A study on a variant of the Continuous Performance Test: RANDI

Attention deficit hyperactivity disorder (ADHD) is a child psychiatric disorder
with a prevalence rate of 5%. ADHD is diagnosed on the basis of systematically
collected data from teachers, parents and professionals. However, setting this
diagnosis and evaluating the treatment effect could be supported by different
neuropsychological tests that can record the core symptoms of ADHD by a more
objective measure. The continuous performance task (CPT) is a
neuropsychological instrument, which is able to measure the attention span and
response inhibition of a child. A lot of different versions of the CPT are
developed and used for different age groups. This makes it hard to compare the
results on the level of groups and individuals. A new version of the CPT is
developed, by RMPI De Grote Rivieren in cooperation with a software developer,
and named RANDI. An important advantage of this new version compared to the
existing versions is that all relevant parameters can be adjusted separately by
the researcher, so the test can be adjusted to the age of the child or
adolescent. An important goal for the future is - apart from validating RANDI
as a diagnostic instrument - developing a neurocognitive training to practise
impulse control and selective attention by using the CPT. In order to use this
CPT version as a diagnostic instrument and to develop a trainingprogram,
performance data has to be collected for different age groups in a normative
population (6-11 year old children).

The main aim of this study is to collect normative data on the RANDI for
several age groups.

This is a randomized, single blind study with a cross-over design. 180
participants will be divided into three age groups (6-7 years old, 8-9 years
old, and 10-11 years old). The RANDI is a computer task in which geometrical
figures (square, circle, triangle) are presented on a computer screen. Figures
vary in color (yellow or blue). The participant has the instruction to click
the mouse only when the yellow circle is shown. Two conditions are tested: a
high target rate condition (HTR: 60% targets) and a low target rate condition
(LTR: 20% targets). All children conduct both target rate conditions. Children
are randomly assigned to two situations: 1) first the HTR, second the LTR or 2)
first the LTR task, second the HTR task. The second task is conducted a week
after the first task.

The burden of the study is limited. The RANDI will be performed twice by the
children; this will take about 40 minutes divided over two days. Because of the
short length it is unlikely that participation in the study will disturbe the
school routine. Parents of the children will be asked to fill out three
questionnaires which will take about 15 minutes.