2.2. Inclusion and Exclusion Criteria

We included original research papers published before May 2020 that met the following criteria: (1) the study sample was composed of UHR individuals; (2) the diagnosis of UHR was based on one of the structured diagnostic questionnaires (SIPS, CAARMS, BSABS, and BSIP); (3) the neuroimaging technique used was DTI, and at least one of the most commonly used DTI parameters were described: FA, AD, MD, or RD; (4) healthy controls (HC) were included; and (5) the publication was in the English language.

Exclusion criteria were: (1) non-original data (systematic or non-systematic reviews, conference abstracts, case studies, etc.); (2) non-UHR individuals (or studies using a mixed sample of UHR patients and patients with a different diagnosis); (3) exclusive use of a genetic high-risk population; (4) research using questionnaires other than those specified; (5) different neuroimaging techniques (no white matter assessment); (6) the required DTI parameters not having been analyzed; and (7) language other than English.