Does being a life-long vegetarian improve your intelligence?

As an omnivore, my gut feeling is that it doesn't. But it might. The 1970 British cohort study followed 17,198 people born in April 1970. Their IQs were measured when they were 10. The vegetarians (including some who occasionally ate fish or chicken) had a higher average childhood IQ than the non-vegetarians. The question is: do more intelligent people choose to be vegetarians, or does being a vegetarian make you more intelligent? At 30 the remaining people in the study (now only 8,170) had a higher average IQ than the average of the larger group when they were 10. Some of the 30-year-olds only became vegetarians as teenagers. As most were in higher education and graduated to non-manual jobs, their vegetarianism may have been only one of many lifestyle choices linked to education, rather than a cause of higher intellect. So the jury is out.

Is there a connection between Parkinson's disease and an obsession with gambling? My husband has got into betting since he was given the diagnosis. He doesn't seem to be able to stop.

It may not be the disease but the treatment. In a study of 400 people being treated for Parkinson's, 8% became problem gamblers - 25 times more than expected. It's proposed that the treatment, drugs called dopamine agonists, may have something to do with the change in personality. Yet the drugs are very effective in easing the symptoms of the illness.

· Do you have any questions for Dr Smith? Email doctordoctor@theguardian.com