• © International Association for Cannabis as Medicine   1   
• Case report
• Cannabis improves symptoms of ADHD

Peter Strohbeck-Kuehner, Gisela Skopp, Rainer Mattern

Institute of Legal- and Traffic Medicine, Heidelberg University Medical Centre, Voss Str. 2, D-69115 Heidelberg, Germany

Abstract

Attention-deficit/hyperactivity disorder (ADHD) is characterized by attention deficits and an al-

tered activation level. The purpose of this case investigation was to highlight that people with

ADHD can benefit in some cases from the consumption of THC. A 28-year old male, who showed

improper behaviour and appeared to be very maladjusted and inattentive while sober, appeared to

be completely inconspicuous while having a very high blood plasma level of delta-9-

tetrahydrocannabinol (THC). Performance tests,  which were conducted with the test batteries

ART2020 and TAP provided sufficient and partly over-averaged results in driving related per-

formance. Thus, it has to be considered, that in the case of ADHD, THC can have atypical effects

and can even lead to an enhanced driving related performance. 

Keywords: ADHD, cannabis, performance, driving

This article can be downloaded, printed and distributed freely for any non-commercial purposes, provided the original work is prop-

erly cited (see copyright info below). Available online at www.cannabis-med.org

Author's address: Peter Strohbeck-Kuehner, peter.strohbeck@med.uni-heidelberg.de 

Introduction

Assessing the performance or impairment of cannabis

users is generally problematic as there is no stringent

proof of a linear dose-effect relationship between the

concentration of delta-9-tetrahydrocannabinol (THC)

in blood and THC-induced impairment. The cause of

the absence of such a relationship has not been identi-

fied. In this context it is rarely considered that the miss-

ing correlation may be due in part to a conceivable

positive effect of cannabis on the behaviour and per-

formance of individuals. Recently, Adriani et al. [1]

gave evidence that cannabinoid agonists reduce hyper-

activity in a spontaneously hypertensive rat strain,

which is regarded as a validated animal model for at-

tention deficiency hyperactivity disorder (ADHD).

There was also a significantly better treatment retention

of cocaine dependent patients with comorbid ADHD

among moderate users of cannabis compared to ab-

stainers or heavy users [2].

ADHD was long considered a disorder limited to chil-

dren and adolescents. It has now been proven that

ADHD symptoms may persist into adulthood [3,4].

Individuals suffering from  ADHD characteristically

have an increased drive to move around and are unable

to calm down. They are lacking in directed planning of

their actions and the ability to assess the impact of their

decisions. Their ability to organize day-to-day activi-

ties is reduced, they usually have a poor short-term

memory, are forgetful and tend to work in a chaotic

and inefficient way. Emotionally, they are prone to

impulsive outburst, excessiveness and instability [5,6]. 

This present case study describes a male, 28 years of

age, who was diagnosed with attention deficit hyperac-

tivity disorder (ADHD), and whose response to THC

suggests that such a positive effect may exist. Consid-

ering that the subject applied for the reinstallation of

his driving licence gives particular significance to psy-

cho-physical performance deficits caused by ADHD.

Numerous studies have shown that various perform-

ance functions, such as divided attention, selective

attention, long-term attention and vigilance are im-

paired [7].

Case Description

The subject had a record of several violations of the

German drug control law. He also had a record of nu-

merous violations of traffic laws, including speeding,

running of a red traffic light and driving under the

influence of cannabis during which a high THC con-

centration in blood had been detected. 

Seven years ago, the subject had been diagnosed with

ADHD (ICD 10 F90.0) for the first time, and that diag-

nosis had been assessed repeatedly and independently

since by several psychiatric units. There was some Case report

2  Cannabinoids Œ Vol 3, No 1 Œ March 2, 2008    

evidence from his carrier that typical symptoms were

already present in childhood, they were, however, not

properly recorded. Comorbidities such as addiction,

including cannabis, or personality disorders were ab-

sent. He had been treated over a period of about 12

months through a combination of methylphenidate

(Ritalin®, 20-30 milligram/day) and behaviour ther-

apy. Being not sufficiently efficacious, the medication

was stopped. A subsequent certificate by a specialist

for general medicine suggests that ADHD symptoms

were much improved under cannabis and that dronabi-

nol (THC) had been prescribed, even though ADHD is

not indicated for this drug.

Prior to the first contact the subject had been advised

not to consume any medicinal or recreational drug.

During that first visit he showed grossly conspicuous

behaviour. His attitude was pushy, demanding and

lacking distance. He expressed impatience, for example

by drumming his fingers on the table. He also con-

stantly shifted position, folded arms behind his head or

leaned over the table in front of him. He was not open

to discussing the potential impairment of driving skills

caused by cannabis consumption. As the conversation

continued and he was informed of the preconditions for

a positive assessment of his suitability to operate a

vehicle, his behaviour became even more conspicuous

and aggressive. Finally, he got up, grabbed the table,

leaned forward and shouted  that he needed a driving

license and that he needed cannabis. Overall he showed

behaviour typical of persons who suffer from ADHD.

During this visit, an appropriate performance of the

tests was impossible.

He was then offered to undergo, at a later time, a test of

the impact of dronabinol on performance. During this

appointment he appeared fundamentally changed and

was not disturbed at all. He stated that he had stopped

smoking cannabis, was taking dronabinol on a regular

basis and that he had consumed it just two hours ago.

He appeared calm, but not sedated, organized and re-

strained. Unlike during the first meeting he was able to

accept and discuss arguments. When trying to make

clear that THC was indispensable for his quality of life

he became more engaged but without losing restraint.

Rather, he was understanding of the position of the

expert and indicated that the path to get back his driver

license may be long but that he was willing to under-

take it. His behaviour, motor function, mood and con-

sciousness did not give any indications of a prior use of

a psychoactive substance.

The tests of performance functions that are relevant to

driving skills involved the four subtests of ART2020, a

computer-controlled test system, which is commonly

used to assess driving performance. These subtests

evaluate complex reactions (RST3), sustained attention

(Q1), directed attention (LL3) and visual surveying and

perception (TT15). In addition the functions of “vigi-

lance” and “divided attention” were tested with the

attention test module (TAP).

The results of these tests (see Fig. 1) showed that the

subject met, in all of the functions tested by ART2020,

not only minimum criteria but that he achieved average

or, in some areas, even above-average results. In the

very demanding tests for “vigilance” and “divided

attention” categories he also showed average perfor-

mance. ADHD or acute effects of THC by themselves

would usually impair performance particularly in these

tests.

A blood sample was taken after completion of the tests.

It showed a very high concentration of THC (71 ng/mL

serum), of the psychoactive metabolite 11-hydroxy-0-10-20-30-40

RST3 Q1 LL5 TT15 Vigil. Div. Att.

Performance

Criteria

Figure 1: Subjects actual performance and minimum criteria. Strohbeck-Kuehner

Cannabinoids Œ Vol 3, No 1 Œ March 2, 2008  3    

THC (30 ng/mL serum) and of the main non-

psychoactive metabolite 11-nor-delta-9-carboxy-THC

(251 ng/mL serum). Such levels indicate recent as well

as frequent consumption of THC-containing matters,

and the analyte pattern also suggests smoking. Detec-

tion of cannabinol in hair (5.3 ng/mg) along with THC

(3 ng/mg) gives evidence that the medication could not

have been the only source of the THC.

Only much later did the subject, who had been arrested

for a drug offence a few days after the second visit,

report that he had not consumed pharmaceutical dron-

abinol products but instead smoked cannabis just be-

fore the tests, since it was much less costly.

Conclusions

The present case report suggests that individuals suffer-

ing from ADHD, a dysfunction with a symptomatic

change in activity levels, may - in some cases - benefit

from cannabis treatment in that it appears to regulate

activation to a level which may be considered optimum

for performance. There was evidence, that the con-

sumption of cannabis had a positive impact on per-

formance, behaviour and mental state of the subject.

The present observation corroborates previous data of

Müller-Vahl et al. [8] suggesting that in patients suffer-

ing from Tourette syndrome, treatment with THC

causes no cognitive defects. Gilles de la Tourette syn-

drome is a neurobehavioral  disorder associated with

motor and vocal tics as well as behavioural and cogni-

tive problems. The authors also hypothesized that the

effects of cannabinoids in patients may be different

from those in healthy users suggesting an involvement

of the central cannabinoid receptor systems in the pa-

thology of the disorder. The same conclusion may be

drawn from previous studies [1, 2] and the present case

report, although more information on these atypical

effects should be provided and the underlying mecha-

nisms are still to be elucidated. 

References 

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Laviola G. The spontaneously hypertensive- rat

as an animal model of ADHD: evidence for im-

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The complete case-report was published in 2007 in

Archiv fuer Kriminologie 220: 11-19.