Approximately 40% of the people affected by Parkinson’s are female. This number can vary across regions, but women still make up a large portion of the affected community.
That said, there is unfortunately very little research investigating women’s issues in Parkinson’s.
There are now efforts to correct this situation, however, and this change is being brought about by members of the affected community.
In today’s post, we will discuss some of what is known about how Parkinson’s affects women differently.
Why is today – the 8th March – called International women’s day? (backdated due to @#%$£&* technical issues!).
I don’t actually know. Perhaps because it’s politically correct that everyone should get their own day/month now?
The United Nations began celebrating International Women’s Day on the 8th March in 1975. But observation of the day date back to the early years of that century, and although the suffrage movement was occurring at the same time, International women’s day was very much a socialist idea.
And this shows itself in the timeline of events. For example, International Women’s Day was first observed on the 19th March, 1911 in Germany thanks to socialist activists like Luise Zietz, Käte Duncker and Clara Zetkin. But it wasn’t until 1918 that women were actually given the right to vote.
And remarkably, it was not until 1977 that the United Nations General Assembly invited its member states to proclaim the 8th March as the “UN Day for women’s rights and world peace”.
Interesting. But what does this have to do with Parkinson’s?
There is an imbalance in the amount of research being conducted on women in Parkinson’s.
In particular, there is a poverty of information regarding aspects of daily life for women living with Parkinson’s, especially those with young onset Parkinson’s.
What do you mean?
If you go to the medical research search engine Pubmed, and type in Parkinson’s and menopause, there are only 107 publications (dating back to 1971, 41 of them since 2010). To put that in context, there are over 105,000 research reports on Parkinson’s on the pubmed database. And most of them are not about menopause research, they simply mention the word menopause in their text. Similarly there are only 25 reports on parkinson’s and menstruation (and only 6 of them have been conducted since 2000!?!?).
Searching for male associated key words such as parkinson’s and prostate yeilds 177 publications (104 of which have been published since 2010 only).
And searching for Parkinson’s and male results in 43,000 reports, but searching for Parkinson’s and female only gives 36,000 reports.
So why the disparity?
At the bottom of our previous post, we mentioned that Japan is the only country where women have a higher incidence of Parkinson’s disease than men.
We also suggested that we have no idea why this difference exists. Well, a study presented at the Cardiovascular, Renal and Metabolic Diseases conference in Annapolis City (Maryland) last week may now be able to explain why this is.
The prevalence of Alzheimer’s disease is significantly higher in women compared to men. One recent estimate suggested that almost two-thirds of individuals diagnosed with Alzheimer’s disease are women (More information here). One possible reason for this is that Alzheimer’s disease is a condition of the elderly and women live longer.
So why is it then is the exact opposite true in Parkinson’s disease???
Source: The Telegraph Newspaper
Men are approximately twice as likely to develop Parkinson’s disease as females (More information here)
In addition, women are on average diagnosed 2 years later than men (More information here)
This gender difference has long puzzled the Parkinson’s research community. But now a group from the University of North Texas Health Science Center think that they may have the answer.
The researchers – lead by Shaletha Holmes from Dr Rebecca Cunningham’s lab – observed that when they stressed dopamine neurons, adding the male hormone testosterone made the damage worse. Interestingly, they found that testosterone was doing this by acting on a protein called cyclooxygenase 2 (or COX2). When they blocked the actions of COX2 while stressing dopamine neurons, they found that they also blocked the damaging effect of testosterone. The researchers concluded that testosterone may exacerbate the damage (and death) in dopamine neurons that occurs in Parkinson’s disease, thus possibly explaining the sex differences described above.
Now, there are several interesting aspects to this finding:
Firstly, the use of Ibuprofen, the nonsteroidal anti-inflammatory drug used for relieving pain, has long been associated with reducing the risk of Parkinson’s disease (More information here).
Ibuprofen is a COX2 inhibitor.
But more importantly, several years ago it was shown that Japanese men have lower levels of testosterone than their Western equivalents. Here is the study:
Title: Evidence for geographical and racial variation in serum sex steroid levels in older men.
Authors: Orwoll ES, Nielson CM, Labrie F, Barrett-Connor E, Cauley JA, Cummings SR, Ensrud K, Karlsson M, Lau E, Leung PC, Lunggren O, Mellström D, Patrick AL, Stefanick ML, Nakamura K, Yoshimura N, Zmuda J, Vandenput L, Ohlsson C; Osteoporotic Fractures in Men (MrOS) Research Group.
Journal: Journal of Clinical Endocrinol. Metab. 2010 Oct;95(10):E151-60.
The study suggested that total testosterone levels (while similar in men from Sweden, Tobago and the US) were 16 per cent higher in men from Hong Kong and Japan. BUT – and here’s the catch – Japanese men also had higher levels of a testosterone-binding hormone (Sex hormone-binding globulin or SHBG), so there is less of the testosterone floating around free to act. As a result, Japanese men had the lowest levels of active testosterone in the study.
Intriguingly, the researchers found that Japanese men who emigrated to the US had similar testosterone levels to men of European descent, suggesting that environmental influences may be having an effect of testosterone levels. Diet perhaps?
If testosterone is found to play a role in the gender difference found in Parkinson’s disease, the lower levels of free testosterone observed in Japanese men may explain why women in Japan have a higher risk of Parkinson’s disease than men.
EDITOR’S NOTE: WHILE WE HAVE NO DOUBTS REGARDING THE RESEARCH OF DR CUNNINGHAM AND HER GROUP, WE ARE TAKING A LEAP IN THIS POST BY APPLYING THE TESTOSTERONE RESULTS TO THE GENDER DIFFERENCE IN JAPAN. THIS IS PURE SPECULATION ON OUR PART. WE HAVE SIMPLY SAT DOWN AND TRIED TO NUT OUT POSSIBLE REASONS AS TO WHY THERE IS A REVERSED GENDER DIFFERENCE FOR PARKINSON’S DISEASE IN JAPAN. OUR THEORY IS YET TO BE TESTED, AND MAY BE COMPLETELY BONKERS. WE PRESENT IT HERE PURELY FOR DISCUSSION SAKE AND WELCOME YOUR THOUGHTS.