Sarin, Pesticides Lead to Memory Loss

Written by Anthony Hardie, 91outcomes

(91outcomes.blogspot.com) - Families of victims of the 1994 sarin nerve agent subway attack by the Aum terrorist group held a memorial today in recognition of the anniversary of the attack, which took place 15 years ago today, on June 27, 1994.

Even while there was major news coverage of the anniversary events reflecting on the lives that were lost due to the attacks, the lasting effects of sarin exposures continue to affect the survivors.

In a 2001 study involving the survivors of the Aum subway attack, it was clear that even low-dose exposures to sarin led to signficantly declining, long-term memory loss -- one of the most commonly (and repeatedly) reported symptoms among ill Gulf War veterans.

However, despite confirmed exposures of at least 100,000 Gulf War ground troops to low-dose sarin following the Khamisiyah detonation, the federal VA has yet to provide presumptive service-connection for memory loss to the thousands of Gulf War veterans whose disabling memory conditions began in 1991.


Pesticides

Another source of cognitive disability in Gulf War veterans may be linked to the industrial-strength pesticides used by Gulf War troops on their uniforms, skin, and sprayed in work, sleeping, and eating areas.

A 2001 French study found that workers regularly exposed to low-level pesticides experienced decreases in memory, selective attention, verbal fluency, and abstraction.

Again, these are common symptoms among Gulf War veterans with Gulf War illness. And again, despite the recognized high-level pesticide exposures of virtually all Gulf War ground troops, Gulf War veterans suffering from cognitive impairments do not have the benefit of VA presumptive service-connection as should have been enacted nearly two decades ago.

Change is needed -- Soon.


A pair of 2001 articles, summarizing the Japanese subway attack survivors study, and providing an overview of the French pesticide study, follow.

The Tokyo Attacks in Retrospect

Sarin Leads to Memory Loss

Written by Ernie Hood, Environmental Health Perspectives, November 2001.

In the wake of the 11 September 2001 terrorist attacks on New York City and Washington, D.C., the threat posed by chemical and biological weapons has instantaneously evolved from hypothetical nightmare to clear and present danger. Under this new set of circumstances, any addition to the body of scientific knowledge about the health effects of chemical or biological agents is particularly timely. In this month's issue, a group of Japanese researchers led by Yuji Nishiwaki report the results of their investigation into the long-term physical and psychiatric effects of acute poisoning by sarin, a deadly military nerve gas [EHP 109:1169-1173].

Flashback to Tokyo. The 1995 sarin attack on the Tokyo subway killed 12, but exposure to the nerve gas may cause many more to suffer long-term memory effects.

Photo credit: Kyodo News International, Inc.

On 20 March 1995, members of the Aum Shinrikyo religious cult released sarin in the Tokyo subway, using umbrellas to puncture newspaper-wrapped bags of the gas as they left the trains. Twelve people were killed in the incident, and more than 5,500 required emergency medical treatment. Although several studies have looked at the acute clinical manifestations of sarin poisoning, the authors felt there was an urgent need to perform an epidemiologic study of the chronic effects of sublethal exposures to sarin.
The team examined rescue workers and police officers who had been dispatched to the scene and were exposed to sarin in the course of performing their duties--a group of subjects with similar occupational, socioeconomic, and educational backgrounds. The study included 56 exposed subjects from the Tokyo fire and police departments, who were subdivided into high- and low-exposure groups, and 52 nonexposed subjects of similar backgrounds from the same departments. The research was conducted three years after the exposure.
To assess neurobehavioral effects, the investigators administered five tests designed to measure psychomotor function and memory function. A significant causal relationship was discovered between exposure to sarin and memory disturbance. The exposed group performed less well, in a dose-effect manner, than the control group in the digit span memory test. In this test, the subject is asked to memorize a series of digits displayed on a computer screen at 1-second intervals and then enter the digits into the computer in the correct order within 10 seconds. Later, the subject is asked to enter the digits in reverse order. It was this backward digit portion of the test that uncovered significant memory loss in the exposed subjects. Other tests suggested other exposure-related memory effects, but the results were not statistically significant.
Subjects were also given psychometric tests to assess traumatic stress symptoms, in order to examine whether there was any correlation between psychologic stress and chronic physiologic effects. No such correlation was discovered.
The authors conclude that their findings suggest causality between the sarin attack and memory disturbance, although the mechanism behind that disturbance is unclear. They recommend further study of the link between sarin exposure and memory loss.

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Pondering on Pesticides

Long-Term Low Levels Impair Thinking

Written by Tina Adler, Environmental Health Perspectives, August 2001.
As Homer wrote, "Wine can of their wits the wise beguile," but what of the grapes that make the wine--or rather, the pesticides with which they are treated? Isabelle Baldi of the Institut de Santé Publique d'Epidémiologie et de Développement in Bordeaux, France and colleagues went to their local vineyards to measure workers' cognitive well-being and see how it related to the amount of pesticides they had encountered over the years [EHP 109:839-844]. Previous studies had shown that high-dose pesticide poisoning can cause acute human health effects such as motor skill damage, impaired intellectual functioning, and memory loss. In this study, the first to assess long-term neuropsychologic effects of chronic, low-level pesticide exposures in a large sample of workers, Baldi and colleagues found many examples of impaired cognitive functioning among exposed workers.
The team interviewed 917 men and women, aged 43-58, between February 1997 and August 1998. Of the study participants, 528 had been directly exposed to pesticides through mixing or spraying over a mean of 22 years, another 173 had been indirectly exposed by contact with treated plants, and 216 had never been exposed. The pesticides used were primarily fungicides.

Lost in thought among the vines. A study conducted on vineyard workers showed for the first time that long-term low-level exposures to pesticides have measurable effects on cognition.

Photo credit: PhotoDisc

The team administered nine neuropsychologic tests to the workers, including the Mini-Mental Status Examination (which measures different cognitive components), the Wechsler Paired Associates Test of memory, the Benton Visual Retention Test, the Isaacs Set Test (which measures the ability to quickly generate lists of words in different semantic categories), and the Finger Tapping Test (which assesses motor speed). The team controlled for factors that could alter test scores, including educational level, age, sex, alcohol consumption, smoking, environmental exposures, and depressive symptoms.
Workers who were either directly or indirectly exposed performed worse on tests of memory, selective attention, verbal fluency, and abstraction compared with nonexposed workers. On a test of both selective attention and working memory, directly exposed workers were 3.5 times more likely to score low compared with nonexposed subjects. On a similar test of selective attention and mental flexibility, the exposed individuals were 3.1 times more likely to score low. The exposed men and women processed information less quickly than nonexposed colleagues, although performances of exposed workers were similar to those of the nonexposed if the tasks were slowed.
The study participants' symptoms were subclinical and didn't appear to interfere with their work, the team writes, and the participants didn't complain about their cognitive deficits. But they might run into cognitive problems as they age, Baldi notes. "This is why we planned a four-year follow-up of the population [starting in 2001] to assess evolution of performances," she says.
One surprising finding: although large amounts of alcohol are neurotoxic, the workers who drank moderately had better test scores than nondrinkers. Other studies have shown a protective effect of moderate wine consumption on cognitive performance. Baldi can't explain the finding, but notes that among these workers alcohol is considered "a noble product."