Additional univariate two-way analyses of covariance (ANCOVAs) were conducted for the four AMDP subscales (affective flattening/social withdrawal, alogia/mutism, inappropriate affect/incoherence, and reduced interest/restricted thinking), derived from the AMDP-negative and apathy syndromes, to determine whether differences in the subscales between early and late-onset patients are relatively independent of secondary sources of negative symptoms.