Huntington's disease (HD) is characterized by executive dysfunctions like problems with planning, accuracy, inhibition and impulsivity. During the course of the disease executive function worsens with ongoing pathological changes in the basal ganglia. However, it is not clear whether cognitive dysfunction develops gradually or not during the course of the disease.

We assessed the development of executive dysfunction in 23 patients with early HD and 29 patients with late HD on the Tower of London (ToL) for the number of solved problems, planning time and number of breaks.

HD patients showed a linear decrease of accuracy (as assessed by number of solved problems) during the course of the disease. Controls scored significantly higher than early stage HD patients and early stage HD patients scored significantly higher than late stage HD patients. In planning time and number of breaks a non-linear decrease was found.

Executive dysfunctions in HD are not alone connected to degenerative changes in the striatum as they do not develop gradually and linear during the course of the disease. Obviously, executive function could not be seen as a single component, but as a combination of different abilities, which show a non-linear and non-parallel decline.

The authors have not supplied their declaration of competing interest.