Something odd happens when I tell people I have Parkinson’s.
Lots of them reply
with “oh yes, my grandfather had Parkinson’s,” or “my father-in-law had it” or
“somebody I work with has Parkinson’s”.
It seems that
everybody knows somebody with the disease.
Given that the
official statistic in the UK (according to Parkinson’s UK) is that it affects
around 1 in 350 adults, what is going on here? Anecdotally, it feels as is far
more than this number have Parkinson’s. Or is some strange mathematical network
effect at play?
Take a
recent lunch as an example. I catch up once a year with a group of friends that
I used to work with. At the last reunion there were 14 of us and I decided to
share my news with the other 13. Two of
the 13 cited relatives who had the disease, in one case a father-in-law and in
another case a grandparent.
So, let’s do the math…
Each person in my
group of friends has two parents and four grandparents and usually a spouse or
partner with the same. That’s 14 people (including themselves). If we throw in an average of one sibling plus
partner’s sibling, their partners and the additional parents and grandparents
we get another 16 people, or 30 in total.
Out of my group of 13
that adds up to 390 people so you would typically expect one of them to cite a close
relative with Parkinson’s. To have two in the group does not seem statistically
particularly unusual, especially when you consider that I have not counted
step-families, cousins, and so on.
If I were to add in
the fact that each of them probably has at least one or two hundred friends and colleagues, we get to a total of 2,000 – 3,000 close contacts in a
group of 13 people. It seems that any
individual has a reasonable chance of knowing someone with the disease,
especially if they know a lot of older people.
So if, anecdotally,
the 1 in 350 adults figure is reasonable, how many people in total have
Parkinson’s?
In the UK the number
is around 130,000 to 140,000.
Across the world, the
average rate of Parkinson’s across all
ages is more like 1 in 700. At the time of writing, the world’s population
is a little over 7.6 billion (see http://www.worldometers.info/watch/world-population/
) so this gives a figure of approximately
10 million people in the world with Parkinson’s, a number which is often
quoted.
However, this is only
part of the story. Parkinson’s is still primarily an old person’s disease and the incidence
of Parkinson’s in different countries depends on the ages of the people in
those countries. An older population means a higher proportion of people with Parkinson’s.
Moreover, countries
like the UK will have ever increasing numbers of old people in the next few
decades. For example, the Office for
National Statistics projects that by 2041 the number of people over the age of
85 will have doubled from 1.6 million today to 3.2 million. This is a result of
both better healthcare and the ageing group of baby-boomers born in the 1960s.
On a global scale, the
Michael J Fox Foundation recently predicted that by 2042, the total worldwide number
of sufferers of Parkinson’s will have doubled from today.
Medical science has
made great strides in beating many forms of cancer and other conditions like
heart disease. In the coming decades, the scientific spotlight will surely now
start focussing on the rapidly increasing prevalence of neurodegenerative
diseases including Parkinson’s and Alzheimer’s.
In the meantime, as
the years rumble on, I can expect several more friends at my annual reunion to start saying they know someone with Parkinson’s.
