatives, and 44 controls. Patients and relatives were from families multiply affected with functional psychotic illness. A five-subtest short form of the Wechsler Adult Intelligence Scale-Revised and three Wechsler Memory Scale subtests were administered to all participants.

RESULTS

BD I patients showed deficits in verbal memory and verbal learning but not in visual memory. Compared to controls, relatives showed worse verbal learning at a statistically significant or suggestive level and performed significantly worse in both immediate and delayed verbal memory. Similar to patients, there were no differences between the relatives and control group for visual memory.

CONCLUSION

Impaired verbal memory and learning were found in patients and their relatives. These deficits may represent candidate endophenotypic markers for bipolar disorder.

Psychosis and autism as diametrical disorders of the social brain

Autistic-spectrum conditions and psychotic-spectrum conditions (mainly schizophrenia, bipolar disorder, and major depression) represent two major suites of disorders of human cognition, affect, and behavior that involve altered development and function of the social brain. We describe evidence that a large set of phenotypic traits exhibit diametrically opposite phenotypes in autistic-spectrum versus psychotic-spectrum conditions, with a focus on schizophrenia. This suite of traits is inter-correlated, in that autism involves a general pattern of constrained overgrowth, whereas schizophrenia involves undergrowth. These disorders also exhibit diametric patterns for traits related to social brain development, including aspects of gaze, agency, social cognition, local versus global processing, language, and behavior. Social cognition is thus underdeveloped in autistic-spectrum conditions and hyper-developed on the psychotic spectrum.;>We propose and evaluate a novel hypothesis that may help to explain these diametric phenotypes: that the development of these two sets of conditions is mediated in part by alterations of genomic imprinting. Evidence regarding the genetic, physiological, neurological, and psychological underpinnings of psychotic-spectrum conditions supports the hypothesis that the etiologies of these conditions involve biases towards increased relative effects from imprinted genes with maternal expression, which engender a general pattern of undergrowth. By contrast, autistic-spectrum conditions appear to involve increased relative bias towards effects of paternally expressed genes, which mediate overgrowth. This hypothesis provides a simple yet comprehensive theory, grounded in evolutionary biology and genetics, for understanding the causes and phenotypes of autistic-spectrum and psychotic-spectrum conditions.

Selective attention deficits reflect increased genetic vulnerability to schizophrenia

BACKGROUND

Impairment in attention is prominent in schizophrenia and may be a valuable genetic indicator for vulnerability to this disease.

AIMS

We set out to characterize the attention deficits that may be associated with genetic liability to schizophrenia.

METHODS

We compared attention performance in 55 people with schizophrenia, 95 of their first-degree relatives, and 61 unrelated controls. We also segregated presumed obligate carriers of genetic risk (POCs, N=12) and compared their performance with that of controls.

RESULTS

Although the relatives of people with schizophrenia did not significantly differ from the normal controls on the tasks of attention, their scores were significantly ordered such that patients>relatives>normal controls during tasks of sustained and selective attention as measured by the Jonckheere-Terpstra Test (p<.05). Additionally, POCs were significantly worse than normal controls during selective attention tasks such as the Stroop (p=.03) and Letter Cancellation Task (p=.04).

CONCLUSIONS

Heterogeneity in the first-degree relatives may have diluted the attention deficits present in those who are at genetic risk for schizophrenia. On the other hand, our findings in the more homogeneous group of POCs suggest that selective attention may be an indicator of genetic liability for schizophrenia.

Evidence of normal hearing laterality in familial schizophrenic patients and their relatives

Dichotic listening (DL) has been used as a tool to investigate possible left cerebral dysfunction in schizophrenia. However, the wide range of DL tests (e.g., words, emotions, sentences) as well as patient groups ("heterogeneity") has introduced several confounders. Assessing relatives of patients with schizophrenia may overcome some of these problems, and may be more useful in determining if loss of functional cerebral laterality in schizophrenia is a state or a trait phenomenon. The fused consonant-vowel DL test was administered to 114 subjects: 20 individuals with familial schizophrenia, 42 of their healthy relatives, and 52 healthy volunteers. We did this to investigate whether the normal language processing asymmetry-a right ear advantage (REA)-is present, and whether it could serve as a marker for genetic liability. General performance accuracy level was lower in schizophrenia patients and their relatives but the expected REA was present in all groups. Adjusting for age, accuracy, and obligate status made no difference. In conclusion, familial schizophrenic patients and their relatives have normal REA and hearing laterality on the fused DL test.

Where do eating disorders lie on the diagnostic spectrum and what does it mean?

The aim of this paper is to review the concept of comorbidity as it pertains to eating disorders. The historical framing of eating disorders within medicine and psychiatry is described and then we move to what is understood by comorbidity in the current context of diagnostic compendiums. The issue of comorbidity highlights the unsatisfactory nature of the current description of illness phenotypes. There is a move to look for broader and more specific concepts such as that of endophenotypes, for example, in relationship to neuropsychology, and the response to reward and emotion. Finally, we consider how this approach may map onto treatment. For example, it may be necessary to have specific modules tailored to the relevant moderating and mediating factors.