Spearman’s nonparametric correlations for clinical variables and PC loadings. Notes: Text in bold- italics indicates statistically significant relationship; PC = principal component; MoCA = Montreal Cognitive Assessment; Rey-O = Rey-Osterrieth Complex Figure test; BNT = Boston Naming Test, short form; FAB = Frontal Assessment Battery; FBI = Frontal Behavioural Inventory; MDS-UPDRS III = the Movement Disorders Society-sponsored version of the Unified Parkinson’s Disease Rating Scale, motor subsection; TMT B = Trail Making Test B; TT = Token Test. PiB = global Pittsburgh Compound B (PiB) ratio; WAB AQ = Western Aphasia Battery Aphasia Quotient; PPTT = The Pyramids and Palm Trees Test; NPI-Q = Neuropsychiatric Inventory Questionnaire; TMT A= Trail Making Test; AVLT = Auditory Verbal Learning Test; ST = Short-term retention; LT = Long-term retention.