Error bars in the figures represent the standard error. Asterisk (*), cross-sign (×), and plus-sign (+) indicate that aMCI-LLD group is significantly different from CN, LLD and aMCI groups, respectively. Filled triangle (▲) and circle (●) indicate that LLD and aMCI groups differ significantly from the CN group. Abbreviations: CN, cognitively normal; LLD, late-life depression; aMCI, amnestic mild cognitive impairment; aMCI-LLD, late-life depression comorbid with amnestic mild cognitive impairment.