Cognitive-behavioural therapy for the symptoms of schizophrenia: systematic review and meta-analysis with examination of potential bias.

BACKGROUND: Cognitive-behavioural therapy (CBT) is considered to be effective for the symptoms of schizophrenia. However, this view is based mainly on meta-analysis, whose findings can be influenced by failure to consider sources of bias. AIMS: To conduct a systematic review and meta-analysis of the effectiveness of CBT for schizophrenic symptoms that includes an examination of potential sources of bias. METHOD: Data were pooled from randomised trials providing end-of-study data on overall, positive and negative symptoms. The moderating effects of randomisation, masking of outcome assessments, incompleteness of outcome data and use of a control intervention were examined. Publication bias was also investigated. RESULTS: Pooled effect sizes were -0.33 (95% CI -0.47 to -0.19) in 34 studies of overall symptoms, -0.25 (95% CI -0.37 to -0.13) in 33 studies of positive symptoms and -0.13 (95% CI -0.25 to -0.01) in 34 studies of negative symptoms. Masking significantly moderated effect size in the meta-analyses of overall symptoms (effect sizes -0.62 (95% CI -0.88 to -0.35) v. -0.15 (95% CI -0.27 to -0.03), P = 0.001) and positive symptoms (effect sizes -0.57 (95% CI -0.76 to -0.39) v. -0.08 (95% CI -0.18 to 0.03), P<0.001). Use of a control intervention did not moderate effect size in any of the analyses. There was no consistent evidence of publication bias across different analyses. CONCLUSIONS: Cognitive-behavioural therapy has a therapeutic effect on schizophrenic symptoms in the 'small' range. This reduces further when sources of bias, particularly masking, are controlled for.

A critique of narrative reviews of the evidence-base for ECT in depression.

There has been recent debate regarding the efficacy of electroconvulsive therapy in the treatment of depression. This has been based on narrative reviews that contradict existing systematic reviews and meta-analyses. In this special article, we highlight the mistakes that occur when interpreting evidence using narrative reviews, as opposed to conventional systematic reviews and meta-analyses.

Cognitive behavioural therapy for major psychiatric disorder: does it really work? A meta-analytical review of well-controlled trials.

BACKGROUND: Although cognitive behavioural therapy (CBT) is claimed to be effective in schizophrenia, major depression and bipolar disorder, there have been negative findings in well-conducted studies and meta-analyses have not fully considered the potential influence of blindness or the use of control interventions. METHOD: We pooled data from published trials of CBT in schizophrenia, major depression and bipolar disorder that used controls for non-specific effects of intervention. Trials of effectiveness against relapse were also pooled, including those that compared CBT to treatment as usual (TAU). Blinding was examined as a moderating factor. RESULTS: CBT was not effective in reducing symptoms in schizophrenia or in preventing relapse. CBT was effective in reducing symptoms in major depression, although the effect size was small, and in reducing relapse. CBT was ineffective in reducing relapse in bipolar disorder. CONCLUSIONS: CBT is no better than non-specific control interventions in the treatment of schizophrenia and does not reduce relapse rates. It is effective in major depression but the size of the effect is small in treatment studies. On present evidence CBT is not an effective treatment strategy for prevention of relapse in bipolar disorder.

The neuropsychology of the schizo-obsessive subtype of schizophrenia: a new analysis.

BACKGROUND: Interest in the neuro-cognitive profile of patients with schizophrenia and co-morbid obsessive compulsive disorder (schizo-OCD) is rising in response to reports of high co-morbidity rates. Whereas schizophrenia has been associated with global impairment in a wide range of neuro-cognitive domains, OCD is associated with specific deficits featuring impaired performance on tasks of motor and cognitive inhibition involving frontostriatal neuro-circuitry. METHOD: We compared cognitive function using the CANTAB battery in patients with schizo-OCD (n=12) and a schizophrenia group without OCD symptoms (n=16). The groups were matched for IQ, gender, age, medication, and duration of illness. RESULTS: The schizo-OCD patients made significantly more errors on a task of attentional set-shifting (ID-ED set-shift task). By contrast, no significant differences emerged on the Stockings of Cambridge task, the Cambridge Gamble Task or the Affective Go/NoGo tasks. No correlation emerged between ID-ED performance and severity of schizophrenia, OCD or depressive symptoms, consistent with neurocognitive impairment holding trait rather than state-marker status. Schizo-obsessives also exhibited a trend toward more motor tics emphasizing a neurological contribution to the disorder.ConclusionOur findings reveal a more severe attentional set-shifting deficit and neurological abnormality that may be fundamental to the neuro-cognitive profile of schizo-OCD. The clinical implications of these impairments merit further exploration in larger studies.

Facial emotion processing in schizophrenia: a non-specific neuropsychological deficit?

BACKGROUND: Identification of facial emotions has been found to be impaired in schizophrenia but there are uncertainties about the neuropsychological specificity of the finding. METHOD: Twenty-two patients with schizophrenia and 20 healthy controls were given tests requiring identification of facial emotion, judgement of the intensity of emotional expressions without identification, familiar face recognition and the Benton Facial Recognition Test (BFRT). The schizophrenia patients were selected to be relatively intellectually preserved. RESULTS: The patients with schizophrenia showed no deficit in identifying facial emotion, although they were slower than the controls. They were, however, impaired on judging the intensity of emotional expression without identification. They showed impairment in recognizing familiar faces but not on the BFRT. CONCLUSIONS: When steps are taken to reduce the effects of general intellectual impairment, there is no deficit in identifying facial emotions in schizophrenia. There may, however, be a deficit in judging emotional intensity. The impairment found in naming familiar faces is consistent with other evidence of semantic memory impairment in the disorder.

[A theoretical review of category-specific impairment, its entity and the methodological problems associated with its study]. / Revisión teórica del deterioro categorial, su entidad y los problemas metodológicos asociados a su estudio.

INTRODUCTION: Studies on category-specific claim to provide insights on structure and organization of semantic information. This type of phenomenon consists of the selective impairment of the information on a domain, for instance, living things (animals) but the sparing of nonliving things (tools), or vice versa. Despite the large number of studies purportedly documenting double dissociations between both domains, the lack of theoretical debate on how to empirically define such dissociations is unclear, e.g. how they should be evaluated and reported. DEVELOPMENT: In this work, a review of literature on category-specific and the explanatory models is showed. A critical methodological is done, on the basis of three findings: 1) lack of normal control groups in the majority of case studies; 2) the questionable utilization of double dissociations; and 3) the presence of problems due to a 'ceiling effect' in most group studies of Alzheimer disease patients. CONCLUSIONS: It is claimed that while domain specificity may be a legitimate phenomenon, the critical review of literature do not provide a strong empirical foundation for the domain fractionations claimed in this literature.

A normal' category-specific advantage for naming living things.

'Artefactual' accounts of category-specific disorders for living things have highlighted that compared to nonliving things, living things have lower name frequency, lower concept familiarity and greater visual complexity and greater within-category structural similarity or 'visual crowding' [7]. These hypotheses imply that deficits for living things are an exaggeration of some 'normal tendency'. Contrary to these notions, we found that normal subjects were consistently worse at naming nonliving than living things in a speeded presentation paradigm. Moreover, their naming was not predicted by concept familiarity, name frequency or visual complexity; however, a novel measure of visual familiarity (i.e. for the appearance of things) did significantly predict naming. We propose that under speeded conditions, normal subjects find nonliving things harder to name because their representations are less visually predictable than for living things (i.e. nonliving things show greater within-item structural variability). Finally, because nonliving things have multiple representations in the real world, this may lower the probability of finding impaired naming and recognition in this category.

On the distinction between access and store disorders in schizophrenia: a question of deficit severity?

This study documents a severe face naming impairment in schizophrenic patients. A series of twelve patients was examined further to determine whether this deficit conformed to either an access or store disorder as described originally by Warrington and Shallice. This analysis of consistency across time, effects of cueing and familiarity effects revealed heterogeneous performance patterns; pointing to access disorders in some patients and store disorders in others. However, the difference between access-like and store-like patterns of performance was strongly correlated with quantitative differences in patient deficit-severity. Hence, the notion of dichotomous access and store disorders, in schizophrenic patients, may be deceptive; with the naming performance of schizophrenics varying according to the extent of their stored knowledge, rather than any qualitative differences between patients. These findings have implications for our understanding of: cognitive deficits in both schizophrenic and neurological patients; the relationship between psychotic and neurological disorders and perhaps for the underlying neurophysiological dysfunction.

Lexical knowledge degradation in schizophrenia.

This study documents a severe picture naming impairment in a series of 22 chronically hospitalised schizophrenics. The pattern and level of naming impairment were comparable in degree and type to that seen neurological patients with left hemisphere lesions. This deficit was further examined to determine whether it conformed to a disorder affecting access to the lexical representations or some degradation of the stored representations themselves. Patient naming was examined twice (18months apart) for evidence of consistency and for word frequency effects. The pattern of individual patient performance on these criteria showed that the majority had storage disorders; access disorders alone occurred in only a small minority of patients. A subset of 11 of the same patients that were tested on three occasions (across 30months) showed the same pattern but further indicated that when access problems are present, they reflect difficulty with deliberate, rather than automatic, access to the lexicon.

Gender affects naming latencies for living and nonliving things: implications for familiarity.

Recent studies indicate the presence of a gender-by-category interaction in the naming abilities of both Alzheimer's patients and normal subjects (Laiacona, Barbarotto and Capitani, 1998; McKenna and Parry, 1994). In particular, males appear to be better than females at naming nonliving things and females better at naming living things. Similarly, in a recent study of semantic fluency, males retrieved more names of tools than females and females more names of fruit than males (Capitani, Laiacona and Barbarotto, 1999). Such findings have important implications for our understanding of category-specific disorders. The current study examined the naming latencies of normal subjects to pictures of living and nonliving things. We confirm a gender-by category interaction across both subject and item, with females being slower than males to name nonliving things and males slower to name living things. This finding could not be explained by differential difficulty of items or differences in gender-based familiarity ratings.

Object recognition without knowledge of object orientation.

Several theories have been proposed to explain our ability to recognise objects from a number of viewpoints. Orientation-dependent accounts emphasize the position of the object relative to the viewer, while orientation-independent accounts (e.g. Marr) rely on descriptions of an object's component parts relative to its principal axis of elongation. An opportunity to compare the merit of these theories has arisen in a patient (L.G.) who had a rare neuropsychological sign in which knowledge of the canonical upright of object drawings was profoundly disrupted. Such orientation errors were evident in her drawings from memory and to copy, and in an orientation-matching task. In a critical experiment she showed a deficit in providing the canonical upright of individual object drawings that was independent of any difficulty in object recognition. The implications of these data for theories of object recognition are discussed.

Category-specific naming errors in normal subjects: the influence of evolution and experience.

The importance of "artifactual" variables (such as conceptual familiarity) have been highlighted in current accounts of category-specific disorders for living things (e.g., Funnell & Sheridan, 1992). The difficulties experienced by patients are essentially viewed as an exaggeration of normal processes and the implication is that normal subjects should also have greater difficulty naming living items (because they have lower conceptual familiarity than nonliving things). The current study examined normal subjects' ability to name pictures of artifact-matched sets of living and nonliving things in a naming-to-deadline paradigm. Contrary to the prediction, normal subjects made more nonliving naming errors. Furthermore, female subjects made more nonliving-thing errors than male subjects. These findings could not be reduced to differences in either category-based or gender-based familiarity ratings. Rather, it is proposed that an elaborated domain-specific evolutionary model parsimoniously explains both the greater incidence of living thing deficits in patients and the better performance of normal subjects with living things.

Semantic priming in schizophrenia: systematic review and meta-analysis.

BACKGROUND: Increased semantic priming is an influential theory of thought disorder in schizophrenia. However, studies to date have had conflicting findings. AIMS: To investigate semantic memory in patients with schizophrenia with and without thought disorder. METHOD: Data were pooled from 36 studies comparing patients with schizophrenia and normal controls in semantic priming tasks. Data from 18 studies comparing patients with thought disorder with normal controls, and 13 studies comparing patients with and without thought disorder were also pooled. RESULTS: There was no support for altered semantic priming in schizophrenia as a whole. Increased semantic priming in patients with thought disorder was supported, but this was significant only in comparison with normal controls and not in comparison with patients without thought disorder. Stimulus onset asynchrony (SOA) and general slowing of reaction time moderated the effect size for priming in patients with thought disorder. CONCLUSIONS: Meta-analysis provides qualified support for increased semantic priming as a psychological abnormality underlying thought disorder. However, the possibility that the effect is an artefact of general slowing of reaction time in schizophrenia has not been excluded.