“Frontal” Behaviors Before the Diagnosis of Huntington’s Disease and Their Relationship to Markers of Disease Progression: Evidence of Early Lack of Awareness

Huntington’s disease (HD) has been linked with fronto-subcortical neuropathology and behaviors consistent with this dysfunction. Little is known about these “frontal” behaviors in the earliest phase of the illness. Comparisons between participants in the Predict-HD study (745 “expansion-positive” and 163 “expansion-negative” controls) on the Frontal System Behavioral Scale looked for evidence of frontal behaviors, including apathy, disinhibition, and executive dysfunction. We were also able to compare participant and companion reporting of these frontal behaviors, as a possible indication of awareness of behaviors. Expansion-positive individuals reported significantly more of these frontal behaviors than expansion-negative peers. Self- and companion-reported frontal behaviors were related to other HD markers. Expansion-positive participants closest to HD diagnosis showed greater discrepancies with companions on ratings of frontal behaviors. Even though most are more than 10 years from HD diagnosis, mild frontal behaviors were present in this prediagnosed sample, which might make these behaviors useful as markers for HD onset. Participants/companions discrepancies, especially closest to HD diagnosis, might suggest early lack of awareness in these individuals.