Dei'ah veDibur - Information & Insight

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6 Kislev 5766 - December 7, 2005 | Mordecai Plaut, director Published Weekly










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Home and Family

Studies Show . . .
by L. Raffles

What does it mean when we read that 'studies show . . . . X, Y and Z?' Are we given enough information in these reports to really understand what the study shows?

There are two main types of studies done by scientists. One is when they select a group and test something on the group and look at what happens. The second is when they look at how people live, and the illnesses they get, and try to establish what people are doing which gives them a greater risk of getting some condition. In its simplest form, they will look at as many people as possible who have a condition, and then see if they can find a common thread.

When scientists want to test if a particular medicine or procedure works, they run a trial. A proper study can only be considered conclusive if a double blind trial is run. This is where you take a group of individuals, the larger the group the more reliable the results, and you match them as much as possible for age, gender, other health issues, race, financial status, education and anything else you can. The more matched the group, the less complicated it is to understand and rely on the results. Then the group is split at random, and one group is given the real medicine, and the other group is given a placebo.

A placebo looks exactly like the medicine, but is usually made of some sort of sugar, with a taste to fool the patient that he is getting real medicine. To make the results even more reliable, the doctor who gives out the medicine also does not know if he is giving the real one or the placebo. This is called the 'double blind'; both the patient and the administering doctor are 'blind' as to the type of tablet being used.

The researchers then look at the improvement in both groups. The interesting thing is that we are not surprised to sometimes see an improvement in some people in the group given the placebo. What we look for are statistically significant differences between the two groups. Many studies are stopped early, on ethical grounds, when early results show such a marked improvement in the medicated group that it is considered immoral for the other group to miss out on that benefit, especially in cases where the difference may be a matter of life and death.

A correctly constructed study should have clear criteria for defining the 'problem' and what constitutes improvement. It is best when these results involve numbers that can then be tabulated and compared statistically, rather than general, subjective, descriptions of 'feeling better.'

An example of this type of study is a trial to look at the ability of a certain medicine (Medicine A) to control high blood pressure. We find a group of a hundred overweight, white, middle-class men, fifty of whom receive Medicine A, and fifty of whom (the control group) take the placebo. The results might show that those who took Medicine A had lower blood pressure after a month, on average, compared to those in the control group (who took the placebo). Interpreting these results does not take a lot of skill, and is quite straightforward.

However, in the second type of study, the researchers try to find links between certain lifestyles (smoking, exercise, watching TV, eating raw fish) and healthy blood pressure. In a study such as this you get results like, "The Japanese, who eat a lot of raw fish, have lower blood pressure than American men who do not eat raw fish." This can then be interpreted as meaning 'raw fish lowers high blood pressure.' However there may be so many other differences between American and Japanese diets and lifestyles that the raw fish cannot be shown, by this study, to have a direct causal link with lower blood pressure.

It's like understanding the difference between the following two statements: 1) "Most people who get lung cancer are smokers" and 2) "Most smokers get lung cancer." These statements are not the same. The former shows a link between smoking and lung cancer, and suggests that if you smoke you should give it up, as you may get lung cancer. However, the latter statement suggests that if you smoke, you will get lung cancer, and that if you don't smoke, you won't.

The first statement is true while the second is not. There are those who smoke, and will not get lung cancer, and there are people who get lung cancer who never smoked (and did not suffer from passive smoking either). The first statement may be the conclusion of a study (written up with appropriate percentages and statistics), printed in a learned periodical, while the latter may be the headline in newspapers.

The second problem with understanding studies is the 'placebo effect.' Going back to the study on Medicine A for the treatment of high blood pressure, it would be quite normal for some in the control group to have some improvement in their blood pressure. The improvement in a few individuals might even be as good as in the medicated group. However statistically, when looking at the group as a whole, there will not be as great an improvement for as many people, in the control group, as compared to the medicated group. The reverse is true for the medicated group — some in that group will not be helped, either at all, or not as much as others. How people respond to medicine is very variable.

This placebo effect is very difficult to explain. For some reason, certain individuals improve without any medication, because they believe that they are taking medication. In fact, there will be some individuals who spontaneously improve even if they take nothing (not even a placebo). Even what the doctor knows seems to have an influence on the results. That is why a "double blind" is used, where the doctors also don't know whether they are giving the placebo or the real medicine.

Studies most often establish statistical links, which is not the same as proving 'cause and effect.' The debate about smoking raged for so long because although it was easy to prove a link between certain diseases and smoking, it was harder to prove that one directly caused the other. As long as that proof didn't exist, tobacco companies chose to interpret the results in a way that was less damaging to their business. The tobacco companies themselves did a lot of the early research, and that raised many issues about how totally reliable the results were.

Take an absurd example. There are certain illnesses that are more prevalent among those of greater wealth, and other illnesses that seem to affect poorer people more. Taken at face value, we could say that it is the money itself, or lack of it, that is making these people ill. That would be a "cause and effect" argument. However, it is clear that we cannot see a logical way of that being so. Therefore it must be something in the lifestyle of rich people that makes them prone to those illnesses, and likewise for the poor.

Poor people buy less fresh fruit and vegetables, visit the doctor less often (they can't afford the time off work, and are less educated about illnesses for which they should seek help), have more unhealthy jobs (involving dust, heat, vibration etc) and are more likely to smoke. Rich people are more likely to eat heavy, rich (in both meanings of the word!) meals, have high-stress jobs and have high blood pressure. Finding the actual factor that causes any particular illness is very difficult.

This is how they formed the link between crib death (SID — Sudden Infant Death) and laying the child on its tummy. This is not to say that they know why they are linked, or even that it is 'cause and effect,' but only that it showed up strongly in the statistics, and after the education program was run to teach mothers to put their babies on their back, the number of crib deaths fell dramatically. That is not to say that all babies who sleep on their tummies are at risk, or that babies don't also sometimes die when on their back. It's a statistic.

In newspapers (less common in respectable secular papers), studies are written up without any explanation of what type of study it was, how many people were involved or what type of results were achieved. No source is given, so the original paper cannot be checked (that's assuming we could understand it if we did read it). We just get a sort of 'headline' that is often an interpretation rather than a result, and this is very much influenced by the prejudices of the writer. We are told "studies show . . . ." but are given no way to decide how conclusive these studies are. This obscuration and misinterpretation of results are common for studies involving food supplements, alternative remedies and issues surrounding childbirth.

For example, although many food supplements may have an effect on a particular condition, given what we know about the placebo effect, we need to know if the results from using this supplement are more than the placebo affect. Was the condition being treated clearly defined? Was the improvement clearly measurable? Was a double blind used? The fact that someone was helped is great for that person, but does not constitute evidence that it will help someone else. Likewise, even a medicine that has been proven to be effectual will still be unhelpful for some people. The fact that you know someone who wasn't helped doesn't mean it won't help you.

It is by the very nature of some of these things that it is very difficult to run large-scale double blind trials, and that certainly doesn't mean that they are not effective, just that it is difficult to prove. One ends up taking the attitude "it's worth a try," or "if it works for me then it doesn't matter why, or whether it's just the placebo effect."

Knowing the results of a study still does not always mean we really understand what is going on. People who have their own axe to grind often interpret the results for us. The media or advertising industry often distorts or misinterprets the results of studies, either from ignorance or because they have an agenda of their own. It is important to try and be an "informed consumer," or at least a sceptical one, particularly if the underlying purpose of telling us these "study results" is to sell us something.

An Interesting Study

Oxford University's physiology department conducted the following study. First they assessed 100 children, of normal ability, who were underachievers in reading and were also suspected of being dyspraxic (which is a problem with motor planning and coordination). Then they divided the children into two groups, at random.

They gave half the children a supplement of Omega 3 fatty acids, and half the children a placebo (a fake tablet). Neither the children nor the researchers administering the tablets knew who was in each group. 40% of the group given the supplements made dramatic improvement, averaging nine months progress in three months. The control group (given the placebo) made the normal three months progress. After three months, the control group were also switched to the supplements and showed similar leaps in progress.

Although none of the children had been diagnosed as having ADHD, about a third of the children had sufficient problems to suggest that they had an attention disorder. During the course of the trial, about half of these children made enough progress for them not to be considered in that category anymore. This is on par for results from Ritalin.

The underlying mechanism at work here seems to be the fact that the brain and retina, at the back of the eye, are filled with neurones, which are the wiring of the brain, and these fatty acids play an important role in these neurones being able to work and to transmit to each other.

In a separate, well-controlled, double blind placebo trial, Omega 3 fatty acid supplements were given to prisoners who had a history of violence while in prison. The number of serious offences, including violence, in the group taking the supplements dropped by 40%, but not at all in the control group.

Why should we need to take a supplement when everything we need should be available in our diet? Also, if children in the same family eat the same diet, why don't they all have the same problems? In answer to the first question, our diets have changed over the years, and we leave out a lot of things we used to eat. Omega 3 fatty acids are found in oily fish, nuts, seeds and leafy vegetables (though fish is the richest source) and these foods used to be a bigger part of our diet. Also, they are very sensitive chemicals and break down easily during food processing. In answer to the second question, there are indications that some people inherit a predisposition to being deficient, even when sufficient quantities are available in the diet.

It is important to note that although 40% of the children made these significant improvements, 60% didn't, and therefore it is not going to be a panacea. Secondly, although there were children with attention deficiency who improved with supplements, and this was statistically the same improvement seen with Ritalin, we don't know if the same children who would benefit from Ritalin are those who would benefit from supplements. It might be a different half.

We would have to study children on Ritalin, half of whom are then taken off it and given these supplements instead, and half given a placebo, and then see how they respond. Anyone considering this switch should seek professional advice first, as altering the treatment regime of a child can have serious behavioral and emotional consequences. However, if you have a child who has not yet started any treatment for attention deficiency, or who has dyslexia, dyspraxia or behavioral problems, then this may be "worth a try."

(Sources for the study on Omega 3 fatty acids available on request ++44 191 477 5239.)


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