Does the Pill make women stupid?

Baby pictureThe following is a list of common symptoms of taking the oral contraceptive pill (“The Pill”), except for one of them. Can you guess which one is not listed in the package insert?
  • Nausea
  • Headaches
  • Mood Changes
  • Tender Breasts
  • Increased Appetite
  • Feeling Bloated
  • Gaining Weight
  • Stupidity

Wait, don’t answer now, there’s something I want to tell you first.

When you read something interesting on the internet, don’t run off and write a lazy, potentially dangerous info page designed to scare people. And if you do decide to write a three line shock piece, at least try and be responsible with your headlines! This is precicely what News24 did NOT do when they published this page entitled “The Pill Makes You Stupid. Fact!”. This “article” is so short that I will reproduce it here:

A recent study published in the journal Brain Research reveals that the effect of the oral contraceptive on the brain is likely to be extensive.

The report found that our faithful pilletjie has structural effects on parts of the brain that controls higher-order cognitive activities, suggesting that a woman taking it may not be herself – or is herself, on steroids.

Shocked? So are we!

As a regular user of the Pill I thought I had better check this out. So I followed the link provided by News24 for the study and I found myself at the Scientific American website. I like the SciAm website and was quite happy to read their excellent article about how the pill makes women stupid. What I found, however, made me pretty upset. It seems as though the person at News24 responsible for putting together the shock article above had not bothered to read more than the first two paragraphs of the SciAm article; which she copied almost word for word.

She certainly didn’t read as far as the sentence which states:

Again, we do not know whether this increased gray matter translates into better or worse performance

Well, I did. In fact, I read the SciAm article twice AND read the abstract of the paper (Menstrual cycle and hormonal contraceptive use modulate human brain structure, Pletzer. B et al, Brain Research 12 August 2010) and I did not come to the conclusion that The pill makes women stupid. Fact! I came to a very different  conclusion.

Before I go any further let me give you the executive overview of the findings of this study (as I understand it): fMRI scans of the brains of 14 women using the pill were compared to those of 14 men and 14 women not using the pill and they found that women using hormonal contraceptives showed “significantly larger prefrontal cortices, pre- and post central gyri, parahippocampal and fusiform gyri and temporal regions” than naturally cycling women.

Wait! Wait! Don’t run away yet, I will explain what each of those regions of the brain does.

The brain - showing the Prefrontal cortex

The prefrontal cortex is the front part of the brain and it is responsible for executive functions: mediating conflicting thoughts, deciding between right and wrong, and governing social control. This is one important little squishy bit.  A sixfold increase in the size of the prefrontal cortex over the past five million years of hominid evolution has led scientists to believe that there is significant selection pressure favoring it’s continued growth.

The following two images represent the lateral and medial surfaces of the cerebral cortex, basically the inside and outside of your grey matter. The cerebral cortex is folded in on itself to allow for more processing power in a smaller space and at a higher speed. The ridges formed by the folds are called gyri.

Lateral Surface of Cerebral Cortex

The primary motor cortex is located in the precentral gyrus which controls voluntary movement.

The postcentral gyrus receives sensory information from the skin and muscles.

The parahippocampal gyrus is important for the encoding and retrieval of memories.

The role of the fusiform gyrus is disputed, but it does seem to play a role in the recognition of colours, faces, words and numbers.

Finally, the temporal lobe is important for auditory perception, processing semantics in speech and vision, and it plays a key role in the formation of long term memories.

Medial Surface of Cerebral Cortex

It would be a very bad thing for you to suffer any damage to any of these parts of your brain. And a study which investigates a potentially harmful effect to all of them should be a  rigorous exercise. That’s where I am a little concerned about the findings of the Pletzer study.

My main concern is the size of the study; 42 participants is a very small number. When you are putting a study together you need to make sure that you have enough participants to ensure a statistically significant result. The more people you have, the less weight an “outlier” will have on the study. A general rule of thumb is that you should have 20 times as many subjects as variables in your study. I do not have access to the full text of the paper, but SciAm points out quite a few variables which do not seem to have been accounted for:

  1. The authors did not examine levels of circulating hormones in the male and female subjects.
  2. The hormonal contraceptives were all considered in a single group instead of accounting for the different ratios in levels of estrogen and progesterones in birth control pills.

Those are two broad categories of variables which were not accounted for and they are not the only procedural slip ups in the paper. Other serious errors are:

  1. The authors did not perform behavioral or cognitive tests of their subjects. Such tests may account for the meaning or functional consequences of the changes.
  2. Birth Control pills keep the natural levels of hormones low, this confounds the data. The lower levels of natural hormones might account for the structural changes and the hormonal contraceptives might be innocent.

Despite it’s flaws, however, Pletzer’s study does reinforce the fact that we need to carefully consider the effects of the drugs we take. I would love to see more research into this subject because it is extremely important. For now, I will continue to take the advice of my doctor and I will not allow lazy journalism and sensation seeking headline writing to dictate the medical decisions I make for my body.

P.S. In case you are wondering, “Stupidity” is the answer to the mini-quiz at the beginning of this article.

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9 responses to “Does the Pill make women stupid?

  1. Hi Angela,

    You concern about sample size is a little strange. Two questions:

    1) Where on earth did you get that rule of thumb from? It sounds like somebody just made it up. Google doesn’t seem to know about it either. What power is it meant to achieve, and for what effect size?

    2) Was their result significant? If it was, then the sample was large enough. The p-value – the probability of obtaining a result that extreme assuming the null is true – takes sample size into account. If they are getting a significant result with a small sample then the variation within groups must have been quite small compared to that between. If outliers are a concern, then use an appropriate distribution or a non-parametric test.

    I’ve just taken a look at the actual paper (free pdf at 6th link on a google search for the title). If there is anything to complain about it is the multiple comparisons issue. They use FDR control but don’t say much about it.

    Sorry if this sounds peeved, but scanner work is expensive. If they got a significant result, then they pitched correctly. A larger sample would have been a waste. Rather let the money be used on a followup. You’re not helping with that level of criticism. Pointing out fictitious problems with a paper (that you haven’t read!) is just another kind of journalistic sensationalism: one geared to impress a different audience.

    • Thank you for your feedback. I got the rule of thumb from a friend who is busy doing his Master’s degree in Cognitive Science. I am a layman and try to gather the best information I can, but obviously this is a learning process for me as well.

      I apologise if you find my criticism harsh, I just think it is a bit of a leap to take less then fifty people for a trial on how a drug changes our brain’s structure and function, and decide that you have a significant representation of the population at large.

      • > I apologise if you find my criticism harsh

        Not harsh. Just misguided.

        > I just think it is a bit of a leap to take less then fifty people for a trial on how a drug changes our brain’s structure and function, and decide that you have a significant representation of the population at large.

        But you would trust the result if they got the same p-value with a much larger sample? If not, then your objection is to what is considered an acceptable p-value, not the sample size. If you would, then you have misunderstood something.

        > I got the rule of thumb from a friend who is busy doing his Master’s degree in Cognitive Science.

        I hope nobody lets him do science.

    • Yeah, they seem to be really lazy and irresponsible. I actually frequent News24 for the sole purpose of harvesting material to write about here.

      Thank you for the compliment.

      • Speaking of lazy and irresponsible, funny how you came to your own conclusions without having access to the article to begin with.

  2. I think perhaps the unnamed author of the News24 article is suffering from stupidity.

    Whether or not that’s linked to the birth control pill is another question.

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