Michael J. Fox and the Parkinson’s cluster

Here is another unusual disease cluster. Michael J. Fox most likely contracted Parkinson’s disease in the late 1970s while working on a TV series in his native Canada. Intriguingly, 4 other members of the crew also contracted Parkinson’s.

According to this NY Times article, Parkinson’s ’Clusters’ Getting a Closer Look:

The four people worked together from 1976 to 1980, when it is possible that the disease began in all of them.

Probability about 1 in 1,000

After studying the cluster:

Dr. Donald Calne, director of the neurodegenerative disorders center at the University of British Columbia, estimates that the odds of the four cases occurring at the same time in such a small group of people are less than 1 in 1,000.

Some of the reasoning behind this conclusion:

Typically, Parkinson’s disease afflicts one in 300 people. In people as young as Michael J. Fox, 30 when the disease was diagnosed in 1991, the illness is much rarer. Fewer than 5 percent of Parkinson’s patients develop symptoms before age 50, said Dr. Caroline Tanner of the Parkinson’s Institute. The Vancouver cluster includes Mr. Fox and a woman who learned she had Parkinson’s at age 38.

[...] Parkinson’s progresses gradually, taking 5 to 10 years from the time it starts to the appearance of the first symptoms -- usually, rigidity in an arm or leg or tremor in a hand.

A Possible Cause

There is speculation that some environmental agent was the cause of this cluster. One possibility is a drug, since:

There are three classes of drugs that are likely to produce Parkinsonism:

1. Dopamine receptor blocking agents, including the phenothiazines (such as Compazine, Stelazine, and Thorazine), butyrophenones (such as Haldol), and metoclopramide (Reglan).
2. Dopamine-depleting agents, including reserpine (rarely used) and tetrabenazine (used to control dyskinesia)
3. Drugs that act by various known and unknown mechanisms, including the atypical antipsychotic drugs such as Resperidal, Orap, and Zyprexa). (Source: PDcaregiver.)

There have been cases of drug addicts who have taken a badly ’cooked’ dose and have had Parkinson’s-like symptoms.

Other environmental factors in Parkinson’s include weedkillers and pesticides (from MSNBC, no longer available):

One study shows that farm workers who used the common weedkiller Paraquat had two to three times the normal risk of Parkinson’s, a degenerative brain disease that eventually paralyzes patients.

Connection with the ABC Breast Cancer Cluster

This story reminds me of the breast cancer cluster in the ABC television studios in Brisbane Australia, which I wrote about recently. In that case, the probability of the cluster was estimated to be 1 in a million, but I have not been able to find out how that probability was reached.

Higher Risk of Parkison’s

Something that worries me is that those at higher risk of contracting Parkinson’s Disease are teachers (that’s me) and medical workers. Other high risk occupations include farm workers, loggers and miners.

Footnote

Curiously, in one trial, Gambling and sex addiction caused by Parkinson’s drug, we read:

Apparently after taking the drugs, called dopamine agonists, some patients have developed gambling habits so severe, that some of them lost more than £100,000 in six months,while others developed behavioural problems, including compulsive eating, increased alcohol consumption, and an insatiable appetite for sex.

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