This issue contains two review articles, sets of papers examining various aspects of schizophrenia, dementia and cognitive impairment and eating disorders, and individual articles examining verbal intelligence and therapy outcomes.

Background. According to the self-medication hypothesis, schizophrenia patients would abuse psychoactive substances to get a relief from their negative symptoms. Studies testing the self-medication hypothesis in dual diagnosis (DD) schizophrenia have not been conclusive, with some studies showing that DD patients experience fewer negative symptoms, whereas other studies have failed to detect such differences. One potential confounding factor for this discrepancy lies in the diverse scales used to evaluate the negative symptoms. A systematic quantitative review of the literature using computerized search engines has been undertaken.

Method. Studies were retained in the analysis if: (i) they assessed negative symptoms using the SANS; (ii) groups of schizophrenia patients were divided according to substance use disorders (alcohol, amphetamines, cannabis, cocaine, hallucinogens, heroin and phencyclidine).

Results. Attainable published studies were screened. According to our inclusion criteria, 18 possible studies emerged. Data from 11 studies were available for mathematical analysis. A moderate effect size (total n=1135, 451 DD, 684 single diagnosis, adjusted Hedges' g=–0·470, p=0·00001) was obtained, within a random-effect model, suggesting that DD patients experience fewer negative symptoms. Groups did not differ in age, sex, and positive/general psychopathology.

Conclusions. Using narrow criteria (e.g. SANS), the results of this meta-analysis show that schizophrenia patients with a substance use disorder experience fewer negative symptoms than abstinent schizophrenia patients. As such, these results suggest either that substance abuse relieves the negative symptoms of schizophrenia or that the patients with fewer negative symptoms would be more prone to substance use disorders.

Background. Behavioural brain reserve is a property of the central nervous system related to sustained and complex mental activity which can lead to differential expression of brain injury. Behavioural brain reserve has been assessed using autobiographical data such as education levels, occupational complexity and mentally stimulating lifestyle pursuits. So far there have been several epidemiological reports but no systematic review to put conflicting results into context. Our aim was to quantitatively review evidence for the effect of brain reserve on incident dementia.

Method. Cohort studies of the effects of education, occupation, premorbid IQ and mental activities on dementia risk were of interest. Abstracts were identified in MEDLINE (1966–September 2004), CURRENT CONTENTS (to September, 2004), PsychINFO (1984–September 2004), Cochrane Library Databases and reference lists from relevant articles. Twenty-two studies met inclusion criteria. Key information was extracted by both reviewers onto a standard template with a high level of agreement. Studies were combined through a quantitative random-effects meta-analysis.

Results. Higher brain reserve was associated with a lowered risk for incident dementia (summary odds ratio, 0·54; 95% confidence interval, 0·49–0·59). This effect was found over a median of 7·1 years follow-up and resulted from integrating data across more than 29000 individuals. Notably, increased complex mental activity in late life was associated with lower dementia rates independent of other predictors; a dose–response relationship was also evident between extent of complex mental activities in late life and dementia risk.

Conclusions. This study demonstrates robust evidence that complex patterns of mental activity in the early, mid- and late-life stages is associated with a significant reduction in dementia incidence. Randomized control trials based on brain-reserve principles are now required.

Objectives. Depression is a frequent feature of schizophrenia but the cognitive processes involved in its development and maintenance are unclear. Recent studies have shown that clinical depression is associated with faulty inhibitory mechanisms of selective attention for negative information. The current study examined whether patients with schizophrenia also have an attentional bias towards negative stimuli. The inhibitory processes of interference control and task-shifting abilities were also examined to assess whether patients would show a selective impairment.

Method. Forty-three patients with schizophrenia and 24 healthy controls completed the Affective Shifting Task.

Results. As a group, schizophrenia patients did not show an attentional bias for negative material. However, those patients with high levels of depression demonstrated faster latencies when negative words were the targets, and higher depression scores were found to be associated with an increasing number of false alarms for negative words when they were not the targets. The results also showed that patients had impaired interference control but intact task-shifting abilities.

Conclusions. Faulty inhibitory mechanisms of selective attention for negative information are not a general feature of schizophrenia but appear to be selective to those with a depressed mood. The results highlight the need for further studies examining the exact nature of the affective dysfunction in schizophrenia and the cognitive processes supporting negative emotions.

Background. Cognitive models propose that auditory verbal hallucinations arise through defective self-monitoring and external attribution of inner speech. We used a paradigm that engages verbal self-monitoring to examine how deficits in this process are related to symptoms and diagnosis in patients with psychosis.

Method. We tested 45 patients with schizophrenia. Fifteen had current auditory hallucinations, 15 had a history of (but no current) auditory hallucinations, and 15 had delusions but neither current nor previous hallucinations. We also tested 10 patients with affective psychosis and current auditory hallucinations, and 20 healthy volunteers. Participants read single adjectives aloud while the source and the pitch of the on-line auditory verbal feedback was manipulated, then immediately identified the source of the speech they heard (‘self’/‘other’/‘unsure’).

Results. When reading aloud with distorted feedback of their own voice, patients with schizophrenia who had auditory hallucinations were more likely than controls to misidentify its source as ‘other’. Patients with delusions but no current hallucinations displayed a similar deficit, although there was a trend for this to be less marked. Patients with a history of hallucinations did not differ from controls. Patients with hallucinations in the context of an affective disorder made more unsure responses rather than misattributions.

Conclusions. Difficulty with source monitoring was related to the acute psychotic state rather than a predisposition to hallucinations, and was evident in patients with affective psychosis as well as schizophrenia. External misattribution of source may reflect an impairment in verbal self-monitoring and/or the appraisal of ambiguous sensory material.

Background. Formal thought disorder (FTD) has long been regarded as a key sign of schizophrenia but little is known about its origins or aetiology. One suggestion is that it is directly related to disordered language functioning; a second is that it is a reflection of poor neurocognitive functioning. A current model posits that it is related to a combination of executive dysfunction and impaired semantic processing.

Method. To examine these alternative ideas, a heterogeneous group of 30 patients, all carrying a diagnosis of schizophrenia, and 18 non-patient controls completed a series of neurocognitive and psycholinguistic tests, and a clinical review that, inter alia, permitted assessment of thought disorder (TD) using the Thought, Language and Communication Scale (TLC).

Results. Patients generally performed at a lower level on most components of the test battery, but there was little evidence of a relationship between TD and syntactic psycholinguistic function. However, schizophrenic patients manifesting higher levels of TD performed at a lower level on tests sensitive to executive dysfunction and semantic impairments.

Conclusions. The origins of TD seem more closely linked to deficits in executive functioning and semantic processing than to impairments in other language functions or general cognition.

Background. Prefrontal cortical dysfunctions, including disturbances in adaptive context-specific behavior, have been reported in neuropsychological and brain imaging studies of schizophrenia. Some data suggest that treatment with antipsychotic medications may ameliorate these deficits.

Method. We investigated antisaccade performance in 39 antipsychotic-naive, first-episode schizophrenia patients who were re-evaluated 6 weeks after treatment initiation. A group of matched healthy subjects were examined at similar time-points. Patients and healthy individuals available for longer-term testing were re-assessed 26 and 52 weeks after initial testing.

Results. Before treatment, patients showed elevated rates of response suppression errors and prolonged latencies of correct antisaccades. Increased rates of antisaccade errors were associated with faster response latencies during a separate, visually guided saccade task, but only prior to treatment. Throughout the 1-year follow-up, patients progressively improved in their ability to voluntarily suppress context-inappropriate behavior. Although treatment assignment was by clinician choice, results of exploratory analyses revealed that patients treated with risperidone progressively planned and initiated correct antisaccades more quickly than patients receiving haloperidol.

Conclusions. Deficits in the voluntary control of spatial attention are exaggerated during acute episodes of illness, but remain an enduring aspect of prefrontal dysfunction in schizophrenia even after treatment. During acute illness, speeded sensorimotor transformations may compound these deficits and contribute to the heightened distractibility associated with acute psychosis. Continued improvement in task performance throughout the 1-year follow-up suggests that partial normalization of prefrontal cognitive functions resulting from antipsychotic treatment may have a longer and more gradual time course than the reduction of acute psychotic symptoms.

Background. The ability to inhibit inappropriate or unwanted actions is a key element of executive control. The existence of executive function deficits in schizophrenia is consistent with frontal lobe theories of the disorder. Relatively few studies have examined response inhibition in schizophrenia, and none in adolescent patients with early-onset schizophrenia (EOS).

Methods. Twenty-one adolescents with the onset of clinically impairing psychosis before 19 years of age and 16 matched controls performed a stop-signal task to assess response inhibition. The patients with EOS were categorized as paranoid (n=10) and undifferentiated subtypes (n=11). The undifferentiated group had higher levels of negative symptomatology. Stop-signal reaction time (SSRT) and go-signal reaction time (Go-RT) were analysed with respect to hand of response.

Results. The undifferentiated early-onset patients had significantly longer SSRTs, indicative of poor response inhibition, for the left hand compared to the paranoid early-onset patients and control participants. No differences existed for inhibitory control with the right hand. The three groups did not differ in Go-RT.

Conclusions. Our results indicate a specific lateralized impairment of response inhibition in patients with undifferentiated, but not paranoid, EOS. These findings are consistent with reports of immature frontostriatal networks in EOS and implicate areas such as the pre-motor cortex and supplementary motor area (SMA) that are thought to play a role in both voluntary initiation and inhibition of movement.

Background. We explored the applicability of recently proposed research criteria for mild cognitive impairment (MCI) in a memory clinic and changes in case definition related to which memory tests are used and the status of general cognitive function in MCI.

Method. A total of 166 consecutive GP referrals to the Cambridge Memory Clinic underwent comprehensive neuropsychological and psychiatric evaluation.

Results. Of 166 cases, 42 were excluded (significant depression 8, established dementia 29 and other disorders 5). Of 124 non-demented, non-depressed patients, 72 fulfilled Petersen's criteria for amnestic MCI based upon verbal memory performance [the Rey Auditory Verbal Learning Test (RAVLT)] and 90 met criteria if performance on verbal and/or non-verbal memory tests [the Rey figure recall or the Paired Associates Learning test (PAL)] was considered. Of the 90 broadly defined MCI cases, only 25 had pure amnesia: other subtle semantic and/or attention deficits were typically present. A further 12 were classed as non-amnestic MCI and 22 as ‘worried well’.

Conclusions. Definition of MCI varies considerably dependent upon the tests used for case definition. The majority have other cognitive deficits despite normal performance on the Mini-mental State Examination (MMSE) and intact activities of daily living (ADL) and fit within multi-domain MCI. Pure amnesic MCI is rare.

Background. Although many studies have reported impairments of neurocognitive performance in patients with anorexia nervosa (AN), these have involved a wide range of assessment methods and some findings are inconsistent.

Method. Twenty-five female in-patients with a DSM-IV diagnosis of AN, identified from three units specializing in the treatment of eating disorders, volunteered for the study. Twenty-five non-clinical control subjects were recruited, matched for age, gender and estimated IQ. Subjects were assessed with a range of computer-administered neurocognitive tasks from the Cambridge Neuropsychological Test Automated Battery (CANTAB), which has been validated in many studies of neuropsychiatric disorders.

Results. The patient group showed significant but moderate impairments (i.e. less than one standard deviation below the mean performance of the control group) on tests of spatial recognition memory, a planning task and rapid visual information processing, while a subgroup of patients (n=14) showed greater degrees of impairments on at least one of these tests. The degrees of impairments did not correlate with body mass index (BMI). No impairments were observed on tests of spatial span, pattern recognition memory, spatial working memory, matching-to-sample, paired associates learning and set-shifting.

Conclusions. The findings, in relation to a mean BMI of 15·3, are compatible with, in general, subtle impairments in neurocognition in AN. However, in those patients with relatively severe degrees of impairments, these may have adverse effects on complex tasks of social and occupational functioning. Further research is needed on the nature of relevant causal mechanisms, including the effects of potentially confounding variables.

Background. In view of the potential utility of personality-based groupings in eating disorders (EDs), and the lack of studies using this approach in large samples of individuals with anorexia nervosa (AN), this study set out to examine (i) the nature of personality-based clusters of women with lifetime AN and (ii) if these clusters are associated with either clinical symptoms or aetiological variables.

Method. The self-report Dimensional Assessment of Personality Pathology (DAPP) was completed by 153 women with a lifetime diagnosis of DSM-IV AN. A cluster analysis was used to identify personality-based subgroups. Clusters were then compared on clinical and aetiological variables.

Results. Three personality-based clusters were identified, defined by broad, avoidant and compulsive types of personality pathology. Dimensions of low dissocial behaviour, high inhibition and high compulsivity were common to all clusters, while dimensions related to emotional dysregulation appeared more heterogeneous. Clinical symptoms were not related to personality profile with the exception of a trend towards more fasting behaviour in the broad group. The compulsive cluster with the narrowest range of extreme personality traits reported the highest familial risk of eating pathology.

Conclusions. The three clusters identified in our AN sample were similar to those previously identified in broader eating disordered samples. Personality-based clusters did not correspond overall to clinical symptoms but aetiological differences supported their validity. Broader personality pathology indicative of emotional dysregulation, problems with identity and relationships, in addition to core traits, may increase vulnerability to AN in those with less familial risk.

Objective. Eating disorders are more common in females than in males. Gender differences may be due to organizational (i.e. prenatal) and activational (i.e. post-natal) gonadal hormone effects that influence sex differences in behavior. This preliminary set of studies examined these effects by investigating relationships between eating disorder symptoms, prenatal testosterone exposure, and adult levels of estrogen in women.

Method. We examined organizational associations by investigating relationships between disordered eating and finger-length ratios, which are known to be somatic markers of prenatal testosterone exposure. Participants included 113 adult female twins drawn from the community. Disordered eating was assessed with the total score from the Minnesota Eating Behavior Survey (MEBS). Finger lengths were hand scored using a ruler and photocopies of both hands. We also investigated activational influences by examining associations between circulating levels of estradiol and disordered eating symptoms. Two independent samples of adult females (n's=24 and 25) drawn from the community were used for this study. Disordered eating was again assessed with the MEBS total score, while saliva samples were used for assessing estradiol.

Results. Positive associations were found between disordered eating and both finger-length ratios and circulating estradiol levels.

Conclusions. Findings suggest that lower levels of prenatal testosterone exposure and higher adult levels of estradiol are associated with increased eating disorder symptoms. We hypothesize that the relatively low level of testosterone before birth in females permits their brains to respond to estrogens at puberty, when the hormones activate the genes contributing to disordered eating in vulnerable girls.

Background. Although a correlation between the central dopaminergic system and intelligence may exist, the results from imaging studies remain inconclusive. The aim of this study was to explore the relationship between striatal dopamine D2/D3 receptor availability and verbal intelligence quotient (VIQ) using single photon emission computed tomography (SPECT).

Method. Striatal D2/D3 receptor availability of 64 healthy subjects was determined with the [123I]iodobenzamide ([123I]IBZM) ligand. Intelligence quotients (IQs) of the subjects were measured by the Wechsler Adult Intelligence Scale – Revised (WAIS-R).

Results. In addition to age, left striatal D2/D3 receptor availability correlated positively with VIQ. In females, left striatal D2/D3 receptor availability was the only variable that correlated significantly with the similarities subtest of VIQ.

Conclusions. There is a relationship between left striatal D2/D3 receptor availability and verbal intelligence, which varies, predominantly in males.

Background. Psychotherapy's equivalence paradox is that treatments have equivalently positive outcomes despite non-equivalent theories and techniques. We compared the outcomes of contrasting approaches practised in routine care.

Method. Patients (n=1309) who received cognitive-behavioural therapy (CBT), person-centred therapy (PCT) and psychodynamic therapy (PDT) at one of 58 National Health Service (NHS) primary and secondary care sites in the UK during a 3-year period completed the Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM) at the beginning and end of their treatment. Therapists indicated which treatment approaches were used on an End of Therapy form. We compared outcomes of six groups: three treated with CBT, PCT or PDT only, and three treated with one of these plus one additional approach (e.g. integrative, supportive, art), designated CBT+1, PCT+1 or PDT+1 respectively.

Results. All six groups averaged marked improvement (pre–post effect size=1·36). Treatment approach and degree of purity (‘only’ vs. ‘+1’) each accounted for statistically significant but comparatively tiny proportions of the variance in CORE-OM scores (respectively 1% and 0·5% as much as pre–post change). Distributions of change scores were largely overlapping.

Conclusions. Results for these three treatment approaches as practised routinely across a range of NHS settings were generally consistent with previous findings that theoretically different approaches tend to have equivalent outcomes. Caution is warranted because of limited treatment specification, non-random assignment, lack of a control group, missing data and other issues.