Pesticides and dementia risk: Do you wash your fruit before eating it?

It probably wouldn’t come as any great surprise that people who have to work in close contact with pesticides might suffer some unpleasant ill health side effects. After all, pesticides are strong chemicals designed to kill pests, which would otherwise damage the crop being grown.

A recent study published in Occupational and Environmental Medicine has suggested that long-term exposure to pesticides may be linked to the development of dementia.

The researchers were looking to see what the impact of long term pesticide exposure was on cognitive abilities on people in their 40’s and 50’s. These were people who had all spent at least 20 years working in the agricultural sector.

614 vineyard workers in South West France had their intellectual capacity monitored as part of the PHYTONER study spanning a six year period.

The level of pesticide exposure was divided into 3 groups

Direct exposure through mixing or applying pesticides, or contact with cleaning or spraying equipment. • Indirect exposure from contact with treated plants and possible indirect exposure from working in cellars and associated office buildings. • No exposure ie they had not worked in any of the above areas.

The 614 subjects were monitored between 2001 and 2003. They were each asked to complete a questionnaire and complete nine neuro-behavioural tests designed to measure memory and recall, language retrieval and verbal skills and reaction time speeds. Half of the group were in the direct exposure category, 20% had had no exposure and 30% had had indirect exposure.

Lower scores were found in the older workers, those with a lower level of education, excessive alcohol intake, depression or drug use which was no unexpected.

However it was also shown that in seven out of nine tests, those who had been exposed to pesticides performed significantly worse on the second testing at the end of just two years.

This group were up to x5 more likely to have scored lower in both tests and x2 as likely to register a drop of two points in the mini mental state exam (MMSE) This is a test frequently used by General Practitioners to determine if a person has dementia. It is a brief 30 point test. A score of 25 or more out of thirty is considered normal. A score of 20 to 24 indicates mild cognitive impairment.

A two point loss in this group over such a short time frame is of concern and especially as this was in a group of 40 and 50 year olds. Previous studies have indicated that exposure to pesticides is associated with poor mental performance.

This demonstration of mild impairment of cognition or thinking skills is a worry as it suggests that this group of people are at higher risk of developing neurodegenerative disease such as Alzheimer’s and other dementias.

For baby boomers and others, considering moving to that idyllic lifestyle of perhaps owning and running your own vineyard, there may be a higher cost to pay. Certainly food (or should that be pesticide?) for thought.

Baldi, A. Gruber, V. Rondeau, P. Lebailly, P. Brochard, C. Fabrigoule. Neurobehavioral effects of long-term exposure to pesticides: results from the 4-year follow-up of the PHYTONER Study. Occupational and Environmental Medicine, 2010; DOI: 10.1136/oem.2009.047811