The effects of prenatal exposure to nicotine and cannabis on brain
development at school age

Three to 4 percent of the Dutch population is currently using cannabis. This is
9% in younger population (Trimbos, 2003).
This means that there is a large group of women of child-bearing age that are
using cannabis. Cannabinoïds have an influence on the (brain) development of a
fetus. Also, smoking during pregnancy has a clear influence on the (brain)
development of the fetus. Yet, it is unclear what the long-term effects are of
prenatal exposure to cannabis and nicotine on the brain of a young child. We
hypothesise that:
- children with prenatal nicotine exposure to have smaller total brain volumes
than children not exposed to drugs in utero;
- children with prenatal cannabis exposure to have smaller total brain volumes
than children exposed to cigarette smoking or non-drug-exposed children.

What are the long-term consequences of prenatal exposure to cannabis and
nicotine on the brain development of 6-year old children?

This is a non-therapeutic, observational MRI study. Before making the MRI,
there is a practice session with a mock scanner. The practice session is aimed
at reducing possible fear by preparing the child for the MRI. They get
acquainted with the scanner, the scan noises and learn to lay as motionless as
possible during the scans. Furthermore, it is emphasized that the child can end
the scanning procedure by one push on a button. After the practice session, the
following MRI sequences are made; 3D T1 weighted scan, DTI scan and a T2
weighted scan. Furthermore, all children will perform a neuropsychological
testbattery.
We compare 3 groups. The cannabis group is compared to the reference group of
non-exposed children. The nicotine group is compared to the reference group.
The cannabis group is also compared to the nicotine group to study the effects
of cannabis while controlling for the effects of smoking.

There are no known medical risks associated with an MRI. As the study concers
children, there is an extensive practice protocol aimed at making the procedure
as enjoyable as possible. During practising (one session, but more session are
also possible) the child is acquainted with the scanner, the scan room and scan
noises. At multiple moments, the child is asked whether he/she enjoys the
procedure and if he/she is scared. This is a clear opportunity for the child to
(non-verbally) express a desire to stop the procedures. The researcher will
also during the practice procedure and the MRI scan assess continually if the
procedure should be stopped. The procedure will be stopped immediately if the
child, the parents or the researcher wish it so. During the practice session
and during the MRI will the child be able to watch cartoons. There will be
several DVDs for the child to choose from to watch during the MRI and not be
bored.