BMJ No 7031 Volume 312. This Week in BMJ

Thunderstorm associated asthma is thought to be an epidemic illness precipitated by environmental conditions. Although localised outbreaks have been reported, the asthma epidemic after a thunderstorm in June 1994 occurred in many areas of England and is thought to have been substantially larger than previous outbreaks. Wallis et al (p 601) investigated the phenomenon in 12 accident and emergency departments in London. They found that the epidemic began abruptly after the thunderstorm and that the number of patients with asthma or other airways disease presenting during a 30 hour period increased about 10-fold. Most of the patients studied were young adults, and most were atopic; about half were not known to have previously had asthma. These findings are consistent with the view that thunderstorm associated asthma is related to aeroallergen levels. Although most patients were not seriously ill, the epidemic presented a serious challenge to accident and emergency departments - several ran out of equipment or drugs or had to call in additional doctors.

Thunderstorm associated asthma is a separate entity

Accounts of asthma epidemics around the world have related asthma presentations to various environmental factors, including meteorological events. On p 604 Celenza et al examine the 18-fold increase in patients who presented with asthma to a London accident and emergency department during the 24 hours after a thunderstorm in June 1994. The asthma epidemic was significantly associated with a fall in air temperature six hours before patients' presentation and a high grass pollen concentration nine hours before. Asthma presentations over the two months surrounding the epidemic showed associations with lightning strikes, increased humidity, decreased air temperature and pressure, and rainfall, as well as rises in sulphur dioxide concentration and changes in grass pollen count. The two populations may therefore be different, with airways sensitive to a different range of environmental changes.

Cognitive impairment predicts risk of death from stroke in elderly people

Elderly people with poor cognitive performance have a high mortality. But the reasons for this are unclear. Gale et al (p 608) followed up 921 people whose diet had been assessed in the 1970s and analysed their subsequent mortality. Cognitive impairment was a strong risk factor for death from stroke but not for death from other major causes. Low dietary intake of vitamin C, a major antioxidant, was also an important predictor of death from stroke. Cognitive performance was poorest in people with the lowest intake of vitamin C. Atherosclerotic disease is thought to be responsible for a considerable amount of cognitive impairment in elderly populations. Antioxidant vitamins may prevent atherosclerosis by protecting low density lipoproteins from free radical attack. Improving the diet of elderly people may be one way of reducing their risk of both cognitive impairment and cerebrovascular disease.

Equitable preventive care among ethnic groups is possible

Few studies have documented preventive care delivered by general practitioners to different ethnic groups. On p 614 Atri et al of the healthy eastenders project describe their findings in one inner London Borough with some of the worst deprivation in the country. They found major socioeconomic inequalities between white people and those in minority ethnic groups, but there was little evidence of substantive inequity in the delivery of preventive care for the major causes of death by selected general practitioners. Mammography and cervical cytology were exceptions and require additional support at practice level.