D. Storzbach et al., Neurobehavioral deficits in Persian Gulf veterans: Additional evidence from a population-based study, ENVIR RES, 85(1), 2001, pp. 1-13
Reports of low-concentration nerve gas exposures during the Gulf War (GW) h
ave spurred concern about possible health consequences and symptoms reporte
d by many returning veterans. The Portland Environmental Hazards Research C
enter is studying veterans from the northwest United States who report pers
istent, unexplained "Gulf War" symptoms (cases) and those who do not report
those symptoms (controls), An epidemiological survey focused on exposures
and symptoms was mailed to a random sample of GW veterans from Oregon and s
outhwestern Washington. Volunteers recruited from survey respondents agreed
to undergo a thorough medical examination and psychological and neurobehav
ioral assessment. Persistent symptoms with no medical explanation associate
d with Persian Gulf service (e.g., fatigue, muscle pain, memory deficits) b
eginning during or after the war qualified respondents as cases. The 239 ca
ses with unexplained symptoms and the 112 controls without symptoms were ad
ministered a computerized assessment battery of 12 psychosocial and 6 neuro
behavioral tests. Replicating and extending previous interim findings, a su
bgroup of veterans emerged from the initial analysis in the form of extreme
outliers which produced a visually and quantitatively obvious bimodal dist
ribution. This led, as it had previously, to analyses of the outliers as a
separate group (labeled "slow ODTP"), which confirmed the initial findings
of neurobehavioral differences between the outliers and the other cases and
controls and provided more convincing evidence that the majority of cases
who report neurobehavioral symptoms have no objective evidence of neurobeha
vioral deficits. However, the larger group of symptomatic veterans do have
highly significant and compelling evidence of psychological distress based
on scores from 11 separate psychological tests. Whereas the cases differed
from the controls by poorer neurobehavioral test performance, extraction of
the slow ODTP participants (almost all cases) eliminated neurobehavioral p
erformance differences between the remaining cases and the controls and pro
vided support for the hypothesis that the slow ODTP cases might have been f
rom the unhealthy end of the GW population prior to the war. However, there
was no evidence of poor motivation, pre-GW educational differences, or gre
ater association with abnormal psychological function in this group than in
other cases or controls. (C) 2000 Academic Press.