Although depression is a common psychiatric symptom in Alzheimer's disease (AD), there has not been a lot of research on neuropsychological characteristics of this symptom. To determine the characteristic neuropsychological deficit in patients with depression compared to patients without depression, this study compared each neuropsychological test between AD patients with depression and without depression.

Psychotropic-naïve (drug-naïve) early stage [Clinical Dementia Rating Scale (CDR)=0.5 or CDR=1] probable AD patients with depression ( n =77) and without depression ( n =179) were assessed with the Seoul Neuropsychological Screening Battery, which includes measures of memory, intelligence, and executive functioning.

AD patients with depression had lower scores on the digit forward, digit backward, calculation, and Color Word Stroop Test tests compared to AD patients without depression.

Our study showed that AD patients with depression have disproportionate cognitive deficit, suggesting frontal (especially in the left dorsolateral), left hemisphere and left parietal dysfunction. Considering the neuropsychological differences between AD patients with depression and without depression, depression may have specific anatomic substrates.