Eye Tracking as a Tool for Detecting Alzheimer's Disease in People With Down Syndrome.

Background: Adults with Down syndrome (DS) experience an increased risk of Alzheimer's disease (AD). Valid cognitive assessments for adults with DS with severe/profound intellectual disability (ID) are needed. It is unclear whether eye tracking is feasible for detecting AD in DS.

Method: Fifty-three adults with DS completed a visual paired comparison (VPC) task, a battery of cognitive measures, and underwent PET scanning. Study partners reported on the participant's dementia symptoms. Bivariate correlations assessed associations between eye-tracking metrics and AD-related pathology and symptomatology. Analyses included the full sample (n = 53) and a subgroup with an IQ ≤ 45 (n = 33).

Results: Greater fixation duration during the habituation phase was associated with better cognitive performance on the Modified Cued Recall Test (mCRT) (intrusions: r = -0.39, p = 0.011) and less PET tau (r = -0.47, p = 0.014). Larger saccadic amplitudes during the test phase were associated with younger age (r = -0.45, p < 0.001), better cognitive performance on the mCRT (total: r = 0.31, p = 0.041; intrusions: r = -0.33, p = 0.032) and less PET Aβ (r = -0.40, p = 0.025). Greater preference to fixate on the novel image was associated with fewer dementia symptoms (count: r = -0.44, p = 0.002; duration: r = -0.38, p = 0.009). This pattern of significance remained for the subgroup with lower IQ scores.

Conclusion: The VPC task is a potentially useful method for assessing AD-related cognitive impairments in adults with DS across varying ID levels.