Performance at digital testing in Alzheimer's Disease is predicted by selective disruption of microstructural integrity

White matter microstructural abnormalities are increasingly found to be associated with cognitive impairment in Alzheimers Disease (AD). Here, we investigated the relationship between visual short-term memory (VSTM) performance, measured using a digital cognitive task, and integrity of brain white matter tracts. 52 AD and 60 age-matched healthy controls were recruited from the Oxford Cognitive Disorders Clinic. An established digital VSTM test - the Oxford Memory Task (OMT) - was used to measure several key memory metrics including: Identification Accuracy (percentage of correctly identified items), Target detection (probability of correctly identifying the target) and Misbinding (erroneously localizing an item to the remembered location of another item in memory). TBSS (Tract-Based Spatial Statistics) was then applied to investigate in which regions of the brain microstructural disruption of physiological diffusivity correlated with behavioural performance. A key common area, comprising the left optic radiation, forceps major and middle longitudinal fasciculus (MLF), was associated with performance across several VSTM metrics in patients with AD. In addition, misbinding was linked to the left MLF (part III), left inferior fronto-occipital fasciculus and left vertical occipital fasciculus. Microstructural disruption associated with target detection was additionally associated with superior longitudinal fasciculus, and Identification Accuracy with left superior thalamic radiation in AD. These findings reveal a common shared area of altered diffusivity in AD patients linked to global impairment in VSTM, while distinct types of memory errors are associated with disruption of additional contributions of selective white matter tracts. Key pointsO_LIA key common area, comprising the left optic radiation, forceps major and middle longitudinal fasciculus (MLF), was associated with performance across several visual-short-term memory metrics in patients with Alzheimers Disease (AD). C_LIO_LIAn analogous area on the right was related to identification accuracy performance in healthy individuals. C_LIO_LISpecific visual working memory functions were associated with selective disruption of other white matter tracts, such as the left MLF (part III), inferior fronto-occipital fasciculus, vertical occipital fasciculus, superior longitudinal fasciculus, and superior thalamic radiation in AD. C_LI