Objective To explore the association between migraine and risk of ischaemic stroke. Design Systematic review and meta-analysis. Data sources Observational studies published between 1966 and June 2004 (identified through Medline and Embase) that examined the association between migraine and risk of ischaemic stroke. Results 14 studies (11 case-control studies and 3 cohort studies) were identified. These studies suggest that the risk of stroke is increased in people with migraine (relative risk 2.16, 95% confidence interval 1.89 to 2.48). This increase in risk was consistent in people who had migraine with aura (relative risk 2.27, 1.61 to 3.19) and migraine without aura (relative risk 1.83, 1.06 to 3.15), as well as in those taking oral contraceptives (relative risk 8.72, 5.05 to 15.05). Conclusions Data from observational studies suggest that migraine may be a risk factor in developing stroke. More studies are needed to explore the mechanism of this potential association. In addition, the risk of migraine among users of oral contraceptives must be further investigated.

Purpose: To determine whether intake of tomato products reduces the risk of prostate cancer using a meta-analysis. Methods: We systematically searched MEDLINE and EMBASE and contacted authors to identify potential studies. Log relative risks (RRs) were weighed by the inverse of their variances to obtain a pooled estimate with its 95% confidence interval (CI). Logistic regression and Poisson regression analyses were used to determine the effect produced by a daily intake of one serving of tomato product. Results: Eleven case-control studies and 10 cohort studies or nested case-control studies presented data on the use of tomato, tomato products, or lycopene and met our inclusion criteria. Compared with nonfrequent users of tomato products (1st quartile of intake), the RR of prostate cancer among consumers of high amounts of raw tomato (5th quintile of intake) was 0.89 (95% CI 0.80–1.00). For high intake of cooked tomato products, this RR was 0.81 (95% CI 0.71–0.92). The RR of prostate cancer related to an intake of one serving/day of raw tomato (200 g) was 0.97 (95% CI 0.85–1.10) for the case-control studies and 0.78 (95% CI 0.66–0.92) for cohort studies. Conclusion: Our results show that tomato products may play a role in the prevention of prostate cancer. However, this effect is modest and restricted to high amounts of tomato intake. Further research is needed to determine the type and quantity of tomato products with respect to their role in preventing prostate cancer.

Considerable controversy exists about the role of education in the risk of dementia. Individual studies have not been conclusive so far. To examine the hypothesis that lower education is associated with a higher risk of dementia, we carried out a meta-analysis. Observational studies published as of October 2005 that examined the association between education and risk of dementia were systematically reviewed. Relative risks (RRs) and odds ratios were extracted from cohort and case-control studies. We first compared the risk of dementia in subjects with high level of education with the risk of dementia in those with low educational level. In a subsequent analysis, we compared the risk of persons with high education with the risk of subjects with education level other than high (medium, low). We weighted log RRs for cohort studies or odds ratios by the inverse of their variances. Nineteen studies were included in our meta-analysis (13 cohort and 6 case-control studies). RRs for low versus high education level were: Alzheimer’s disease (AD) 1.80 (95% CI: 1.43–2.27); non-AD dementias, 1.32 (95% CI: 0.92–1.88), and all dementias 1.59 (95% CI: 1.26–2.01). For low and medium versus high education level, the RRs were: AD 1.44 (95% CI: 1.24–1.67); non-AD 1.23 (95% CI: 0.94–1.61), and all dementias 1.33 (95% CI: 1.15–1.54). These results confirm that low education may be a risk factor for dementia, especially for AD.