Skip to ContentSkip to Navigation
Research Heymans Institute Traffic and Environmental Psychology (Verkeerspsychologie, Omgevingspsychologie)

Drugs & Driving

While the impairing effect of Alcohol on driving is well known, and enforcement of alcohol limits is common, the effects of other (legal and illicit) drugs on road safety are less studied. In particular how other drugs interact with Alcohol, and with each other, and how their use while driving can be appropriately policed is of particular interest.

Relevant projects:

ICADTS III, Effects of long term use of medication on fitness to drive

The International Council on Alcohol, Drugs, and Traffic Safety (ICADTS) classifies the impairing properties of medicinal drugs on driving performance into three categories;

presumed safe (I),

moderate adverse effects (II), and

potentially dangerous (III).

In the Netherlands the percentage of chronic ICADTS III users in the population is estimated to be around 6% for sleeping medication and 10% for antidepressants, and increases with age. However, the classification is largely based on pharmacological studies of brief drug use on healthy subjects. Little is known about the impairing effects on chronic drug users who may develop a tolerance for side effects and thus could be fit to drive. The primary goal the current research is to determine if fitness to drive can be assessed from (1) a highway ride focusing on lane keeping performance, (2) a neurological test battery focusing on perceptual functioning, executive functions, and vigilance, and (3) a driving simulator ride focusing on navigating intersections, merging on the motorway, and lane keeping performance. For this, 120 chronic ICADTSIII drug users will be recruited and compared to a matched control group. The fitness to drive norms may be used to individualise driving advice for patients. This study is performed in cooperation with the universities Maastricht and Utrecht.

Druid logo
Druid logo

DRUID (Driving under the Influence of Drugs, Alcohol and Medicine) deals with the scourge of drink-driving and is going to find answers to questions concerning the use of drugs or medicines that affect people’s ability to drive safely.


Reporter takes alcohol & XTC: Nieuwslicht [in Dutch]:

reporter takes MDMA
reporter takes MDMA

Karel Brookhuis


Janet Veldstra

Karel Brookhuis

Dick De Waard

Joke van Dijken

Last modified:28 July 2022 4.09 p.m.
View this page in: Nederlands