Question: What has be the most interesting or worthwhile discovery you have made during your research??

Andy MacLeod answered on 21 Jun 2011:

Hello megan. At the moment, the main project I’m working on is looking at the genes that affect how people think, and how that ability declines as people get older.

We have about 1,000 volunteers who were born in 1936, and took an IQ test at age 11 in 1947. My colleagues tracked them down, and gave them similar tests at age 70 in 2006, and they’re coming back every few years so we can follow their progress.

I’m looking at genes that vary in number between people. Mostly we have two copies of every gene, one from mum and one from dad. But sometimes the copying mechanism doesn’t work properly so people might end up with 0 or 1 copies, or with 3 or more. If this happens in a gene that affects intelligence, then we should be able to find a relationship between the number of genes of a specific type people carry, and their intelligence test scores.

I’ve been doing this for a bunch of genes in our sample – for each gene, I count up the number of copies each person has, and compare that to the test scores. Most genes I’ve looked at don’t seem to have much of an effect, but there are a couple that look like they might have. Interestingly enough, these two genes have also been found to affect schizophrenia and autism. If it is a true link, this might help to explain why people with these disorders have lower than average intelligence. I think that’s pretty exciting.

If these genes hold up to further analysis, we can use them to try and work out what’s going wrong when people lose their thinking ability over time. That’s the first step towards developing a treatment to stopping that happening.