Cognitive Neuroscience And NeuropsychologyPhasic visual alertness in Alzheimer's disease and ageingTales, Andrea1 2 CA; Muir, Janice L.1; Bayer, Antony3; Jones, Roy4; Snowden, Robert J.1 Author Information 1School of Psychology, Cardiff University, Cardiff CF11 3YG 3Department of Geriatric Medicine, Llandough Hospital, Penlan Road, Penarth CF64 2XX 4The Research Institute for the Care of the Elderly, St. Martin's Hospital, Bath, BA2 5RP, UK 2Present Address: The BRACE Centre, Department of Care of the Elderly, Bristol University, Blackberry Hill Hospital, Manor Road, Bristol, UK CACorresponding Author: [email protected] Received 20 June 2002; accepted 19 September 2002 NeuroReport: December 20, 2002 - Volume 13 - Issue 18 - p 2557-2560 Buy Abstract An individual's ability to see and react quickly to a target stimulus is enhanced if they are alerted to the arrival of this target by a stimulus that occurs just prior in time to it. This alerting effect is thought to occur due to a phasic increase in alertness mediated by noradrenergic activity. In Alzheimer's disease (AD) there is a dysfunction in the noradrenergic system resulting in a decrease in central levels of noradrenaline. We therefore predicted that patients with AD would not be able to benefit from the prior stimulus to the same extent as that seen in healthy older adults and thus would have a reduced or abolished alerting-effect. We measured reaction times to respond to a visual target that could be preceded (by 200 ms) by a visual alerting cue, in 17 patients with Alzheimer's disease, 19 age-matched controls and 13 younger controls. We found that the alerting cue significantly decreased the reaction times for both the young and old controls, but that this cue had no effect upon the reaction times for those with AD. This marked inability to increase phasic alertness in AD may contribute to the everyday problems faced by these patients, and may provide a simple tool to aid diagnosis and disease progression. © 2002 Lippincott Williams & Wilkins, Inc.