Press releases Monday 9 February to Friday 13 February 2009
Please remember to credit the BMJ as source when publicising an article and to tell your readers that they can read its full text on the journal's website (http://www.bmj.com).
(1) Second-hand smoke could cause dementia
(2) Few women follow healthy lifestyle guidelines before pregnancy
(3) Publication of flu vaccines studies in prestigious journals are determined by the sponsor
(1) Second-hand smoke could cause dementia
(Research: Exposure to second-hand smoke and cognitive impairment in non-smokers: national cross sectional study with cotinine measurement)
http://www.bmj.com/cgi/doi/10.1136/bmj.b462
(Editorial: Passive smoking and cognitive impairment)
http://www.bmj.com/cgi/doi/10.1136/bmj.a3070
Exposure to second-hand smoke could increase the risk of developing dementia and other forms of cognitive impairment, according to research published today on bmj.com.
A possible link between active smoking and cognitive impairment has already been established and previous findings also suggest that second-hand smoke exposure could be linked to poor cognitive performance in children and adolescents. However, this is the first large-scale study to conclude that second-hand smoke exposure could lead to dementia and other neurological problems.
The authors, Dr David Llewellyn and his research team from the University of Cambridge, Peninsula Medical School and the University of Michigan, examined saliva samples from almost 5000 non-smoking adults over the age of 50 using data from the 1998, 1999 and 2001 waves of the Health Survey for England (HSE). The participants had also taken part in the English Longitudinal Study of Ageing (ELSA).
The samples were tested for cotinine - a product of nicotine that can be found in saliva for about 25 hours after exposure to second-hand smoke. Participants in the study also provided a detailed smoking history. Never smokers and previous smokers were assessed separately.
The researchers used established neuropsychological tests to assess brain function and cognitive impairment. These focused on memory function, numeracy and verbal fluency - for example naming as many animals in a minute. The results of the tests were added together to provide a global cognitive function score.
Participants whose scores were in the lowest 10% were defined as suffering from some level of cognitive impairment.
The authors argue that the link between second-hand smoke and cognitive impairment could be explained given that heart disease increases the risk of developing dementia and second-hand smoke exposure is known to cause heart disease.
In an accompanying editorial, Dr Mark Eisner from the University of California, says that while the serious negative health effects of second-hand smoke like cancer and premature death have been established beyond doubt, there is still a lot to learn about the scale of illness caused by second-hand smoke.
He writes: "Emerging evidence suggests that parental smoking may impair childhood cognitive development. Later in life, second-hand smoke may cause cardiovascular disease and stroke, which are themselves linked to cognitive decline. Until now, however, the suspicion that passive smoking is bad for the adult brain had not been scientifically confirmed."
Eisner concludes by hoping that greater public awareness about the dangers of second-hand smoke, especially awareness about a much feared disease like dementia, "would eventually translate into political action aimed at passing smoke-free legislation in regions of the world where public smoking is still permitted."
Contacts:
Research: Dr David Llewellyn, Research Associate, Institute of Public Health, University of Cambridge, UK
Email: dl355@medschl.cam.ac.uk
Or
Dr Iain Lang, Research Fellow, Epidemiology & Public Health Group, Peninsula Medical School, UK
Email: iain.lang@pms.ac.uk
Very few women follow the nutritional and lifestyle recommendations before they become pregnant, even when pregnancy is in some sense planned, finds a study published on bmj.com today.
Nutrition and lifestyle advice is widely available for women during pregnancy, but much less emphasis is given to advice for women who may become pregnant. Yet promoting good health and nutrition before pregnancy may be at least as important as during pregnancy as the time around conception is vital for the development of the baby.
So researchers at the MRC Epidemiology Resource Centre at the University of Southampton set out to examine the degree to which women comply with these recommendations before they become pregnant.
Between 1998 and 2002, they interviewed 12,445 non-pregnant women aged 20-34 years as part of a general survey on health. Information on their diet, physical activity, smoking, alcohol consumption and nutritional supplement use over the past three months was recorded.
A total of 238 women became pregnant within three months of interview. These women were compared with those who did not become pregnant.
The women who became pregnant were only marginally more likely to comply with the alcohol and folic acid recommendations than those who did not become pregnant. Among those who became pregnant only seven (2.9%) were taking the recommended daily dose of 400µg folic acid and drinking no more than four units of alcohol per week, compared with 0.66% of those who did not become pregnant.
The women who became pregnant were slightly less likely to smoke than those who did not become pregnant (74% v 69% were non-smokers) but this difference was not statistically significant.
Women in both groups were equally likely to consume five or more portions of fruit and vegetables per day, but only 57% of those who became pregnant had taken any strenuous exercise in the past three months compared with 64% of those who did not become pregnant.
At interview, 55 (23%) of the 238 women who became pregnant said that they did not anticipate trying for a baby in the next 12 months. Among this ‘unplanned' group only one woman (1.8%) who became pregnant complied with the alcohol and folic acid recommendations, but among the remainder, who were, in some sense, ‘planning' a pregnancy, the percentage was only slightly higher at 3.3% (six women).
In conclusion, our data show limited evidence of changes in health behaviours before pregnancy, say the authors. They call for greater publicity for pre-pregnancy recommendations, but point out that substantial unplanned pregnancy rates mean that greater efforts are needed to improve the nutrition and lifestyles of all women of child-bearing age.
In an accompanying editorial, public health experts from the University of Southern Denmark believe there is a need to reconsider the timing and setting for public health campaigns aimed at improving the conditions for the developing fetus. They also suggest that it is time to not only focus on women, but include men as targets for health promotion too.
Contacts:
Research: Hazel Inskip, Professor of Statistical Epidemiology, MRC Epidemiology Resource Centre, University of Southampton, Southampton, UK
Email: hmi@mrc.soton.ac.uk
Or
MRC Press Office, Hazel Lambert
Email: Hazel.Lambert@headoffice.mrc.ac.uk
Or
University of Southampton Communications, Sarah Watts
Email: s.a.watts@soton.ac.uk
Editorial: Editorial: Camilla Bille, PhD, Epidemiology, Department of Public Health, University of Southern Denmark, Odense, Denmark
Email: Cbille@health.sdu.dk
(3) Publication of flu vaccines studies in prestigious journals are determined by the sponsor
(Research: Relation of study quality, concordance, take home message, funding, and impact in studies of influenza vaccines: systematic review)
Industry-sponsored studies on influenza vaccines are published in journals with higher rankings (impact factors) and are cited more than studies with other sponsors, but this is not because they are bigger or better, finds a study published on bmj.com today.
Tom Jefferson and colleagues at the Cochrane Vaccine Field in Italy identified and assessed 274 studies on influenza vaccines and analysed their methodological quality, prestige of the host journals (impact factor) and citation rates in the scientific literature.
They found no relationship between study quality, publication in prestige journals or their subsequent citation in other articles. They also found that influenza vaccine studies are of poor quality and those with conclusions in favour of the vaccines are of significantly lower methodological quality.
The single most important determinant of where the studies were published or how much they were cited was sponsorship. Those partially or wholly funded by industry had higher visibility.
The researchers also found no relationship between journal impact factor and the quality of the influenza vaccine studies it publishes, suggesting that the impact factor is not the robust quality indicator that publishers suggest and confirming some of the widely expressed doubts on its appropriateness as a means of rewarding researchers with promotions and funds.
Dr Jefferson concludes: "The study shows that one of the levers for accessing prestige journals is the financial size of your sponsor. Pharmaceutical sponsors order many reprints of studies supporting their products, often with in-house translations into many languages. They will also purchase publicity space on the journal. Many publishers openly advertise these services on their website. It is time journals made a full disclosure of their sources of funding."
Contact:
Dr Tom Jefferson, Cochrane Vaccines Field, Roma, Italy
Email: Jefferson.tom@gmail.com
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