Low atmospheric pressure and high relative air humidity are associated with an increased risk for epileptic seizures, whereas high ambient temperatures seem to decrease seizure risk. Weather-dependent seizure risk may be accentuated in patients with less severe epilepsy. Our results require further replication across different climate regions and cohorts before reliable clinical recommendations can be made.

Observational studies focusing on absolute meteorological values suggest an association between meteorological parameters and stroke risk but these results are inconsistent and conflicting. Since changes in weather can provoke atrial fibrillation, we examined the association between rapid weather changes and stroke risk in 1694 patients with determinable onset of stroke symptoms in a case-crossover study in central Germany. Days one to three before stroke onset were classified as hazard periods and day seven as the respective control period. Risk of ischemic stroke in relation to 24 h differences in mean ambient temperature, relative humidity and atmospheric pressure was determined. The association between temperature and stroke risk appears to be close to linear with an increase in stroke risk of 11 % (odds ratio 1.11, 95 % confidence interval 1.01-1.22) for each 2.9 °C temperature decrease over 24 h. In individuals with a higher cardiovascular risk, stroke risk increased by 30 % (1.30, 1.06-1.61). Risk for cardioembolic strokes increased by 26 % (1.26, 1.06-1.50). Rapid positive or negative changes in relative humidity (>5 %) and atmospheric pressure (>10 hPa) increased stroke risk by a maximum of 30 % (1.30, 1.02-1.66) and 63 % (1.63, 1.10-2.42). In individuals with a higher cardiovascular risk, rapid changes in atmospheric pressure were associated with a four-times higher stroke risk (4.56, 1.26-16.43). Our results suggest that rapid decreases in ambient temperature and rapid changes in relative humidity and atmospheric pressure increase stroke risk under temperate climate conditions. Individuals with a high cardiovascular risk profile seem to be at greater risk.

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Aims High concentrations of air pollutants are associated with increased risk for myocardial infarction. The European Union has defined statutory limits for air pollutants based on upper absolute concentrations. We evaluated the association between rapid changes in air pollutants and the risk of myocardial infarction independently of absolute concentrations. Methods and results Using a hospital-based case-crossover study, effects of 24h changes of nitrogen oxides (NO), particulate matter (PM), and ozone on the risk of myocardial infarction was assessed in 693 patients. In the overall population, increases of NO of more than 20 µg/m within 24 h were associated with an increase in the risk of myocardial infarction by up to 121% (odds ratio (OR) 2.21, 95% confidence interval (CI) 1.19-4.08). Comparably, rapid increases of NO of more than 8 µg/m tended to increase myocardial infarction risk by 73% (OR 1.73, 95% CI 0.91-3.28) while myocardial infarction risk decreased by 60% after a decrease of NO concentration of more than 8 µg/m (OR 0.4, 95% CI 0.21-0.77), suggesting a close-to-linear association. While results for ozone concentrations were ambiguous, rapid change in PM was not associated with myocardial infarction risk. Conclusion Dynamics and extent of increase in nitrogen oxide concentrations may be an independent risk factor for myocardial infarction. As there are currently no European Union statutory limits reflecting this dynamic variation of air pollutants on a daily basis, the results urgently call for confirming studies in different geographical regions to verify the observations.

Prenatal maternal stress (PMS) programs dysregulation of the hypothalamus-pituitary-adrenal axis (HPAA) in postnatal life, though time periods vulnerable to PMS, are still unclear. We evaluated in pregnant sheep the effect of PMS during early gestation [30-100 days of gestation (dGA); term is 150 dGA] or late gestation (100-120 dGA) on development of fetal HPAA function. We compared the effects of endogenous cortisol with synthetic glucocorticoid (GC) exposure, as used clinically to enhance fetal lung maturation. Pregnant sheep were exposed to repeated isolation stress twice per week for 3 h in a separate box with no visual, tactile, or auditory contact with their flock-mates either during early (n = 7) or late (n = 7) gestation. Additional groups received two courses of betamethasone (BM; n = 7; 2 × 110 μg kg(- 1) body weight, 24 h apart) during late gestation (106/107 and 112/113 dGA, n = 7) or acted as controls (n = 7). Fetal cortisol responses to hypotensive challenge, a physiological fetal stressor, were measured at 112 and 129 dGA, i.e. before and during maturation of the HPAA. Hypotension was induced by fetal infusion of sodium nitroprusside, a potent vasodilator. At 112 dGA, neither PMS nor BM altered fetal cortisol responses. PMS, during early or late gestation, and BM treatment increased fetal cortisol responses at 129 dGA with the greatest increase achieved in stressed early pregnant sheep. Thus, development of the HPAA is vulnerable to inappropriate levels of GCs during long periods of fetal life, whereas early gestation is most vulnerable to PMS.