Is Ginkgo biloba a cognitive enhancer in healthy individuals? A meta-analysis.

OBJECTIVE: We conducted a meta-analysis to examine whether Ginkgo biloba (G. biloba) enhances cognitive function in healthy individuals. METHODS: Scopus, Medline, Google Scholar databases and recent qualitative reviews were searched for studies examining the effects of G. biloba on cognitive function in healthy individuals. We identified randomised controlled trials containing data on memory (K = 13), executive function (K = 7) and attention (K = 8) from which effect sizes could be derived. The analyses provided measures of memory, executive function and attention in 1132, 534 and 910 participants, respectively. RESULTS: Effect sizes were non-significant and close to zero for memory (d = -0.04: 95%CI -0.17 to 0.07), executive function (d = -0.05: 95%CI -0.17 to 0.05) and attention (d = -0.08: 95%CI -0.21 to 0.02). Meta-regressions showed that effect sizes were not related to participant age, duration of the trial, daily dose, total dose or sample size. CONCLUSIONS: We report that G. biloba had no ascertainable positive effects on a range of targeted cognitive functions in healthy individuals.

Cognitive Behavioural Therapy for schizophrenia - outcomes for functioning, distress and quality of life: a meta-analysis.

BACKGROUND: The effect of cognitive behavioural therapy for psychosis (CBTp) on the core symptoms of schizophrenia has proven contentious, with current meta-analyses finding at most only small effects. However, it has been suggested that the effects of CBTp in areas other than psychotic symptoms are at least as important and potentially benefit from the intervention. METHOD: We meta-analysed RCTs investigating the effectiveness of CBTp for functioning, distress and quality of life in individuals diagnosed with schizophrenia and related disorders. Data from 36 randomised controlled trials (RCTs) met our inclusion criteria- 27 assessing functioning (1579 participants); 8 for distress (465 participants); and 10 for quality of life (592 participants). RESULTS: The pooled effect size for functioning was small but significant for the end-of-trial (0.25: 95% CI: 0.14 to 0.33); however, this became non-significant at follow-up (0.10 [95%CI -0.07 to 0.26]). Although a small benefit of CBT was evident for reducing distress (0.37: 95%CI 0.05 to 0.69), this became nonsignificant when adjusted for possible publication bias (0.18: 95%CI -0.12 to 0.48). Finally, CBTp showed no benefit for improving quality of life (0.04: 95% CI: -0.12 to 0.19). CONCLUSIONS: CBTp has a small therapeutic effect on functioning at end-of-trial, although this benefit is not evident at follow-up. Although CBTp produced a small benefit on distress, this was subject to possible publication bias and became nonsignificant when adjusted. We found no evidence that CBTp increases quality of life post-intervention.

Greater cognitive deterioration in women than men with Alzheimer's disease: a meta analysis.

Studies reporting on the cognitive abilities of men and women with Alzheimer's disease (AD) are surprisingly rare. We carried out a meta-analysis of neurocognitive data from 15 studies (n = 828 men; 1,238 women), which revealed a consistent male advantage on verbal and visuospatial tasks and tests of episodic and semantic memory. Moderator regression analyses showed that age, education level, and dementia severity did not significantly predict the male advantage. Reasons posited for this advantage include a reduction of estrogen in postmenopausal women, sex differences in AD pathology, and greater cognitive reserve in men.

Name relearning in elderly patients with schizophrenia: episodic and temporary, not semantic and permanent.

INTRODUCTION: Recent reports of lexical-semantic deficits in patients with schizophrenia (Laws, Al-Uzri, & Mortimer, 2000; Laws, McKenna, & Kondel, 1998) suggest that younger patients have problems accessing intact memories and older patients show apparent "loss" of the lexical-semantic memory representations themselves. METHODS: Picture naming for everyday items was examined in a unique series of elderly patients with schizophrenia (n = 10) with a mean illness duration of 45.5 years; and compared with that in patients with probable Alzheimer's disease (n = 18) and elderly healthy controls (n = 27). Naming consistency across time was used as an indicator of whether the schizophrenic patients had difficulty accessing representations or a loss of the representations themselves. Finally, we examined the ability of the schizophrenic patients to relearn the names of unnamed items across four weekly retraining sessions and to retain them at a one month follow-up. RESULTS: The elderly schizophrenic patients were as anomic as patients with probable Alzheimer's disease. Consistency analysis revealed that the patients had storage deficits. Analysis of patient error types was consistent with a semantic deficit. Finally, the schizophrenic patients showed significant improvement with relearning, but this was not maintained at follow-up. CONCLUSIONS: Elderly patients with schizophrenia show a profound and stable anomia. Although name relearning induced some significant gains in naming, these were short-term and reflect episodic rather than semantic reinstatement of representations. Implications for cognitive remediation are discussed.

What happens to semantic memory when formal thought disorder remits? Revisiting a case study.

INTRODUCTION: Laws, Kondel, and McKenna (1999) previously reported a case study analysis of a schizophrenic patient (TC) with severe formal thought disorder (FTD). Examining consistency across item and modality of input, Laws et al. documented an impairment of access to semantic knowledge in TC. METHOD: Following substantial improvement in his FTD, we readministered the same extensive battery of neuropsychological tests tapping semantic memory functioning. RESULTS: Whilst TC's naming remained relatively good, it also became more consistent across both time and modality. Tasks tapping language comprehension and understanding of semantic association revealed some significant improvements. Nevertheless, TC showed a residual propensity to verify false information. CONCLUSION: Improvement in FTD in schizophrenia was accompanied by a better and more stable semantic memory performance in TC. The findings are consistent with, and expand upon the original suggestion that thought disorder reflects disorganised access to semantic memory.

Prospective memory and executive function in schizophrenia.

Experimental studies of normal subjects have shown that the intention to perform an action speeds word recognition for items related to that intention (Goschke & Kuhl, 1993). This phenomenon--the intention superiority effect (ISE)--is thought to be mediated by frontal executive functions. Since schizophrenia is characteristically associated with forms of frontal-executive dysfunction, an impaired ISE might be expected in this patient group. A script-learning paradigm was used to investigate the ISE in 10 schizophrenics who do show evidence of executive dysfunction and in 10 who do not. As predicted, only the former showed an ISE; however, all schizophrenics showed an ISE to words semantically related to the intention. It seems that the ability to form specific intentions is impaired only in schizophrenics with executive dysfunction; however, they retain the ability to form more generalized intentions.

Intellectual differences between schizophrenic patients and normal controls across the adult lifespan.

A debate persists about whether IQ declines during the duration of schizophrenia or whether an early deficit remains static across the lifespan. To examine this, we measured estimated current IQ (Quick Test Revised: QTR) and estimated premorbid IQ (National Adult Reading Test: NART) in schizophrenic patients (n=110) and matched healthy controls (n=71) across a wide age range (20-88). Age correlated negatively with NART and QTR IQ for schizophrenic patients, but not for controls. A subset of 23 schizophrenic patients was also retested on the NART after 4 years to determine NART stability and they showed no significant change. We propose that the lower NART IQ in older patients reflects a lower 'starting point' and that this may be related to lower educational opportunities in older patients.