A cluster randomised controlled trial was used to investigate the effectiveness of training staff in 13 London community mental health teams (CMHTs) to deliver substance misuse interventions to patients with psychosis and comorbid substance misuse (‘dual diagnosis’). The primary hypotheses, which were that experimental group patients would spend fewer days in hospital over 18 months of follow-up and show reduced alcohol and drug consumption, were not confirmed, although confidence intervals were wide for some outcomes. Current UK policy guidance advocates training CMHT professionals to deliver dual diagnosis interventions, but the effectiveness of this strategy has not so far been demonstrated.

Caudate nuclei are smaller in drug-naive people with schizophrenia but larger in antipsychotic-treated patients. In this magnetic resonance imaging study we found volume reduction of right and left caudate by 8.9 and 8.1% respectively in 50 offspring without psychosis of patients with schizophrenia compared with 53 age- and gender-matched controls, providing new evidence that caudate volume reduction may be a trait-related abnormality in schizophrenia.

Schizophrenia is often associated with difficulties in distinguishing between actions of self and of others. This could reflect dysfunction of the mirror neuron system which directly matches observed and executed actions. We studied 11 people with schizophrenia and their co-twins without manifest disease, using stimulus-induced changes in the magnetoencephalographic $20 Hz rhythm as an index of activation in the motor cortex part of the mirror neuron system. During action observation and execution, motor cortex reaction was weaker in those with schizophrenia than in their co-twins, suggesting a disease-related dysfunction of motor cognition.

A tendency to extract spurious, message-like meaning from meaningless noise was assessed as a risk factor leading to shizophrenia-spectrum disorders by assessing word length of speech illusions elicited by multispeaker babble in 43 people with prodromal symptoms. These individuals were randomised to olanzapine v. placebo groups during year 1 followed by no pharmacological treatment for those with no disorder conversion during year 2. A time-dependent Cox regression analysis of conversion to schizophrenia-spectrum disorder revealed a significant interaction between condition (olanzapine v. no drug) and length of speech illusion, with the latter strongly predicting subsequent conversion during medication-free intervals but not during olanzapine treatment.

Studies of drug treatments are more likely to report favourable outcomes when they are funded by the pharmaceutical industry. We compared drug trials reported in three major psychiatric journals to investigate these influences. Independent studies were more likely to report negative findings than industry-funded studies. However, the involvement of a drug company employee had a much greater effect on study outcome than financial sponsorship alone.

We tested a phenomenological hypothesis about theoretical and practical rationality in people with schizophrenia. This hypothesis states that in schizophrenia there is an enhancement of theoretical rationality Our case–control experiment supported this hypothesis. Philosophical models of rationality that prioritise theoretical over practical rationality may thereby apply more in schizophrenic than in healthy states. The study is an example of how experimental psychopathology can illuminate areas of philosophical dispute that are difficult to settle by thought alone.

We assessed premorbid functioning during childhood and adolescence in 50 people with schizophrenia from multiply affected families, 39 of their unaffected siblings, 69 people with schizophrenia with no family history of psychosis, 67 of their unaffected siblings and 83 controls. People with schizophrenia had poorer premorbid social and academic adjustment and exhibited a decline between childhood and adolescence compared with controls. Unaffected siblings from multiply affected families also had poor academic functioning in adolescence, with a decline between childhood and adolescence. This may represent a familial (presumed genetic) effect.

Insight, psychopathology and functioning are related in schizophrenia, but it is unclear whether insight relates independently to functioning after controlling for psychopathology. Equally, any such relationship may vary culturally. We investigated the relationship between insight, psychopathology and functioning in 60 patients with schizophrenia in Mzuzu, a town in Malawi. After controlling for psychopathology, functioning was associated with the ‘symptom relabelling’ dimension of insight (P=0.01). This preliminary finding suggests that symptom-focused psychoeducation might be appropriate for African patients with schizophrenia.

There is conflicting evidence regarding the effect of depression during pregnancy on birth weight. We used data from the Avon Longitudinal Study of Parents and Children to investigate whether depressive symptoms during pregnancy in 10 967 women led to low birth weight at term in their offspring. Those with a high depressive symptom score during pregnancy were more likely to have babies of low birth weight (95% CI 1.16–2.40, P < 0.01), but this attenuated after adjustment for confounders (OR = 1.29, 95% CI 0.87–1.91, P = 0.210). Hence there is little evidence of an independent association between depressive symptoms during pregnancy and birth weight.