From Featuring Dr Chris Steele MBE

Pesticides linked to dementia

Long-term exposure risky, study finds

Long term exposure to pesticides may be linked to the development of Alzheimer's disease and other types of dementia, according to new research.

French researchers monitored the intellectual abilities of more than 600 vineyard workers for six years. All were in their 40s and 50s and had worked in agriculture for at least 20 years.

At the start and end of the study, all completed detailed questionnaires about their work history and underwent nine "neuro-behavioural" tests designed to measure memory and recall; language retrieval and verbal skills; and reaction time speeds.

One in five had never been exposed to pesticides as part of their job; over half had been directly exposed, and the remainder had been possibly or certainly indirectly exposed.

The workers who had been exposed to pesticides were the most likely to perform worse in the neuro-behavioural tests at the end of the six year period.

They were also up to five times as likely to obtain lower scores on both sets of test, and were twice as likely to drop two points in a mini mental state exam (MMSE) - a test often used to determine if someone has dementia.

The researchers said the lower MMSE scores were "particularly striking in view of the short duration of follow up and the relatively young age of the participants."

"The mild impairment we observed raises the question of the potentially higher risks of injury in this population and also of the possible evolution towards neuro-degenerative diseases such as Alzheimer's disease or other dementias," the researchers said.

Dr Anne Corbett, research communications manager at the Alzheimer's Society, said: "This is a relatively small study carried out over a short period of time so we must be careful not to read too much into the results.

"We don’t for example know if the cognitive decline is definitely caused by the pesticides or by other unidentified risk factors that could be common to this group. It is also a step too far to say this decline would lead to dementia.

"One in three people over 65 will die with dementia. Much more research is needed to build on this latest study and to move us closer to establishing the causes and finding a cure for this devastating condition."

The findings are published online in Occupational and Environmental Medicine.

This article was published on Thu 2 December 2010