Saturday, October 17, 2009

Non-urban dwellers living near parks are healthier and less depressed

Another variation on an old theme. You would never guess from the media report below that this did NOT apply to city-dwellers (dwellers in "strongly urban areas"), which is an example of why it is important to go back to the original journal article, and the "Results" section of the article at that. I have found many times over the years that the conclusions don't reflect the results. So the findings in fact DISPROVE the claim that green surroundings are generally beneficial. The only reasonable conclusion from the research is that the minority who live in or near the countryside ("slightly urban areas") do so in part because it makes them feel better, which is not much of a discovery. It is just a finding of individual differences, not a finding about greenery in general. Some people like the countryside and some don't

City dwellers living near parks are healthier and suffer fewer bouts of depression, a study has revealed. The study was adjusted to take into account socio-economic background and found that the effect of green surroundings was greatest for people with low levels of education and income.

The study, published in the Journal of Epidemiology and Community Health, found that in urban zones where 90 per cent of the area was green space the incidence of anxiety disorders or depression was 18 people per thousand. In areas with only 10 per cent greenery the incidence was 26 per thousand.

The annual rates of more than a dozen disease types, including cardiovascular, respiratory, neurological, digestive and mental disorders, were also lower for those living near parks. The impact on health was most marked in people who spent a lot of time in their green surroundings, especially children and people aged 45 to 65.

The findings are based on health records in the Netherlands for nearly 350,000 people registered with 195 family doctors in 95 practices across the country. “The role of green space in the living environment should not be underestimated,” the study concludes.


Abstract follows:

Morbidity is related to a green living environment

By Jolanda Maas1 et al.

Background: Due to increasing urbanisation, people face the prospect of living in environments with few green spaces. There is increasing evidence for a positive relation between green space in people's living environment and self-reported indicators of physical and mental health. This study investigates whether physician assessed morbidity is also related to green space in people's living environment.

Methods: Morbidity data were derived from electronic medical records of 195 general practitioners in 96 Dutch practices, serving a population of 345,143 people. Morbidity was classified by the general practitioners according to the International Classification of Primary Care (ICPC). The percentage of green space within a one kilometre and three kilometre radius around the postal code coordinates was derived from an existing database and was calculated for each household. Multilevel logistic regression analyses were performed controlling for demographic and socio-economic characteristics.

Results: The annual prevalence rate of 15 of the 24 disease clusters was lower in living environments with more green space in a 1 km radius. The relation was strongest for anxiety disorder and depression. The relation was stronger for children and people with a lower socio-economic status. Furthermore, the relation was strongest in slightly urban areas and not apparent in very strongly urban areas.

Conclusion: This study indicates that the previously established relation between green space and a number of self-reported general indicators of physical and mental health can also be found for clusters of specific physician assessed morbidity. The study stresses the importance of green space close to home for children and lower socio-economic groups.

J. Epidemiol. Community Health, 2009

The mechanics of the placebo effect

If you thought the placebo effect was all in the mind, think again. Scientists have solved the mystery of why some people benefit from remedies that do not contain any active pain-relief ingredients. Research suggests that placebos work, in part, by blocking pain signals in the spinal cord from arriving at the brain in the first place. When patients expect a treatment to be effective the brain area responsible for pain control is activated, causing the release of natural endorphins.

The endorphins send a cascade of instructions down to the spinal cord to suppress incoming pain signals and patients feel better whether or not the treatment had any direct effect. The sequence of events in the brain closely mirrors the way opioid drugs, such as morphine, work — adding weight to the view that the placebo effect is grounded in physiology.

The finding strengthens the argument that many established medical treatments derive part of their effectiveness from the patients’ expectation that the drugs will make them better.

The latest studies on antidepressants suggest that at least 75 per cent of the benefit comes from the placebo effect. GPs also observe that patients report feeling better only days after being prescribed antidepressants, even though the direct effects take several weeks to kick in.

In the study, published today in the journal Science, the spinal cords of 15 healthy volunteers were scanned using functional magnetic resonance imaging (MRI). The scan homed in on an area called the dorsal horn, which transmits pain signals coming up through the spinal cord into the pain-related areas in the brain.

During the scan, the volunteers received laser “pinpricks” to their hands. The volunteers were told that a pain-relief cream had been applied to one of their hands and a control cream to the other. But unknown to the volunteers, an identical control cream was administered to both hands.

When people believed that they had received the active cream, they reported feeling 25 per cent less pain and showed significantly reduced activity in the spinal cord pathway that processes pain.

Previously, it has been shown that placebo causes the release of natural opioids in areas of the brain involved in pain control, such as the rostral anterior cingulate cortex. However, it was not known whether the natural opioids acted on the spinal cord in the same way as artificial painkillers or whether they simply changed people’s tolerance or interpretation of pain. “We’ve shown that psychological factors can influence pain at the earliest stage of the central nervous system, in a similar way to drugs like morphine,” said Falk Eippert, of the University Medical Centre Hamburg-Eppendorf, who led the study.

Until now, the difficulty of obtaining MRI images of the spinal cord, because of its small size and its being surrounded by airways and pulsating arteries, prevented this question from being addressed. However, advances in image processing allowed the Hamburg team to obtain high resolution scans of the region.

The advance in imaging techniques is likely to have important applications for drug development. Pharmaceutical companies are working to develop new anaesthetic drugs that target the pain pathways in the spinal cord. Being able to image this area of the body provides a direct way of testing whether the drugs are working as intended.

The findings will continue to fuel debate over the prescription of “sugar pill” cures. In a study in 2005, 48 per cent of Danish GPs admitted having prescribed a placebo at least ten times in a year. A variety of placebo cures, such as Obecalp pills for children, are also available on the internet.


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