Individual Differences in Alcohol Effects Among High- and Low-

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Individual Differences in Alcohol Effects
Among High- and Low- Impulsive Sensation
Seekers Kelly, T.H., Robbins, G., Martin, C.A.,
Marczinski, C.A. and Fillmore, M.T. Departments
of Behavioral Science, Psychiatry and Psychology,
University of Kentucky
Abstract Previous studies indicate that high
sensation seekers are at increased vulnerability
to drug abuse in part as a result of enhanced
sensitivity to the reinforcing and other
behavioral effects of drugs. This ongoing study
examines the effects of alcohol in groups of high
and low impulsive sensation-seeking adults
matched on levels of alcohol and drug use.
Fifteen of twenty healthy volunteers scoring in
the top and bottom quartiles of gender-adjusted
population norms on the impulsive-sensation
seeking scale of the Zuckerman-Kuhlman
Personality Questionnaire (6 high- and 9
low-impulsive sensation seekers) completed 7 test
days in which assessments were completed before
(i.e., baseline) and after oral dose
administration at times chosen to equate blood
alcohol levels on the ascending and descending
portions of the blood-alcohol curve. Placebo was
administered on the first test day, during which
data are collected but not analyzed. Each of
three doses (0, 0.45 and 0.65 g/kg) was then
tested under double-blind conditions on 2 days
according to a randomized-block design. Alcohol
impaired performance on psychomotor, impulsivity
and attention tasks, increased heart rate, and
engendered both stimulant- and sedative-like
verbal reports of drug effect. Importantly, the
magnitude of alcohol effects varied as a
function of ascending and descending blood
alcohol levels. High sensation seekers reported
significantly greater reports of sedation on the
Alcohol Sedation-Stimulation Scale and
Light-Headed on the Visual-Analog Scale during
both ascending and descending blood alcohol
levels, suggesting that high sensation seekers
are more sensitive to the acute behavioral
effects of alcohol than low sensation seekers.
Supported by DA-05312 and RR-15592.
Method Subjects Fifteen healthy adults, ages 21
to 30, completed medical screening and gave
written consent prior to participating in
outpatient studies lasting 4.5 hours per day (or
until BAL was lt 0.02 g/dl) for seven days. Six
were classified as High Sensation Seekers, and
nine were classified as Low Sensation Seekers.
All subjects received task training and practice
prior to the study until stable performance was
observed. Sensation-Seeking Status All subjects
completed items from the impulsive
sensation-seeking scale of the Zuckerman-Kuhlman
Personality Questionnaire. Those who scored in
the upper and lower 25 of the population, based
on established norms, were classified as High and
Low Sensation Seekers, respectively. Drug Each
dose of alcohol (0, 0.45, 0.65 g/kg) was
administered on two separate days according to a
randomized block design. An additional placebo
dose was administered on the first study days
during which data were collected but not
analyzed. Doses were administered under
double-blind conditions. Procedure (Table 1)
Daily schedules were constant throughout the
study. Subjects completed 30-minute sessions
before drug administration, 30 minutes following
drug administration, and 75 and 90 minutes
following drug administration of the 0.045 and
0.065 doses, respectively. Each session consisted
of verbal report of drug effects (ARCI, VAS,
ASSS), psychomotor (digit-symbol substitution),
impulsivity (Cued RT), and attention (rapid
information processing) measures. Data Analysis
A mixed-model ANOVA was conducted with one
between- (High vs. Low Sensation Seeking Status)
and two within-group (dose x 3 and time x 3)
factors.
VAS Light-Headed
Rating
Figure 1 Effects of alcohol on visual-analog
scale ratings of Light-Headed as a function of
time (Baseline, Ascending, Descending) following
dose administration for low (left panel) and high
(right panel) sensation seekers. Error bars
represent 1 SEM.
Results Blood Alcohol Levels (BALs, Table
2) Dose-related increases in BALs were observed
during both ascending and descending level
sessions for low and high sensation seekers. No
significant differences in BALs were observed
between low and high sensation-seeking groups,
although means during ascending level were
significantly higher than during descending level
for the 0.45 g/kg dose. Significant Alcohol and
Alcohol x Time Interactions (Table 3) ARCI
Alcohol increased ratings on the PCAG, LSD and A
scales, although effects on the A scale occurred
only during ascending BALs. VAS Alcohol
increased ratings on the Stimulated, Sedated,
Light-Headed, Sick-to-Stomach, High, Feel Drug
and Like Drug scales. ASSS Alcohol increased
ratings on the Stimulated and Sedated composite
scales, with magnitude of effect varying as a
function of ascending and descending
levels. DSST Alcohol decreased total trial rate
and performance accuracy. RIP Alcohol increased
reaction time (i.e., decreased trial rate) and
decreased accuracy, although effects on accuracy
were limited to ascending levels. Cued RT
Alcohol increased reaction time (i.e., decreased
trial rate) and decreased accuracy. Cardiovascular
Alcohol increased heart rate, although effects
were limited to descending levels. Significant
Sensation-Seeking Status x Alcohol x Time
Interactions Figure 1 presents the effects of
alcohol on VAS ratings of Light-Headed separately
for low and high sensation seekers. Significant
alcohol x time interactions were observed for
both low and high sensation seekers, although the
magnitude of drug effect was clearly greater for
high sensation seekers. Significant sensation
seeking status x time interactions were observed
at the 0.45 and 0.65 g/kg dose conditions.
Significant sensation-seeking x alcohol dose
interactions occurred during both ascending and
descending level sessions, although the magnitude
of the interaction was clearly greater during
ascending level sessions. Figure 2 presents the
effects of alcohol on the ASSS composite Sedated
scale separately for low and high sensation
seekers. Significant alcohol x time interactions
were observed for both low and high sensation
seekers, although the magnitude of drug effect
was clearly greater for high sensation seekers.
Significant sensation seeking status x time
interactions were observed at all dose
conditions. Significant sensation-seeking x
alcohol dose interactions occurred during both
ascending and descending level sessions.
Significant sensation-seeking status x dose x
time interactions were also obtained on VAS
ratings of Stressed and Anxious (data not shown).
For VAS Stressed, significant alcohol x time
interactions were observed for both low and high
sensation seekers significant sensation seeking
status x time interactions were observed at the
0.45 and 0.65 g/kg dose conditions, and
significant sensation-seeking x alcohol dose
interactions occurred during both baseline and
descending level sessions, with alcohol effects
being greater among low sensation seekers. For
VAS Anxious, significant alcohol x time
interactions were observed for both low and high
sensation seekers significant sensation seeking
status x time interactions were observed at at
the 0.45 and 0.65 g/kg dose conditions, and
significant sensation-seeking x alcohol dose
interactions occurred during baseline, ascending
and descending level sessions, with alcohol
effects being greater among low sensation
seekers. No group differences in drug use or
other psychiatric symptoms, including conduct
disorder, ADHD, depression or scores on the BSI,
were observed.
ASSS Sedation
Table 1 Daily Schedule Time
(Min) Event 00 Intake Assessment Baseline
Session Dose Administration 30 Ascending
Session 75/90 Descending Session Discharge
Assessment Session Tasks Addiction Research
Center Inventory (ARCI) The 49-item short form
of the true-false ARCI provided reports of drug
effects on five scales LSD, Amphetamine (A),
Benzedrine (BG), Morphine-Benzedrine (MBG) and
Pentobarbital, Chlorpromazine, Alcohol Group
(PCAG). Visual-Analog Rating Scales (VAS)
Ratings of Stimulated, Sedated, Light-Headed,
Drug Effect and Like Effect were obtained by
placing marks on a 100-unit line anchored with
"Not at all" on the left and "Extremely" on the
right. Alcohol Sedation-Stimulation Scale
(ASSS) Composite scores for Sedation and
Stimulation were obtained by summation of ratings
from 14 adjectives on a scale from 0 to 10 with 0
being Not at all and 10 being
Extremely Digit-Symbol Substitution Task (2
minutes) Nine random 3-row by 3-column arrays of
asterisks and dashes (one asterisk per row),
labeled 1-9 from left to right, were displayed at
the top of the computer monitor. A randomly
generated number, between 1 and 9, was displayed
in the center of the monitor, indicating which of
the nine arrays should be reproduced on a given
trial. Subjects reproduced an array by pressing
the buttons on a 3-row by 3-column keypad that
corresponded to the positions of the asterisks in
the screen array. Rapid Information Processing
Task (RIP, 5 minutes) Single digits were
presented in the center of the monitor, and
subjects were instructed to press a key whenever
three consecutive even or odd digits were
presented. Following correct responses, the
speed of digit presentation was increased, and
following incorrect responses or missed signals,
the speed of digit presentation was decreased.
Cued Reaction Time (Cued RT, 15 minutes)
Subjects are required to respond as quickly as
possible when green rectangles are presented on
the screen, and to make no response when blue
rectangles are presented. Horizontal and
vertical white rectangles predicting the
subsequent color presentation on 60 of trials
were presented prior to the color
cue. Cardiovascular Heart rate and blood
pressure were recorded immediately after
completing computer tasks.
Score
Figure 2 Effects of alcohol on the ASSS
composite Sedated scale as a function of time
(Baseline, Ascending, Descending) following dose
administration for low (left panel) and high
(right panel) sensation seekers. Error bars
represent 1 SEM.
Conclusions 1. The effects of alcohol on subject
report measures of drug effect were consistent
with the results of previous studies. Typical
stimulant- and sedative-like effects were
observed on ARCI, VAS and ASSS scales.
Dose-related increases were observed on several
scales that have been associated with the
reinforcing effects of drugs (i.e., VAS Like
Drug ARCI PCAG and A scales ASSS Stimulated and
Sedated scales). 2. High sensation-seekers
exhibited greater sensitivity to the effects of
alcohol on VAS ratings of Light-Headed and the
ASSS composite Sedated scale. Group differences
in drug effects were observed on other scales, as
well, but effects did not reach statistical
significance. To the extent that these measures
are associated with the reinforcing effects of
alcohol, the data suggest that the reinforcing
effects of alcohol may be greater in high
sensation seekers than in low sensation seekers.
3. The effects of alcohol on measures of task
performance were also consistent with the results
of previous studies. Typical sedative-like
effects were observed on DSST, RIP and Cued RT
task performance. Differences in impairment as a
function of ascending and descending alcohol
levels varied across tasks. 4. The effects of
alcohol on several subject report, cardiovascular
and task performance measures varied as a
function of ascending and descending alcohol
levels, suggesting that the functional effects of
alcohol vary as a function of relative changes in
BAL. 5. High sensation seekers are more likely
than low sensation seekers to engage in a variety
of high-risk behaviors, including drug use.
These data suggest that while high
sensation-seekers may be more likely to initiate
experimentation with drug use, they may also be
more vulnerable to the reinforcing effects of
alcohol, and thereby be at greater risk for
developing repeated patterns of drug-seeking
behavior.