Accumulating evidence points to a genetic contribution to explain
inter-individual vulnerability to sleep deprivation. A functional polymorphism
in the BDNF gene, which causes a valine (Val) to methionine
(Met) amino acid substitution at Codon 66, has been associated with cognitive
impairment, particularly in populations with impaired frontal functioning. We
hypothesised that sleep deprivation, which affects frontal function, may lead to
cognitive dysfunction in Met allele carriers. To examine this, we investigated,
in different BDNF genotypes, the effects of sleep deprivation
on cognitive flexibility, as measured by response inhibition using the Stroop
Color Naming Task. Thirty healthy, adults of European ancestry, including 12
heterozygous Met allele carriers and 18 Val/Val homozygotes, underwent 30-h of
extended wakefulness under constant routine conditions. A computerised Stroop
task was administered every 2 h. Error rate and reaction times increased with
time awake for all individuals. Participants with the Val/Met genotype made more
errors on incongruent trials after 20 h awake. While Val/Met participants also
took significantly longer to respond when inhibiting a prepotent response
irrespective of time awake, this was particularly evident during the biological
night. Our study shows that carriers of the BDNF Met allele are
more vulnerable to the impact of prolonged wakefulness and the biological night
on a critical component of executive function, as measured by response
inhibition on the Stroop task.