Ieke Visser of the Academic Medical Center in Amsterdam studied 10 chronic solvent-induced encephalopathy patients who had been exposed to solvents and had mild to severe cognitive impairment, 10 participants exposed to solvents but had no chronic solvent-induced encephalopathy symptoms and 11 participants not exposed to solvents and had no symptoms.

Subjects were classified according to the duration and level of exposure, symptoms of acute intoxication and the use of personal protection equipment against the solvents.

The study subjects underwent magnetic resonance imaging and single photon emission computed tomography scans to evaluate various aspects of brain circuitry, as well as numerous neuropsychological tests to assess attention and psychomotor speed -- or action of the mind.

The study, published in the Annals of Neurology, showed that chronic solvent-induced encephalopathy patients had reduced striatal dopamine D2 receptor binding ratios predictive of impaired psychomotor speed and attention. The subjects exposed to solvents, with no symtpoms showed similar reductions, although to a lesser extent, the researchers said.