Chronic Exposure to Solvents Disturbs Brain's Wiring

FRIDAY April 18, 2008 -- Long-term exposure to solvents in products such as paints and dry cleaning agents may cause disturbances in the brain's wiring, researchers report.

These abnormalities play a role in a condition called chronic solvent-induced encephalopathy (CSE), the Dutch team conclude in the April issue of the Annals of Neurology.

People with CSE experience problems with memory, attention and psychomotor function long after exposure to solvents has ceased, according to background information in the study. Cases of CSE, a recognized occupational health problem, are increasing in a number of western nations.

This study found that disturbances within the brain's frontal-striatal-thalamic (FST) circuitry are related to the clinical characteristics of CSE, as well as to the severity of exposure to solvents.

The study included 10 CSE patients who'd been exposed to solvents and had mild to severe cognitive impairment, 10 people who'd been exposed to solvents but had no CSE symptoms, and 11 people with no exposure to solvents and no CSE symptoms.

All the participants underwent a number of tests, including MRI and single photon emission computed tomography (SPECT) scans to assess their FST circuitry.

The CSE patients had reduced striatal dopamine D2 receptor (D2R) binding ratios, which were predictive of impaired psychomotor speed and attention, and were also linked to solvent exposure severity, the study authors found. Dopamine receptor density is believed to play a role in psychomotor speed.

The 10 people who were exposed to solvents but had no CSE symptoms showed similar reductions but to a lesser extent. Both groups showed reduced levels of choline (which plays a role in neurotransmission) in the frontal grey matter of the brain.

The results indicate that certain parts of the FST circuitry are affected in CSE patients and in workers who've been exposed to solvents but don't have any CSE symptoms, the study authors said.

"A better understanding of the nature, severity and specificity of these suspected biological markers may further validate diagnostic procedures, this reinforcing medical and social recognition, and underlining the importance of prevention," wrote Ieke Visser, of the Academic Medical Center in Amsterdam, and colleagues.

More information

The U.S. National Library of Medicine has more about CSE.

Posted: April 2008


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