Saccadometry of conditional rules in presymptomatic Huntington's disease.

The promise of new treatments for Huntington's disease (HD) has intensified interest in markers of preclinical onset and progression. Recent research has shown that elementary saccadic tasks may exhibit subtle preclinical abnormalities. Other studies have shown cognitive dysfunction to be a major component of early-HD phenotype.

Oculomotor deficits indicate the progression of Huntington's disease.

The oculomotor deficits associated with Huntington's Disease (HD) are one of the earliest signs of disease onset. They include a marked delay in executing voluntary saccades and a difficulty inhibiting saccades to task-irrelevant stimuli. In addition, HD patients develop a deficit in task-switching, which can be demonstrated by the continued adherence to a rule after it has been recently changed.

White matter connections reflect changes in voluntary-guided saccades in pre-symptomatic Huntington's disease.

Huntington's disease is caused by a known genetic mutation and so potentially can be diagnosed many years before the onset of symptoms. Neuropathological changes have been found in both striatum and frontal cortex in the pre-symptomatic stage. Disruption of cortico-striatal white matter fibre tracts is therefore likely to contribute to the first clinical signs of the disease.