Alterations in heart rate & pupillary response in persons with organic solvent exposure

Cardiac and pupillary reactivity were examined in 25 persons
with a history of exposure to organic solvents and 19
nonexposed controls during performance of a counting and a
choice reaction task. The solvent-exposed group demonstrated
an atypical pattern of responding across tasks. While control
subjects showed a decline in heart rate across the two
conditions (e.g., habituation), exposed persons had an
increase in heart rate. Initial pupil diameter was similar for
both groups, but only the control subjects exhibited
habituation across the two tasks. In the exposed group, higher
heart rate was not associated with higher levels of
self-reported anxiety. Anticipatory cardiac deceleration
preceding unpredictable events was significantly less in the
exposed group, but there were no significant group differences
on poststimulus acceleration. The results suggest that persons
with solvent exposure have a deficiency in the allocation of
attention (reduced anticipatory deceleration and decreased
pupillary dilation). It is further suggested that difficulty
in the allocation of attention produces an increase in tonic
sympathetic levels when confronted with a cognitively
challenging task. In this experiment, in which the choice
reaction task was purposely presented last, and was apparently
more challenging for exposed persons, a failure to exhibit
autonomic habituation over the course of the session
characterized the solvent-exposed group.

Morrow LA, Steinhauer SR

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