I__. - International Military Testing Association

-- ---. ----- --- --.._ _ .I-. I
heat (2 mg atropine, 600 mg 2-PAM, 95OF c35°C1. 60% RH). On each
test day, the soldiers received either atropine/2-PAM or
equivalent volumes of saline placebo, injected into the thigh
muscle by 22-gauge syringes. Drug conditions were double-blind;
however, the study medical monitor knew the identities of both
drug and placebo participants. Test days were separated by at
least three days for recovery from the preceding drug conditions.
Daily testing began 30 min after drug administration.
Participants attempted to complete three cycles of the
performance tasks each testing day, and performed until either
they withdrew voluntarily or were removed by the medical monitor-.
Cycles began at standard 2-hr intervals to maintain uniformity of
daily heat exposure. Participants were allowed to drink water ad
lib from standard military canteens; lunch and snacks were
omitted.
Three subjective tests were administered periodically during
each experimental session: (a) the US Army Research Institute of
Environmental Medicine Environmental Symptoms Questionnaire (ESQ;
Kobrick a( Sampson, 1979), as modified by Kobrick, Johnson, and
McMenemy (19881 ; (bl the Profile of Mood States (POMS; McNair,
Lorr, & Droppelman, 19811; and (cl the Brief Subjective Rating
Scale (BSRS; Johnson, 19811. The ESQ is a self-rating inventory
for sampling subjective reactions and medical symptomatology
during exposure to environmental and other stressors. The'POMS
is a rating scale of 65 items to assess 6 mood states (tension,
depression, anger, vigor, fatigue, confusion). The BSRS
appraises subjective feelings of warmth, discomfort, and
tiredness on separate rating scales by selection of descriptive
words or phrases. The ESQ and POMS were given once at the end of
each daily session. The BSRS was given once at the beginning of
each session (30 min post-injection) and once at the end of each
cycle (150, 270 and 390 min post-injection).
Participants performed the following cognitive tasks in each
2-hour testing cycle: (11 verbal reasoning - judging the
correctness of grammatical transformations (Baddeley Grammatical
Reasoning Test, 1968); (2) simple reaction time - pressing a key
to the onset of a signal 1,lght; (3) choice reaction time -
pressing one of two keys to the onset of one of two signal
lights; (4) digit -symbol substitution - substituting code symbols
for their symbol counterparts (Digit Symbol Substitution Test,
Wechsler, 18551; (51 speech intelligibility - correctly
identifying spoken words among other similar words (Modified
Rhyme Test, House, et al, 19651.
Results
The group mean ratings for each of the 68 ESQ items in each
of the four test conditions showed the fewest severe symptoms in
the control condition. The two heat conditions generated more
symptoms, and different patterns of incidence related to heat.
Atropine/2-PAM generated high ratings on symptoms usually
attributed to those drugs (dry mouth, thirst). Drug/heat, the
most severe test condition, generated the greatest number of high
211
_