The study aims to examine whether cognitive deficits are different between patients with early stage Alzheimer's disease (AD) and patients with early stage vascular dementia (VaD) using the Korean version of the CERAD neuropsychological battery (CERAD-K-N).

Patients with early stage dementia, global Clinical Dementia Rating (CDR) 0.5 or 1 were consecutively recruited among first visitors to a dementia clinic, 257 AD patients and 90 VaD patients completed the protocol of the Korean version of the CERAD clinical assessment battery. CERAD-K-N was administered for the comprehensive evaluation of the neuropsychological function.

Of the total 347 participants, 257 (69.1%) were AD group (CDR 0.5=66.9%) and 90 (21.9%) were VaD group (CDR 0.5=40.0%). Patients with very mild AD showed poorer performances in Boston naming test (BNT) (P=0.028), word list memory test (P<0.001), word list recall test (P<0.001) and word list recognition test (WLRcT) (P=0.006) than very mild VaD after adjustment of T score of MMSE-KC. However, the performance of trail making A (TMA) was more impaired in VaD group than in AD group. The performance of WLRcT (P<0.001) was the worst among neuropsychological tests within AD group, whereas TMA was performed worst within VaD group.

Patients with early-stage AD have more cognitive deficits on memory and language while patients with early-stage VaD show worse cognitive function on attention/processing speed. In addition, as the first cognitive deficit, memory dysfunction comes in AD and deficit in attention/processing speed in VaD.