Zubenko, Zubenko, McPherson, Spoor, Marin, Fawlow, Smith, Geda,
Cummings, Petersen, & Sunderland (2003) present data supporting the validity
of a specific syndrome:
Major Depressive Syndrome of Alzheimer's Disease
They feel this is a distinct diagnostic entity and "may
be among the most common mood disorders of late life." (p. 865)