Anhedonia in schizophrenia: a distinct familial subtype?

Neuropsychology and Neurobiology of Negative Schizotypy: A Selective Review

Schizotypy refers to a latent personality organization that reflects liability to schizophrenia. Because schizotypy is a multidimensional construct, people with schizotypy vary in behavioral and neurobiological features. In this article, we selectively review the neuropsychological and neurobiological profiles of people with schizotypy, with a focus on negative schizotypy. Empirical evidence is presented for alterations of neuropsychological performance in negative schizotypy. We also cover the Research Domain Criteria domains of positive valence, social process, and sensorimotor systems. Moreover, we systematically summarize the neurobiological correlates of negative schizotypy at the structural, resting-state, and task-based neural levels, as well as the neurochemical level. The convergence and inconsistency of the evidence are critically reviewed. Regarding theoretical and clinical implications, we argue that negative schizotypy represents a useful organizational framework for studying neuropsychology and neurobiology across different psychiatric disorders.

Anhedonia in Depression and Schizophrenia: Brain Reward and Aversion Circuits

Anhedonia, which is defined as markedly diminished interest or pleasure, is a prominent symptom of psychiatric disorders, most notably major depressive disorder (MDD) and schizophrenia. Anhedonia is considered a transdiagnostic symptom that is associated with deficits in neural reward and aversion functions. Here, we review the characteristics of anhedonia in depression and schizophrenia as well as shared or disorder-specific anhedonia-related alterations in reward and aversion pathways of the brain. In particular, we highlight that anhedonia is characterized by impairments in anticipatory pleasure and integration of reward-related information in MDD, whereas anhedonia in schizophrenia is associated with neurocognitive deficits in representing the value of rewards. Dysregulation of the frontostriatal circuit and mesocortical and mesolimbic circuit systems may be the transdiagnostic neurobiological basis of reward and aversion impairments underlying anhedonia in these two disorders. Blunted aversion processing in depression and relatively strong aversion in schizophrenia are primarily attributed to the dysfunction of the habenula, insula, amygdala, and anterior cingulate cortex. Furthermore, patients with schizophrenia appear to exhibit greater abnormal activation and extended functional coupling than those with depression. From a transdiagnostic perspective, understanding the neural mechanisms underlying anhedonia in patients with psychiatric disorders may help in the development of more targeted and efficacious treatment and intervention strategies.

Personality Traits in Individuals with the Dual Diagnosis of Psychosis and Substance Use Disorders: A Comprehensive Review and Meta-Analysis

Substance abuse comorbidity is highly prevalent and is linked to detrimental outcomes in individuals with psychotic disorder, but the role of personality traits as the underlying mechanism is being increasingly underscored. This study aimed to profile temperamental risks of comorbid substance use disorder in psychotic disorders by performing meta-analyses on personality trait differences between psychotic disorders with comorbidity (dual diagnosis; DD) and without it (psychotic disorders; PSD). Methods: A systematic review of English articles using PubMed, MEDLINE, Scopus, Google Scholar, and ProQuest Dissertation and Theses. Only original empirical studies including participants with diagnosis of psychotic disorders based on structured diagnostic interviews, with and without substance use disorder evaluated with reliable and valid tests were included. Articles were independently extracted by two authors using predefined data fields, including study quality indicators. All pooled analyses were based on random-effect models. Thirteen studies (N = 885) met our inclusion criteria. All effect-size estimates were calculated based on means and standard deviations of included measures. Separate effect size estimates were obtained for four traits in the UPPS model (negative urgency, low premeditation, low perseverance, sensation seeking), four traits in the HS model (unconscientious disinhibition, negative affect, disagreeable disinhibition, positive affect) and trait anhedonia. Results: Negative urgency (four studies with 262 participants; ES = 0.59; 95% confidence interval [CI] [0.34, 0.84]), low premeditation (five studies with 349 participants; ES = 0.60; 95% CI [0.39, 0.80]), sensation seeking (seven studies with 550 participants; ES = 0.63; 95% CI [0.17, 1.09]) and unconscientious disinhibition (five studies with 291 participants; ES = 0.36; 95% CI [0.13, 0.59]) were elevated in DD than PSD. Heterogeneity of sensation seeking was significant (I² = 86.2%). Conclusions: The findings of the current meta-analysis highlight a unique profile of impulsive and externalizing trait personality domains pertaining to DD. The study emphasizes the importance of emotion regulation interventions targeting impulsivity or negative affect (i.e. negative urgency, low premeditation) in substance abuse comorbidity patients.

Abnormal Anhedonia as a Potential Endophenotype in Obsessive-Compulsive Disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is often accompanied by cognitive, particularly executive function, impairments. Recently, anhedonia has emerged as an apparently important symptom of OCD reflecting altered emotion regulation. These two aspects are often comorbid in OCD. However, little is known about whether anhedonia may be a trait marker for OCD.

METHODS

To verify the role of executive function and evaluate the role of anhedonia in OCD and its relationship with OCD symptoms, we recruited 60 OCD patients, 30 unaffected first-degree relatives (FDRs), and 60 healthy controls (HCs). Participants completed psychometric testing to assess depression, anxiety, and anhedonia symptoms, as well as two cognitive tests to assess executive function, namely the Wisconsin Card Sorting Test (WCST) and the Stroop Color-Word Test (SCWT).

RESULTS

Compared to HCs, OCD patients and FDRs had significantly lower anticipatory and consummatory pleasure scores. The severity of anticipatory anhedonia correlated positively with obsessive-compulsive symptoms (r = 0.253, p = 0.009), even after controlling for depression and anxiety symptoms. Compared to HCs, OCD patients and FDRs made more errors and achieved fewer categories in the WCST. For all three SWCT components, OCD patients and FDRs took more time to name colors than HCs, but the three groups had similar numbers of errors.

CONCLUSION

This family-based study showed dampened pleasure together with cognitive dysfunction in OCD patients. The similar consummatory pleasure findings between OCD and FDR groups suggest anhedonia may be considered as a candidate OCD endophenotype.

A study of physical anhedonia as a trait marker in schizophrenia

BACKGROUND

Inability to define the heritable phenotype might be a reason for failure to replicate results in psychiatric genetics. Hence, the use of a candidate symptom approach to identify more homogeneous forms of diseases among affected individuals and subclinical traits among first-degree relatives (FDRs) may increase genetic validity. The objective of the present study was to determine whether physical anhedonia can be used as a marker for individuals at risk of schizophrenia.

MATERIALS AND METHODS

Physical anhedonia scores (measured using Revised Physical Anhedonia Scale [rPAS]) were compared across thirty remitted schizophrenic patients, thirty of their unaffected FDRs, and thirty healthy controls. We compared anhedonia scores among the three main groups using one-way ANOVA.

RESULTS

Physical anhedonia (rPAS) scores of the schizophrenic patient group were significantly higher than that of their FDRs and controls both, and physical anhedonia (rPAS) scores of FDRs were significantly higher than that of healthy controls (F = 115.33, P < 0.001). The subgroups did not differ on various other clinical characteristics.

CONCLUSION

Our data suggest that physical anhedonia is a candidate symptom for schizophrenia.

Social anhedonia and gamma band abnormalities as a composite/multivariate endophenotype for schizophrenia: a dense array EEG study

AIM

Social anhedonia and gamma band oscillations are proposed as a promising endophenotype for schizophrenia (SZ). The aim was to assess whether social anhedonia and spontaneous gamma band oscillations could be used as multivariate/composite endophenotypic measures for SZ.

METHODS

Sixty consented subjects, of which 20 remitted SZ patients, 20 unaffected siblings of patients with schizophrenia (US) and 20 healthy controls (HC) were recruited for the study. The Revised Social Anhedonia Scale, Temporal Experience of Pleasure Scale and the Schizotypal Personality Questionnaire assessed social anhedonia, temporal experience of pleasure and schizotypal features. All participants underwent awake, resting state 192-channel dense array electroencephalographic recording. Gamma spectral power and coherence were calculated. We performed chi-square test, one-way analysis of variance, Pearsons correlation coefficient and step-by-step linear discriminant functional analysis.

RESULTS

Social anhedonia was significantly higher and anticipatory aspects of pleasure were significantly lower in both SZ and US compared with HC. US scored significantly higher than HC in the Schizotypal Personality Questionnaire. Spectral power of high gamma band (>70 Hz) was significantly lower over the right temporo-parietal and midline regions in both SZ and US than HC. We accurately classified (85%) three groups when social anhedonia, high gamma band spectral power of midline, right frontal and right fronto-temporal interhemispheric gamma coherence were considered as composite measures rather than each variable representing independently.

CONCLUSION

We propose region-specific high gamma spectral 'power and coherence' and social anhedonia as composite/multivariate measures could be a useful measure in distinguishing schizophrenia patients and unaffected siblings from healthy controls.

[A history and overview of anhedonia in endogenous mental disorders]

Anhedonia is the inability to experience pleasure. This disorder is heterogeneous across psychiatric disorders and is difficult for measuring and submitting to scientific analysis. Over the last several decades there has been increasing interest in the role that anhedonia plays in various psychopathologies. This article reviews the recent literature on anhedonia and its psychopathological features, which are important for prognosis in affective disorders and schizophrenia. Attempts to dissect various subtypes of anhedonia observed in negative syndrome and depression are reviewed as well.

Anhedonia in schizophrenia: The role of subjective experiences

BACKGROUND

High levels of anhedonia have been found in patients with schizophrenia; specifically they report higher levels of social anhedonia rather than physical anhedonia, and further, in the anticipatory rather than consummatory facets of pleasure. Nonetheless, contrasting results emerged regarding the underlying mechanisms of this deficit. Basic Symptoms (BS) disturb subjective experiences present for most of the illness' course; this impacts patients' daily lives leading to a loss of the ability to organize the experience of the self and the world in a fluid and automatic way. Considering the role played by negative emotions in the subjective evaluation of anhedonia, the aim of the study is to clarify the role of BS in the assessment of anhedonia in a sample of patients with schizophrenia (n=53) compared with healthy controls (n=46).

METHODS

Participants completed a self-administered trait questionnaire evaluating social anhedonia (Revised-Social Anhedonia Scale), physical anhedonia (Physical Anhedonia Scale), and the consummatory and anticipatory pleasure experiences (Temporal Experience of Pleasure Scale). BS were evaluated with the Frankfurter Beschwerde-Frageboden (FBF) whereas psychopathology was assessed with the Positive and Negative Syndromes Scale.

RESULTS

Patients scored higher than healthy controls in social, physical and anticipatory anhedonia, but not in consummatory anhedonia and these relationships were mediated by the FBF. Basic Symptoms of Memory, Overstimulation and Lack of Automatism were related to some facets of anhedonia, independently from depressive symptoms.

CONCLUSIONS

We hypothesize that a subjective cognitive deficit and a reduced ability in information processing, could prevent patients from retaining a positive experience from past pleasant activities. Therefore the lack of pleasure would be, at least in part, related to an avoidance of potentially stressful new scenarios.

Schizotypy and clinical symptoms, cognitive function, and quality of life in individuals with a psychotic disorder

BACKGROUND

Schizotypy is a range of perceptual experiences and personality features related to risk and familial predisposition to psychosis. Despite evidence that schizotypy is related to psychosis vulnerability, very little is known about the expression of schizotypal traits in individuals with a psychotic disorder, and their relationship to clinical symptoms, cognition, and psychosocial functioning.

METHODS

59 healthy subjects and 68 patients with a psychotic disorder (47 schizophrenia spectrum disorder; 21 bipolar disorder with psychotic features) completed four schizotypy scales, the Perceptual Aberration Scale, the Revised Physical and Social Anhedonia Scales, and the Schizotypal Personality Questionnaire, a brief neuropsychological assessment, and a self-report measure of quality of life. Clinical symptoms of psychosis were quantified in patients with the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Psychosis patients scored higher than healthy subjects on all schizotypy scales. Correlations between schizotypy and PANSS scores were modest, ranging from r=.06 to r=.43, indicating that less than 20% of the variance in self-reported schizotypy overlapped with clinical symptoms. After controlling for clinical symptoms, patients with schizophrenia spectrum disorders reported higher levels of cognitive-perceptual disturbances and negative traits than patients with bipolar disorder. Elevated schizotypy was associated with lower cognitive functioning and self-reported quality of life.

CONCLUSIONS

Schizotypal personality traits are markedly elevated in psychotic disorders, especially schizophrenia spectrum disorders, relatively weakly correlated with positive and negative psychotic symptoms, and associated with greater cognitive impairment and lower quality of life. Assessing schizotypy in patients with psychosis may be useful for predicting functional outcome and differential diagnosis.

Differential hedonic experience and behavioral activation in schizophrenia and bipolar disorder

The Kraepelinian distinction between schizophrenia (SZ) and bipolar disorder (BP) emphasizes affective and volitional impairment in the former, but data directly comparing the two disorders for hedonic experience are scarce. This study examined whether hedonic experience and behavioral activation may be useful phenotypes distinguishing SZ and BP. Participants were 39 SZ and 24 BP patients without current mood episode matched for demographics and negative affect, along with 36 healthy controls (HC). They completed the Chapman Physical and Social Anhedonia Scales, Temporal Experience of Pleasure Scale (TEPS), and Behavioral Activation Scale (BAS). SZ and BP showed equally elevated levels of self-report negative affect and trait anhedonia compared to HC. However, SZ reported significantly lower pleasure experience (TEPS) and behavioral activation (BAS) than BP, who did not differ from HC. SZ and BP showed differential patterns of relationships between the hedonic experience and behavioral activation measures. Overall, the results suggest that reduced hedonic experience and behavioral activation may be effective phenotypes distinguishing SZ from BP even when affective symptoms are minimal. However, hedonic experience differences between SZ and BP are sensitive to measurement strategy, calling for further research on the nature of anhedonia and its relation to motivation in these disorders.

Neural substrates underlying effort computation in schizophrenia

The lack of initiative, drive or effort in patients with schizophrenia is linked to marked functional impairments. However, our assessment of effort and motivation is crude, relying on clinical rating scales based largely on patient recall. In order to better understand the neurobiology of effort in schizophrenia, we need more rigorous measurements of this construct. In the behavioural neuroscience literature, decades of work has been carried out developing various paradigms to examine the neural underpinnings of an animal's willingness to expend effort for a reward. Here, we shall review this literature on the nature of paradigms used in rodents to assess effort, as well as those used in humans. Next, the neurobiology of these effort-based decisions will be discussed. We shall then review what is known about effort in schizophrenia, and what might be inferred from experiments done in other human populations. Lastly, we shall discuss future directions of research that may assist in shedding light on the neurobiology of effort cost computations in schizophrenia.

Further evidence for ClockΔ19 mice as a model for bipolar disorder mania using cross-species tests of exploration and sensorimotor gating

Bipolar disorder (BD) is a pervasive neuropsychiatric disorder characterized by episodes of mania and depression. The switch between mania and depression may reflect seasonal changes and certainly can be affected by alterations in sleep and circadian control. The circadian locomotor output cycles kaput (CLOCK) protein is a key component of the cellular circadian clock. Mutation of the Clock gene encoding this protein in ClockΔ19 mutant mice leads to behavioral abnormalities reminiscent of BD mania. To date, however, these mice have not been assessed in behavioral paradigms that have cross-species translational validity. In the present studies of ClockΔ19 and wildtype (WT) littermate mice, we quantified exploratory behavior and sensorimotor gating, which are abnormal in BD manic patients. We also examined the saccharin preference of these mice and their circadian control in different photoperiods. ClockΔ19 mice exhibited behavioral alterations that are consistent with BD manic patients tested in comparable tasks, including hyperactivity, increased specific exploration, and reduced sensorimotor gating. Moreover, compared to WT mice, ClockΔ19 mice exhibited a greater preference for sweetened solutions and greater sensitivity to altered photoperiod. In contrast with BD manic patients however, ClockΔ19 mice exhibited more circumscribed movements during exploration. Future studies will extend the characterization of these mice in measures with cross-species translational relevance to human testing.

Odor hedonic capacity and anhedonia in schizophrenia and unaffected first-degree relatives of schizophrenia patients

OBJECTIVE

There is increasing evidence that schizophrenia patients have difficulties in the hedonic appraisal of odors. In a prior study, we assessed olfactory hedonic perception birhinally and found that males with schizophrenia failed to attach the appropriate hedonic valence to a pleasant odor, despite correctly perceiving changes in odor intensity. Female patients, in contrast, exhibited normal responses. The current study extends this work by examining odor valence processing in unaffected first-degree relatives of schizophrenia patients, to determine the extent to which this abnormality may be genetically mediated. We also examine odor valence processing unirhinally, rather than birhinally, to probe possible lateralized differences in patients' hedonic processing deficits.

METHOD

Individuals with schizophrenia (n = 54), first-degree unaffected family members (n = 22), and demographically matched controls (n = 45) were administered the Suprathreshold Amyl Acetate Odor Intensity and Odor Pleasantness Rating Test.

RESULTS

In contrast to family members and controls, both male and female schizophrenia probands underevaluated the hedonic characteristics of amyl acetate at lower concentrations and overevaluated its pleasantness at concentrations perceived as unpleasant by both controls and relatives. These patient-specific differences could not be explained by differences in smoking habit, medication use, or subjective ratings of odor intensity. However, they were associated with increased levels of anhedonia/asociality and negative symptomatology.

CONCLUSIONS

Our findings suggest that both male and female schizophrenia patients have difficulties in the unirhinal appraisal of hedonic valence. Normal responses in unaffected first-degree relatives suggest that this is an environmentally, rather than genetically, mediated abnormality denoting negative symptomatology.

Self-monitoring as a familial vulnerability marker for psychosis: an analysis of patients, unaffected siblings and healthy controls

BACKGROUND

Alterations in self-monitoring have been reported in patients with psychotic disorders, but it remains unclear to what degree they represent true indicators of familial vulnerability for psychosis.

METHOD

An error-correction action-monitoring task was used to examine self-monitoring in 42 patients with schizophrenia, 32 of their unaffected siblings and 41 healthy controls.

RESULTS

Significant between-group differences in self-monitoring accuracy were found (χ2=29.3, p<0.0001), patients performing worst and unaffected siblings performing at an intermediate level compared to controls (all between-group differences p<0.05). In the combined group of healthy controls and unaffected siblings, detection accuracy was associated with positive schizotypy as measured by the Structured Interview for Schizotypy - Revised (SIS-R) (β=-0.16, s.e.=0.07, p=0.026), but not with negative schizotypy (β=-0.05, s.e.=0.12, p=0.694). In patients, psychotic symptoms were not robustly associated with detection accuracy (β=-0.01, s.e.=0.01, p=0.094), although stratified analysis revealed suggestive evidence for association in patients not currently using antipsychotic medication (β=-0.03, s.e.=0.01, p=0.052), whereas no association was found in patients on antipsychotic medication (β=-0.01, s.e.=0.01, p=0.426). A similar pattern of associations was found for negative symptoms.

CONCLUSIONS

Alterations in self-monitoring may be associated with familial risk and expression of psychosis. The association between psychotic symptoms and self-monitoring in patients may be affected by antipsychotic medication, which may explain previous inconsistencies in the literature.

Limbic response to psychosocial stress in schizotypy: a functional magnetic resonance imaging study

Psychological stress causes dopamine release in the striatum and is thought to play a role in susceptibility to psychotic illness. Previous work suggests that an elevated dopaminergic response to stress may index vulnerability to psychosis in certain individuals. With functional magnetic resonance imaging, we measured stress-induced changes in brain activity in healthy individuals at elevated risk of developing psychosis. Participants were 15 controls and 25 psychometric schizotypes: 12 with positive symptom schizotypy (perceptual aberrations) and 13 with negative symptom schizotypy (physical anhedonia), as determined by questionnaires (Chapman et al., 1976; Chapman and Chapman, 1978). In the scanner, participants performed the Montreal Imaging Stress Task and a matched sensory-motor control task. Measures of self-reported stress and salivary cortisol levels were taken throughout the experiment. All three groups showed significant increases in self-reported stress and significant fMRI signal change in the striatal, limbic and cortical regions. However, the Physical Anhedonia group showed greater stress-induced striatal and limbic deactivation than the other two groups. Deactivation in the striatum was significantly correlated with Physical Anhedonia score across all subjects. Our findings suggest the presence of abnormalities in striatal response to stress in negative symptom schizotypy.

Impairment of emotional expression recognition in schizophrenia: a Cuban familial association study

It is well established that schizophrenia is associated with difficulties in recognizing facial emotional expressions, but few studies have reported the presence of this deficit among their unaffected relatives. This study attempts to add new evidence of familial association on an emotional expression processing test. The study evaluated the performance of 93 paranoid schizophrenia patients, 110 first-degree relatives of probands from multiplex schizophrenia families, and 109 nonpsychiatric controls on a facial emotional recognition test using a computer morphing technique to present the dynamic expressions. The task entailed the recognition of a set of facial expressions depicting the six basic emotions presented in 21 successive frames of increasing intensity. The findings indicated that schizophrenia patients were consistently impaired for the recognition of the six basic facial expressions. In contrast, their unaffected relatives showed a selective impairment for the recognition of disgust and fearful expressions. Familial association of selective facial emotional expressions processing deficit may further implicate promising new endophenotypes that can advance the understanding of affective deficits in schizophrenia.

Associations of anhedonia and cognition in persons with schizophrenia spectrum disorders, their siblings, and controls

The aim of the current study was to investigate the levels of social and physical anhedonia, as measured with the Chapman Scales for social and physical anhedonia in groups of patients with schizophrenia spectrum psychosis (n = 91), their unaffected siblings (n = 105), and control subjects drawn from a general population (n = 67). The second aim was to explore the effect of physical and social anhedonia on neuropsychological variables. Subjects with schizophrenia spectrum disorder had significantly more anhedonia than population controls, but the unaffected siblings did not differ from controls. Subjects with schizophrenia spectrum disorders had generalized cognitive deficits. Unaffected sibling status predicted impairments in executive and performance speed measures. Elevated physical anhedonia associated with deficits in verbal functions, but this was not related to genetic liability to schizophrenia. In conclusion, social and physical anhedonia did not seem to mediate neuropsychological deficits of schizophrenia family members.

Functional neural substrates of self-reported physical anhedonia in non-clinical individuals and in patients with schizophrenia

BACKGROUND

Anhedonia is a negative symptom of schizophrenia that has a detrimental impact on functioning and quality of life. Anhedonia also represents a vulnerability marker for schizophrenia when measured in non-clinical individuals. The investigation of the neural correlates of anhedonia in schizophrenia and non-clinical individuals could provide key insights on the pathophysiology of negative symptoms, as well as on the characterization of neural markers of vulnerability.

METHODS

Thirty patients with schizophrenia and twenty-six non-clinical individuals were recruited. We used an event-related functional Magnetic Resonance Imaging paradigm involving an emotional picture viewing task. For each group, separately, we correlated the regional BOLD signal changes during hedonic processing with the Chapman Physical Anhedonia Scale scores. An interaction analysis identified the neural correlates of anhedonia specific to schizophrenia.

RESULTS

We found that anhedonia severity in both groups was inversely correlated with the activity of a limited number of emotion-related regions, including the medial prefrontal cortex. The orbitofrontal cortex and putamen/ventral striatum activity was negatively correlated with anhedonia severity in people with schizophrenia only.

CONCLUSIONS

The data first suggest that anhedonia severity is linked to a poor modulation of emotional/attentional brain regions during the processing of hedonic information. The link between anhedonia and the activity of the ventral striatum and orbitofrontal cortex found in schizophrenia could reflect the specific impairment of indirect factors, such as reward anticipation deficits, that influence the measurement of anhedonia severity through self-report questionnaires.

Data on schizotypy and affective scales are gender and education dependent--study in the Northern Finland 1966 Birth Cohort

We present psychometric properties and normative data by gender and educational level in scales related to schizotypy and affective disorders in a large population-based adult sample. As part of the 31-year follow-up survey of the Northern Finland 1966 Birth Cohort; Bipolar II scale (BIP2), Hypomanic Personality Scale (HPS), Physical Anhedonia Scale (PAS), Social Anhedonia Scale (SAS), Perceptual Aberration Scale (PER) and Schizoidia Scale (SCHD) were filled in by 4928 subjects. In total sample mean scores were: BIP2 10.59 (3.80), HPS 11.26 (7.03), PAS 14.99 (S.D. 7.03), SAS 9.44 (5.52), PER 2.35 (3.26) and SCHD 2.56 (1.42). Men scored higher (had more psychopathological symptoms) in PAS and SAS (P<0.001), and in BIP2 (P=0.02). Women had higher scores in SCHD, HPS and PER (P<0.001). Participants with a lower level of education scored higher in all scales; differences were largest in BIP2, PAS and SAS (ES>0.5,P<0.001). The gender and education differences were moderate or large in all the included scales. These differences should be taken into account when considering normal values in these scales. The findings indicate that commonly used student samples are likely to be biased when compared to community based samples.

Perceptual/attentional anomalies in schizophrenia: a family study

Endophenotypes have emerged as an important concept in the study of schizophrenia. Perceptual/attentional anomalies were examined as potential endophenotypes in a family study using a strategy for "multiplex/simplex schizophrenia". The sample was comprised of 797 subjects: 206 schizophrenia patients, 302 first-degree relatives and 289 controls. The Spanish versions of the Structured Interview for Assessing Perceptual/attentional Anomalies (SIAPA) and Positive and Negative Symptoms Scale (PANSS) were applied to measure the presence of perceptual/attentional anomalies, and positive and negative subscale respectively. An ANCOVA was carried out for global comparisons between groups. The multiplex schizophrenic group had significantly more frequent auditory and visual perceptual/attentional anomalies than Simplex schizophrenic and control groups. The most interesting finding was that the severity of auditory and visual perceptual/attentional anomalies and negative symptoms was significantly higher in the relatives of the multiplex schizophrenia group than in those relatives from the simplex schizophrenia and control groups. The existence of perceptual/attentional anomalies in nonaffected relatives suggests the presence of familial association for these symptoms which may therefore be a potential endophenotype suitable for genetic studies.

Relative food preference and hedonic judgments in schizophrenia

There is a well-documented disruption of the neural network associated with reward evaluation in schizophrenia. This same system is involved in coding the incentive value of food in healthy individuals, but few studies to date have examined anhedonia and its relation to food hedonicity and preference in schizophrenia. Relative preference and hedonic food ratings were examined in schizophrenia patients and healthy controls. In the relative preference task, subjects viewed photographs of food items and selected the one that they most preferred. Hedonic ratings were obtained by asking subjects how much they liked the food stimulus on a scale of 1-5. There were no overall response time differences between the two groups in the relative preference task, but schizophrenia patients showed subtle differences in their hedonic ratings of foods compared with control subjects. Schizophrenia patients gave more positive hedonic ratings for food than did controls, and the use of fewer positive ratings was associated with increased anhedonia, particularly with loss of sexual interest. These results suggest that while making relative preference judgments may be intact, hedonic values attached to food may be altered in schizophrenia, and they may be related to dysfunction in more basic vegetative systems.

Psychometric properties of the Revised Physical and Social Anhedonia Scales in non-clinical young adults

Anhedonia, a central dimension within the schizotypy construct, has been considered to be a promising vulnerability marker for schizophrenia-spectrum disorders. The Revised Physical Anhedonia Scale (RPhA) and Revised Social Anhedonia Scale (RSAS) are two self-reports widely used in the assessment of anhedonia; however, they psychometric characteristics have been scarcely investigated in Spanish population. The objective of the current work was to study the psychometric properties of the Revised Physical and Social Anhedonia Scales in non-clinical young adults. The sample was composed of 728 college students with a mean age of 20.1 years (SD = 2.5). The data indicated that the scales showed adequate psychometric characteristics. The Cronbach alpha was 0.95 (RSAS) and 0.92 (RPhA) respectively. The confirmatory factor analysis carried out on the matrix of tetrachoric correlations showed that both scales presented an essentially unidimensional solution. The Revised Physical and Social Anhedonia Scales seem to be adequate for psychosis-risk assessment in non-clinical populations. Future research should further investigate the construct validity in other populations and cultures as well as study its relation to emotional aspects and cognitive endophenotypes.

Anhedonia in schizophrenia and major depression: state or trait?

BACKGROUND

In schizophrenia and major depressive disorder, anhedonia (a loss of capacity to feel pleasure) had differently been considered as a premorbid personological trait or as a main symptom of their clinical picture. The aims of this study were to examine the pathological features of anhedonia in schizophrenic and depressed patients, and to investigate its clinical relations with general psychopathology (negative, positive, and depressive dimensions).

METHODS

A total of 145 patients (80 schizophrenics and 65 depressed subjects) were assessed using the Physical Anhedonia Scale and the Social Anhedonia Scale (PAS and SAS, respectively), the Scales for the Assessment of Positive and Negative Symptoms (SAPS and SANS, respectively), the Calgary Depression Scale for Schizophrenics (CDSS), and the Hamilton Depression Rating Scale (HDRS). The statistical analysis was performed in two steps. First, the schizophrenic and depressed samples were dichotomised into 'anhedonic' and 'normal hedonic' subgroups (according to the 'double (PAS/SAS) cut-off') and were compared on the general psychopathology scores using the Mann-Whitney Z test. Subsequently, for the total schizophrenic and depressed samples, Spearman correlations were calculated to examine the relation between anhedonia ratings and the other psychopathological parameters.

RESULTS

In the schizophrenic sample, anhedonia reached high significant levels only in 45% of patients (n = 36). This 'anhedonic' subgroup was distinguished by high scores in the disorganisation and negative dimensions. Positive correlations of anhedonia with disorganised and negative symptoms were also been detected. In the depressed sample, anhedonia reached high significant levels in only 36.9% of subjects (n = 24). This 'anhedonic' subgroup as distinguished by high scores in the depression severity and negative dimensions. Positive correlations of anhedonia with depressive and negative symptoms were also been detected.

CONCLUSION

In the schizophrenic sample, anhedonia seems to be a specific subjective psychopathological experience of the negative and disorganised forms of schizophrenia. In the depressed sample, anhedonia seems to be a specific subjective psychopathological experience of those major depressive disorder forms with a marked clinical depression severity.

Affective traits in schizophrenia and schizotypy

This article reviews empirical studies of affective traits in individuals with schizophrenia spectrum disorders, population-based investigations of vulnerability to psychosis, and genetic and psychometric high-risk samples. The review focuses on studies that use self-report trait questionnaires to assess Negative Affectivity (NA) and Positive Affectivity (PA), which are conceptualized in contemporary models of personality as broad, temperamentally-based dispositions to experience corresponding emotional states. Individuals with schizophrenia report a pattern of stably elevated NA and low PA throughout the illness course. Among affected individuals, these traits are associated with variability in several clinically important features, including functional outcome, quality of life, and stress reactivity. Furthermore, evidence that elevated NA and low PA (particularly the facet of anhedonia) predict the development of psychosis and are detectable in high-risk samples suggests that these traits play a role in vulnerability to schizophrenia, though they are implicated in other forms of psychopathology as well. Results are discussed in terms of their implications for treatment, etiological models, and future research to advance the study of affective traits in schizophrenia and schizotypy.

Stress-induced dopamine release in humans at risk of psychosis: a [11C]raclopride PET study

Drugs that increase dopamine levels in the brain can cause psychotic symptoms in healthy individuals and worsen them in schizophrenic patients. Psychological stress also increases dopamine release and is thought to play a role in susceptibility to psychotic illness. We hypothesized that healthy individuals at elevated risk of developing psychosis would show greater striatal dopamine release than controls in response to stress. Using positron emission tomography and [(11)C]raclopride, we measured changes in synaptic dopamine concentrations in 10 controls and 16 psychometric schizotypes; 9 with perceptual aberrations (PerAb, ie positive schizotypy) and 7 with physical anhedonia (PhysAn, ie negative schizotypy). [(11)C]Raclopride binding potential was measured during a psychological stress task and a sensory-motor control. All three groups showed significant increases in self-reported stress and cortisol levels between the stress and control conditions. However, only the PhysAn group showed significant stress-induced dopamine release. Dopamine release in the entire sample was significantly negatively correlated with smooth pursuit gain, an endophenotype linked to frontal lobe function. Our findings suggest the presence of abnormalities in the dopamine response to stress in negative symptom schizotypy, and provide indirect evidence of a link to frontal function.

The validity of Psychosis Proneness Scales as vulnerability indicators in recent-onset schizophrenia patients

The Psychosis Proneness Scales developed by the Chapmans and colleagues [Chapman, J.P., Chapman, L.J., Kwapil, T.R. Scales for the measurement of schizotypy. In: Raine., A., Lencz, T., Mednick, S.A., (Eds.). Schizotypal Personality. New York: Cambridge University Press, 1995. pp. 79-109] are widely used to identify non-patient individuals who are hypothesized to possess heightened vulnerability to schizophrenia and related psychopathology. Yet surprisingly little is known about whether schizophrenia patients themselves show abnormalities on these scales across different clinical states, as would be expected for vulnerability indicators. Scores on four of the Psychosis Proneness Scales were evaluated at three assessment points over a 15-month period in healthy controls (n=54) and in recent-onset schizophrenia patients (n=72) who experienced symptom fluctuations across assessments. Patients showed steady elevations on the Physical Anhedonia Scale across time and clinical state, consistent with a stable vulnerability indicator. Patients had higher scores on the Perceptual Aberration and Magical Ideation Scales than controls throughout the follow-up period but scores also changed across clinical states, consistent with a mediating vulnerability indicator. Patients had higher scores on the Impulsive Non-Conformity Scale than controls only during a psychotic state, reflecting an episode indicator. The longitudinal characteristics of these scales in people who are actually diagnosed with schizophrenia provide key evidence for the validity of three commonly used psychometric indicators of vulnerability to psychosis.

No evidence for physical anhedonia as a candidate symptom or an endophenotype in bipolar affective disorder

OBJECTIVES

Bipolar affective disorder (BPAD) is clinically and genetically heterogeneous and the affected phenotype is poorly defined, hampering studies of its genetic basis. Studies of specific, familial, clinical indicators of BPAD may be useful for identifying heritable forms. Homogeneous forms of the disease may be identified in patients (candidate symptom approach) and some vulnerability markers may be sought in unaffected relatives of patients (intermediate traits or endophenotypes). Physical anhedonia (PA) is considered a possible candidate symptom and endophenotype in schizophrenia, but has never been specifically investigated in BPAD.

METHODS

Physical anhedonia scores (measured using Chapman's Physical Anhedonia Scale) were compared in 351 euthymic bipolar patients, 130 of their first-degree relatives and 170 healthy controls with no personal or familial history of schizophrenia, mood disorders or suicidal behavior. We investigated intrafamilial resemblance of PA and compared the progressive and clinical characteristics of hedonic and anhedonic bipolar probands.

RESULTS

Physical anhedonia was a stable trait in normothymic bipolar patients and significant intrafamilial correlation of PA scores was observed in bipolar families. However, PA scores were similar in unaffected relatives and controls and the clinical characteristics of anhedonic and hedonic patients did not differ significantly. Physical anhedonia was not associated with an increased familial risk for bipolar disorder.

CONCLUSIONS

Physical anhedonia is a stable, familial dimension in BPAD families. It cannot be considered an endophenotype because unaffected relatives of bipolar patients and healthy controls have similar PA scores. It also cannot be considered a candidate symptom because it does not identify a homogeneous clinical and familial sub-group of bipolar patients. Given the results of previous studies, PA might be a specific candidate symptom (and endophenotype) to schizophrenia. However, the validation of this hypothesis requires replication studies in bipolar disorder and schizophrenia and further investigations in other psychiatric diseases (in particular across the mood disorder spectrum).

The significance of family history in first-episode schizophrenia spectrum disorder

There have been inconsistent findings regarding the significance of family history of schizophrenia spectrum disorders in relation to presentation and course of illness. There has been little research relevant to this issue from first-episode patients. We examined the differences in premorbid adjustment, symptoms, and intellectual functioning between 28 first-episode schizophrenia spectrum patients with a history of such illness in first degree relatives and 28 matched patients without such a family history. The results indicate that whereas the 2 groups did not differ in presenting symptoms, those with a positive family history showed poorer intellectual functioning and less reduction in symptoms at 2 and 3 year follow-up and greater likelihood of abnormal electroencephalogram findings. The findings provide evidence that presence of a positive family history in first-episode patients is associated with a more pernicious form of illness.

Individual differences in trait anhedonia: a structural and functional magnetic resonance imaging study in non-clinical subjects

Anhedonia, the reduced capacity to gain pleasure from pleasurable experiences, is a key symptom of major depression and schizophrenia. Reduced hedonic capacity can also be measured as an enduring trait in non-clinical subjects. Such altered hedonic capacity is likely the result of a basic neuropsychophysiological dysfunction and a vulnerability marker that potentially precedes and contributes to the liability of developing psychiatric disorders. The characterization of the structural and functional neural correlates of trait anhedonia in non-clinical individuals may provide new insights for the early detection of such psychiatric diseases. Twenty-nine non-clinical subjects were scanned at the Montreal Neurological Institute. Trait anhedonia was measured using the Chapman Revised Physical Anhedonia Scale. Semi-automated and automated structural MRI segmentation techniques were used to explore structural correlates of trait anhedonia. Seventeen of the 29 subjects also underwent a functional imaging task where responses to the viewing of affective stimuli were examined to identify the functional correlates of trait anhedonia. Trait anhedonia was inversely related to anterior caudate volume, but positively related to ventromedial prefrontal cortex activity during the processing of positive information. These findings may reflect a specific kind of vulnerability for the development of psychiatric affective disorders and suggest that trait anhedonia may be linked to a volumetric reduction in the basal ganglia and to a prefrontal functional abnormality during hedonic processing.

Anhedonia in schizophrenia

This review highlights key issues and recent progress in understanding the epidemiology, phenomenology, etiology, and treatment of anhedonia in schizophrenia. A reduced pleasure capacity has been recognized as an important feature of the illness since the time of Kraepelin and Bleuler. However, it remains poorly understood for many reasons, including the phenotypic heterogeneity of schizophrenia, the multidimensionality and multifactorial etiology of anhedonia, and the difficulties inherent in the scientific analysis of subjective emotional experiences. We do know that anhedonia is common in schizophrenia, that it has significant negative consequences, and that current treatments are insufficient. Better assessment tools, greater understanding of biological and psychosocial mechanisms, and novel pharmacologic and psychosocial interventions are sorely needed. Anhedonia has received increasing attention in recent years, and there is optimism that the new Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative on negative symptoms will catalyze rapid progress in the near future.

Animal models of depression in drug discovery: a historical perspective

Over the course of the last 50 years many models of major depressive disorder have been developed on the basis of theoretical aspects of this disorder. These models and procedures have been crucial in the discovery and development of clinically-effective drugs. Notwithstanding, there is presently great concern about the discrepancy between positive outcomes of new candidate drugs in animal models and apparent lack of efficacy in humans i.e., the predictive validity of animal models. Some reasons for this concern lie in the over-reliance in the face value of behavioural models, design of clinical trials, placebo responses, genetic variations in response to drugs, species differences in bioavailability and toxicology, and not least, disinterest of pharmaceutical sponsors to continue developing certain drugs. Present model development is focusing on endophenotypic aspects of behaviours rather than trying to model whole syndromes. This essay traces the origins and theoretical bases of our animal models of depression or depressed-like behaviours in humans and indicates how they have evolved from behavioural assays used to measure the potency and efficacy of potential candidate drugs to tools by which endophenotypes of depression may be identified and verified pharmacologically. A cautionary note is included though to indicate that the true predictive validity of our models will not be fully assessed until we can determine the attrition rate of molecules discovered from new drug targets translating into clinically-effective drugs.

Anhedonia in schizophrenia: a review of assessment strategies

Anhedonia, the diminished capacity to experience pleasant emotions, is a common, treatment-resistant feature of schizophrenia that is often included among the negative symptoms of this disorder. This selective review describes the 3 most commonly used approaches to assess anhedonia in schizophrenia: interview-based measures, self-report trait questionnaires, and laboratory-based assessments of emotional experience. For each assessment approach, psychometric properties, relationships to other symptoms and features of schizophrenia, and relationships with the other assessment approaches are evaluated. It is concluded that anhedonia can be reliably assessed and constitutes a distinctive, clinically important aspect of schizophrenia that should be included in a comprehensive evaluation of negative symptoms. Current efforts to define more precisely the nature of the hedonic deficit in schizophrenia are discussed, and recommendations for optimal assessment of anhedonia in clinical trials of novel treatments for negative symptoms are provided.

Schizotypal dimensions: continuity between schizophrenia and bipolar disorders

BACKGROUND

Family studies have suggested that schizophrenia and bipolar disorders share some susceptibility factors. Schizotypal personality disorder (SPD) may be an intermediate phenotype common both to schizophrenia and bipolar disorders. We explored the familiality of schizotypal dimensions by comparing the magnitude of schizotypal dimensions between schizophrenic and bipolar relatives. We also looked for intra-familial resemblance for these dimensions, and for an increased familial risk of schizophrenia and/or bipolar disorders associated with a particular schizotypal dimension.

METHODS

We used the Schizotypal Personality Questionnaire (SPQ) to study the three schizotypal dimensions (disorganization, negative and positive) in a sample of unaffected first-degree relatives of schizophrenic (N=85), psychotic bipolar (N=63) and bipolar (N=32) probands. Differences between groups were tested using a two-tailed t-test or ANOVA for continuous variables and a chi-squared test for discrete variables. We used the intraclass correlation method to study the intra-familial correlation. Linear mixed models were used to measure the familial risk.

RESULTS

The disorganization dimension appears to be common to relatives of both schizophrenia and psychotic bipolar disorders, but not in the relatives of non-psychotic bipolar probands. This dimension also increases the familial risk of these two disorders. The negative dimension shows intra-familial resemblance (R=0.29), we failed to observe the expected familiality for the disorganized dimension.

CONCLUSIONS

The shared nature of the disorganization dimension shown by a similar familial risk for schizophrenia and psychotic bipolar disorders suggests that same genetic background may underlie psychotic disorders. Although, negative dimension is familial, it is not associated for an increased familial risk for both disorders.

Blinking and schizotypal thinking

Spontaneous eye blink rate (SBR) is thought to be a biological marker for cerebral dopamine (DA) activity. Accordingly, positive psychotic symptoms have been found to be associated with an increased SBR and negative psychotic symptoms with a decreased SBR. However, modulations of the DA system in patient populations also result from prior neuroleptic treatment. Here, we tested the possible relationship between SBR and positive and negative schizotypal thought. To test the direct influence of DA on SBR in general and as a function of schizotypy, half of a sample of 40 healthy men received levodopa and the other half placebo in a double-blind procedure. SBR did not differ between substance groups suggesting that a pharmacologically induced DA increase in healthy individuals does not generally increase SBR. However, in the levodopa group, increasing SBR correlated with increasing negative schizotypy scores, while no relationship was found between SBR and (1) negative schizotypy in the placebo group, or (2) positive schizotypy in either substance group. We conjecture that a pre-existing hypodopaminergic state in high negative schizotypy scorers, made these individuals susceptible to an increased DA concentration, as it has been observed in Parkinson's disease. Furthermore, the absence of any relationship in the placebo group might suggest that variations in DA concentration as a function of schizotypy are too subtle to influence SBR. Finally, the lack of any association of SBR with positive schizotypy might indicate that SBR and positive schizotypy are mediated by functionally distinct neural circuits.

Antisaccade and smooth pursuit performance in positive- and negative-symptom schizotypy

Schizophrenic patients have well-documented abnormalities in smooth pursuit eye movements and antisaccade performance. In populations at risk for schizophrenia, smooth pursuit abnormalities are also well documented. Antisaccade deficits have been replicated in high-risk populations as well, but the findings are more variable and the reasons for the variability are not clear. Some evidence suggests that antisaccade deficits increase in high-risk populations in relation to the presence of positive symptoms. Whether antisaccade deficits increase in relation to negative symptoms in high-risk populations is relatively uninvestigated. We evaluated antisaccade and pursuit performance in "psychometric schizotypes" who had elevated scores on either the Perceptual Aberration Scale (PerAb; i.e., positive symptoms) or the Physical Anhedonia Scale (PhysAnh; i.e., negative symptoms) but not both, and in normal controls. We used the standard version of the antisaccade task, for which results in positive-symptom schizotypes have previously been reported, and investigated performance on a gap and overlap version. We replicated the finding that a significantly larger percentage of positive-symptom schizotypes than controls have elevated antisaccade error rates on the standard antisaccade task (P=0.03); the percentage of negative-symptom schizotypes with elevated antisaccade error rates did not differ from that of control subjects. Neither schizotypal group was impaired on the gap or overlap versions of the task. On the pursuit task, a higher percentage of positive- and negative-symptom schizotypes were classified as having deviant performance than control subjects (both Ps<0.04). These findings suggest that antisaccade deficits may be better at identifying high-risk subjects with positive symptoms. Pursuit deficits identified both positive- and negative-symptom schizotypes, but was better at identifying the latter.

Change in the relationship between anhedonia and functional deficits over a 20-year period in individuals with schizophrenia

Although early theorists suggested that deficits in emotional experience be considered a hallmark characteristic of schizophrenia, there has been limited research, and inconsistent findings, on the relationship between anhedonia and functional capacity in individuals after the onset of schizophrenia. Stronger relationships have typically been reported for chronic samples in contrast to first episode samples, although it is not clear whether this is due to selection biases that influence recruitment in these different groups, or whether results reflect a change over the course of illness. The current longitudinal study examined the relationship between physical anhedonia and functional status in a sample of 61 individuals with schizophrenia at regular intervals over a 20-year period. Subjects were recruited into the study during an index hospitalization and completed assessments at 2-, 4.5-, 7.5-, 10-, 15-, and 20-year follow-ups. Analyses indicate that the relationship between anhedonia and impairments increases over time, although mean performance on these measures is stable across this same time period. These results suggest increasing convergence of impairments in emotional, adaptive, and cognitive capacities over time, with physical anhedonia associated with poorer outcome.