Studies to know: further readings
| Author | Nathan Baker |
| Pages | 171-208 |
CHAPTER
13
Studies
to
Know:
Further
Readings
downey
,
luke
a
et
al
.
“
The
Effects
of
Cannabis
and
Alcohol
on
Simulated
Driving:
Influences
of
Dose
and
Experience
”
(2013)
50
Accident
Analysis
and
Prevention
879-86,
online:
dx.doi.org/io.ioi
6/j.aap.2Oi
2.07.016.
This
study
reviews
the
effects
of
cannabis
as
well
as
the
additive
and
syn
ergistic
effects
of
cannabis
and
alcohol
on
the
ability
to
operate
a
motor
vehicle.
It
confirms
that
cannabis
can
impair
the
ability
to
drive.
Of
par
ticular
interest
is
the
finding
that
consumption
of
like
amounts
of
canna
bis
can
lead
to
different
levels
of
THC
in
the
blood
depending
on
outside
factors,
in
this
case
the
consumption
of
alcohol.
This
is
important
to
note
given
the
imposition
of
per
se
limits
since
consumption
of
cannabis
alone
may
lead
to
one
blood
level
whereas
consumption
of
the
same
amount
of
cannabis
mixed
with
alcohol
tends
to
lead
to
a
higher
blood
concentra
tion
as
well
as
a
much
greater
level
of
impairment.
The
study
utilized
double-blind,
placebo-controlled
trials.
It
focussed
on
individuals
aged
between
twenty-one
and
thirty-five
years
old.
It
involved
differing
parameters,
including
no
THC,
low
THC,
and
high
THC
con
sumption
crossed
with
no
alcohol,
low
alcohol
(40
mgs
alcohol/ioo
ml
of
blood
administered,
30
mgs
of
alcohol/ioo
ml
of
blood
present
when
tested)
and
high
alcohol
(60
mgs
alcohol/ioo
ml
of
blood
administered,
50
mgs
of
alcohol/ioo
ml
of
blood
present
when
tested).
A
driving
simula
tor
was
utilized
to
mimic
driving
conditions
and
look
for
driving
impair
ment
and
signalling
impairment.
171
DRUG-IMPAIRED
DRIVING
IN
CANADA
The
study
specifically
deals
with
the
issue
of
whether
a
person
is
a
regular
or
occasional
cannabis
consumer
and
this
variable
’
s
impact
on
impairment
It
noted
that
individuals
who
were
regular
users
of
canna
bis
tended
to
have
a
greater
impairment
than
non-regular
users,
which
was
in
contrast
to
expectations.
As
opposed
to
learning
how
to
drive
after
smoking,
individuals
actually
became
worse
with
experience.
It
is
almost
as
if
individuals
who
do
not
have
experience
with
consumption
of
canna
bis
are
more
careful
in
their
driving
than
those
who
consume
more
often.
This
study
used
a
sample
of
eighty
individuals,
thirty-one
female
and
forty-nine
male.
This
small
sample
size
provides
a
useful
starting
point
but
also
emphasizes
the
need
for
more
studies
of
its
kind
in
order
to
bet
ter
assess
the
impact
of
cannabis
consumption
on
the
ability
to
drive
a
motor
vehicle
safely.
At
page
7
of
the
study
it
states:
“
It
should
also
be
noted
that
the
degree
of
impairment
in
the
overall
driving
and
signalling
measures
was
subtle,
and
that
some
of
the
individual
driving
simulator
variables
were
rela
tively
unaffected
by
the
various
THC/alcohol
conditions.
”
The
conclusion
of
the
study
is
that
consumption
of
cannabis,
espe
cially
when
mixed
with
alcohol
and
even
when
alcohol
consumption
is
at
an
otherwise
“
legal
”
range,
is
a
significant
danger.
However,
it
also
illus
trates
that
many
indicia
or
signs
of
impairment
are
not
affected
negatively
by
cannabis
consumption.
For
example,
collision
risk
was
lowest
for
low
THC
and
alcohol
mix
during
daytime
situations
while
the
highest
collision
risk
was
the
same
mixture
during
nighttime
simulation.
THC
seemed
to
have
an
impact
on
the
ability
of
drivers
to
maintain
their
lane
with
a
much
higher
incidence
but
so
too
was
there
a
positive
correlation
to
THC
con
sumption
without
alcohol
and
the
ability
to
react
to
emergencies
generally.
Clearly,
a
larger
sample
size
will
be
needed
to
draw
better
data.
SILBER,
BEATA
y
et
al
.
“
The
Effect
of
d,l-methamphetamine
on
Simulated
Driving
Performance
”
(2012)
219:4
Psychopharmacology
1081-87,
online:
DOI
10.1007/500213-011-2437-7.
This
study
reviews
the
impact
of
the
use
of
methamphetamine
on
the
ability
to
operate
a
motor
vehicle.
The
study
showed
that
there
was
no
significant
effect
on
the
ability
to
operate
a
motor
vehicle
in
the
simu
lated
driving
environment
by
the
use
of
methamphetamine.
172
Chapter
iy
Studies
to
Know:
Further
Readings
Methamphetamine
is
one
of
the
most
commonly
abused
stimulants
among
drivers.
It
allows
longer
and
sustained
periods
of
driving.
It
is
often
abused
by
professional
commercial
drivers.
It
is
classed
in
the
DRE
program
as
a
CNS
stimulant.
The
study
used
twenty
participants,
equally
ten
of
each
gender,
aged
between
twenty-one
and
twenty-four
years
of
age.
A
double-blind,
placebo-
controlled
design
was
used.
Participants
were
given
a
dose
of
d,l-metham-
phetamine
or
placebo,
then
required
to
use
a
driving
simulator.
Some
indicators
of
impairment
were
more
prevalent
in
those
admin
istered
methamphetamine
while
others
were
not.
For
example,
collision
risk
increased
slightly,
as
did
incorrect
signalling
at
intersections.
How
ever,
reaction
time
was
positively
affected
as
was
the
ability
to
deal
with
advanced
situation
collisions.
The
conclusion
of
the
study
was
that
the
use
of
methamphetamine
did
not
significantly
impair
the
ability
to
operate
a
motor
vehicle.
How
ever,
it
did
show
some
impact,
both
positive
and
negative,
which
could
be
argued
as
affecting
the
ability
to
drive.
The
study
identified
limitations
present
in
the
study.
Particularly
of
concern
is
that
ethical
considerations
prevent
the
dosing
of
participants
in
a
study
beyond
a
certain
limit
As
a
result,
individuals
may
be
impaired
by
a
higher
dose
of
methamphetamine
but
such
studies
cannot
be
undertaken
ethically
at
this
time.
The
problem
this
will
pose
for
prosecutors
is
that
the
lack
of
such
studies
may
reduce
the
ability
to
ground
a
conviction
where
methamphetamine
is
the
only
drug
found
in
the
system
of
the
accused.
Further,
the
small
sample
size
of
participants
limits
the
ability
to
extrapolate
the
data
to
the
general
population.
The
authors
decided
that
while
some
deficits
in
the
ability
to
operate
a
motor
vehicle
were
noted
following
consumption,
such
deficits
were
not
statistically
significant.
porath
-
waller
,
amy
j
&.
D
ouglas
j
beirness
.
“
Simplifying
the
Process
for
Identifying
Drug
Combinations
by
Drug
Recognition
Experts
”
(2010)
11:5
Traffic
Injury
Prevention
453-59.
The
objective
of
the
study
was
“
to
statistically
identify
the
set
of
drug-related
cues
from
Drug
Evaluation
and
Classification
(DEC)
evaluations
that
sig
nificantly
predict
the
categories
of
drugs
used
by
suspected
drug-impaired
drivers
(Abstract).
”
This
study
assessed
the
accuracy
of
DRE
experts
in
173
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