There is evidence that functional adaptive changes arise at the early stages of the disease as a way of limiting the clinical manifestations of tissue damage. Owing to the scattered existence of the structural abnormalities, the association between lesions and clinical disabilities is not straightforward. So, these behavioral abnormalities are not always perceptible with conventional clinical examination. Additionally, MRI scans are administered for this purpose, yet there is a generally week correlation between the early symptoms of cognitive impairment and the conventional MRI measures of structural damage. Furthermore, these cognitive assessments do not seem to identify emerging cognitive deficits early enough to be effectively intervened.

Functional magnetic resonance imaging (fMRI) is a non-invasive tool that can indirectly capture the underlying and hidden lesions through early detection of degeneration and alteration of brain connectivity. However, current studies have evaluated the result of the resting-state fMRI. Based on researches, certain connectivity characteristics during a task execution may not be apparent in the resting state; thus, the resting-state fMRI does not prove to be as effective as task-based fMRI during which the patient is required to perform a specific task.