Background Previous functional neuroimaging studies have shown brain activation abnormalities in clinically presymptomatic carriers of the Huntington's disease (preHD) gene mutation when performing complex cognitive tasks. However, little is known about the neural correlates of basic attentional processes in preHD.
Aims/methods In this study, we used functional MRI to investigate basic aspects of attentional processing in preHD individuals (n=18) compared to healthy participants (n=18) during an alertness task. Uni- and multivariate statistical techniques were used to assess task-related regional brain activation and functional network connectivity.
Results Compared to healthy controls, preHD individuals near to the estimated onset of clinical signs showed lower activation of right frontostriatal regions during phasic alertness (p<0.001, uncorrected). Decreased striatal activation in this preHD subgroup was also evident when compared to those preHD individuals far from the estimated onset of HD signs. Lower putaminal activity was associated with longer reaction times and with proximity to onset. In addition, preHD participants near to onset had lower functional connectivity of motor regions when compared to controls and preHD individuals far from onset.
Conclusions Our data suggest that while alertness-related performance remains normal the underlying frontostriatal activity and motor cortex connectivity decline only when nearing the onset of unequivocal signs of HD. However, these attentional network abnormalities might not be the sole explanation for the differences in cognitive task performance previously observed in preHD.
- Functional MRI
- prefrontal cortex