Screening tests that briefly measure early signs of cognitive dysfunction in Alzheimer's disease (AD) are lacking. We devised a new scale focused on early detecting cognitive dysfunction: the Attention Questionnaire Scale (AQS). We prospectively studied the AQS in 268 subjects with varying degrees of cognitive dysfunction and compared it with the Mini-Mental Status Examination (MMSE), digit span test, trail making test part B, letter cancellation test, Instrumental ADL, Geriatric Depression Scale, and Clinical Dementia Rating Scale. The internal consistency was excellent with the AQS (Cronbach's α = 0.945). There were significant differences in the overall AQS scores across varying degree of cognitive dysfunction (26.80 ± 3.43 in normal elderly, 20.78 ± 4.83 in patients with mild cognitive impairment (MCI), 19.01 ± 4.49 in early AD, 16.00 ± 5.03 in mild AD, and 12.02 ± 6.28 in moderate AD), and subjects with the early stage of cognitive dysfunction could be further distinguished using the AQS than MMSE. The area under the receiver operating characteristic curve was estimated to be 0.93 (95% confidence interval 0.89-0.97) in screening for normal elderly versus patients with MCI or various stages of AD. The AQS provides greater screening ability for early stage cognitive dysfunction, used not only as a screening tool but also an appropriate simple questionnaire.