As a parent of a relatively new teenage driver, I have experienced first
hand the anxiety that can be associated with watching your child pull out
of the driveway. For parents whose teen has ADHD this may be especially
anxiety provoking because difficulties with attention and impulsivity can
compromise the ability to drive conservatively and safely. In fact,
research has demonstrated that adolescents with ADHD are 2 to 4 times more
likely to experience motor vehicle accidents, and over three times more likely
than other teens to incur associated injuries.
Research has also shown, however, that medication treatment can improve the
driving performance of teens with ADHD. In one study of this issue,
the simulated driving performance of adolescent and young adult males with
ADHD was significantly worse than matched controls when they had been given
placebo before the test. However, 1 to 1.5 hours after taking medication,
their driving performance improved to the point that it no longer differed
from controls. (The medication tested in this study was immediate release
methylphenidate, which is the generic version of Ritalin).
Although this result demonstrates that medication treatment can improve adolescents'
driving, short acting medications must generally be administered 3 times
per day to achieve full day coverage. Even when this dosing regimen
is followed, however, blood level concentrations wax and wane during the
day, which may be associated with fluctuating levels of symptom management.
During evening hours, as the final dose of medication is wearing off, there
may be a "rebound" of symptoms that could make driving during this time especially
In recent years, an important advance in medication treatment of ADHD has
been the introduction of longer acting preparations (e.g., Concerta, Adderall
XR, Ritalin LA). These medications often provide full day symptom management
with a single dose, and because there is also less fluctuation in blood level
concentrations, may reduce the ebb and flow of symptoms associated with short
acting meds. This suggests that such medications may be even more effective
in promoting safer driving among adolescents with ADHD. This possibility
was examined in a recently published study titled the "Impact of methylphenidate
delivery profiles on driving performance of adolescents with ADHD: A pilot
study" (Cox et al., (2004). Journal of the American Academy of Child and
Adolescent Psychiatry, 43, 269-275).
Participants were 6 males with ADHD; their mean age was 17 and they averaged
15 months of driving experience. Their driving performance was tested
under 2 medication conditions - 3 daily doses of immediate release methylphenidate
and 1 daily dose of Concerta, an extended release version of methylphenidate
that provides up to 12 hours of symptom coverage with a single dose.
In both conditions, a careful titration procedure was used to determine the
optimum dose for each participant.
Two types of driving data were collected. First, participants maintained
a daily driving diary for 7 days on each type of medication. Each day,
they rated how frequently they engaged in 7 risky driving practices, e.g.,
tailgating, on a 0 ("not at all") to 3 ("quite a bit") scale. This
diary provided self-report ratings of risky driving in real-world conditions.
To obtain more precise and controlled information about participants' driving
while on each medication, a laboratory assessment of driving safety using
the Atari Research Driving Simulator was conducted. This is a realistic,
interactive simulator that generates accurate, reliable, sensitive, and valid
driving performance data. The simulator has 3 25-inch computer screens
that wrap around the driver, providing a visual experience comparable to
actual driving. The driving experience is realistic, incorporating
a typically sized steering wheel, gas and brake pedals, seat, and seat belt.
The simulator also provides "drivers" with visual, auditory, and kinesthetic
feedback that is comparable to actual driving conditions.
During the simulated driving test, data is recorded multiple times each second
to generate 9 different driving performance variables. Three of these
variables reflect steering control (driving off the road, veering across
the midline, erratic steering), 4 reflect braking (inappropriate braking
while on open road, missed stop signals, bumps with impact < 5 miles per
hour, and collisions with impact > 5 miles per hour), and 2 reflect speed
control (exceeding the speed limit, and variability of driving speed).
These variables are combined into a single composite score of impaired driving
with higher scores indicating more dangerous driving behavior.
The driving simulator test was completed on 2 separate days, once when participants
received their 3 daily doses of methylphenidate (given at 8 AM, 12 PM and
4 PM) and once when they received a single morning dose of Concerta.
On each day, participants completed a 20-minute simulated drive at 2 PM,
5 PM, 8 PM, and 11 PM so that variability in driving performance during the
day could be examined.
A comparison of participants driving simulator scores during each medication
condition was striking. At the 2 PM and 5 PM assessments, the impaired
driving score was comparable for each medication condition. However, when
participants received regular methylphenidate, there was an enormous increase
in dangerous driving behavior at the 8 PM assessment, and an indication that
their driving continued to worsen between 8 and 11 PM. In the Concerta
condition, in contrast, participants' driving scores showed no such decline
and remained steady across all 4 testing times.
In addition to this difference in the composite score, driving performance
was better in the Concerta than the regular methylphenidate condition for
all 9 variables measured. These differences were most pronounced for
inappropriate braking, percent of missed stop signs, variability in speed,
and collisions with impact > 5 mph.
To put these results in perspective, the researchers evaluated participants
driving performance at the 8 PM assessment in relation to extensive normative
data collected with the driving simulator on over 300 middle-aged and senior
drivers. Participants' driving performance while on Concerta was comparable
to a low-risk group of male drivers aged 50-55. When receiving 3 daily
doses of methylphenidate, however, they performed like a high-risk group
of males aged 80 and above.
Results obtained with the simulator were consistent with participants' daily
driving records, as they rated themselves as engaging in more risky driving
behavior when taking regular methylphenidate then when taking Concerta.
SUMMARY AND IMPLICATIONS
Results from this study clearly indicate that when adolescent drivers with
ADHD were treated with Concerta, they demonstrated less variability and performed
significantly better throughout the day on objective measures of driving
performance than when they were treated with 3 daily doses of immediate release
methylphenidate. Although driving performance was comparable during
afternoon and late afternoon assessments, in the evening, when parents are
often most concerned about their teens' driving, the differences in driving
safety were substantial. When taking Concerta, teens' driving during
evening hours continued to match the performance of low-risk middle-aged males.
When taking methylphenidate, however, their performance declined to a level
comparable to males ages 80 and above.
What is particularly striking about these results is that 3 daily doses of
methylphenidate and 1 morning dose of Concerta should both provide approximately
12 hours of symptom coverage. Therefore, how can the dramatic difference
in evening driving performance be explained? The authors suggest 2
possible explanations. First, they speculate that with Concerta, there may
be less waxing and waning of medication levels during the day, and that this
may result in more stable driving performance.
They also suggest that the sharp decay in driving performance at 8 PM that
was evident with methylphenidate may reflect a rebound phenomenon in which
ADHD symptoms get even stronger than usual as the medication wears off.
This type of rebound effect has been reported clinically and is consistent
with the data from this study. There was no evidence of any such rebound,
however, for Concerta.
Although ADHD is often regarded as a school-based disorder, with poor academic
performance frequently cited as the most serious consequence of undertreatment,
the impact ADHD can have on driving performance is also profound. Results
from this study suggest that when the focus of ADHD treatment is solely on
minimizing symptoms during the school day, it may have potentially dangerous
consequences for after school driving. Thus, when medication treatment
has been determined to be an appropriate treatment for a teenager, consideration
should be given to a treatment approach that may reduce the risk of driving
accidents during evening hours, as well as during the day.
There are limitations to this study that are important to be aware of.
First, adolescent females were not included, and the extent to which similar
results would be found with girls is unknown. Second, only 6 adolescent
males were tested, which is why the authors describe their results as preliminary.
However, it was also the case that every participant drove substantially
better during the evening assessments while receiving Concerta, so it is
likely that the findings are robust. As noted above, this study was
published in the Journal of the American
Academy of Child and Adolescent Psychiatry, which is generally regarded
as the premier journal in child psychiatry. It is certainly unusual
that this journal would publish a study that involved only 6 subjects.
I suspect that the reason the editor published the study is because the magnitude
of the findings were so large that she felt it was important for the field
to know about, even though the sample size was small.
Important - As noted in my introduction to this issue, even
though this study indicates that adolescent males drive more safely when
receiving Concerta than when receiving immediate release methylphenidate,
it cannot be concluded that Concerta is superior to other long acting ADHD
medications, e.g., Adderall XR, Ritalin LA, Strattera, as these compounds
were not tested. It is quite possible that these other medications
would be just as effective as Concerta in promoting better driving by teens
during the evening hours. Results from this study should also not be
used to suggest that all adolescent males with ADHD should receive medication
treatment. The impact of treatment on adolescents' driving is only
one of several considerations when deciding on the most appropriate treatment
for an individual teen, and not all teens will have a positive response to
Other interventions, particularly well-conducted behavior therapy,
have been shown to be effective in managing ADHD symptoms. I am not
aware, however, of studies that have examined whether non-medical interventions
also improve the driving safety of teens with ADHD. Studies of non-medical
interventions to improve driving in teens with ADHD would thus be important
to pursue, especially since not all teens will be helped by medication, some
experience intolerable side effects, and some may be unwilling to take medication
regardless of whether it is helpful. Such work could be quite helpful
to parents as they seek the most effective ways to promote safe driving in
their teenage children who have ADHD.