Phasic visual alertness in Alzheimerʼs disease and ageing

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.

The effect of multisensory cues on attention in aging

“…Overall, when presented with more than one pair of bilateral sensory inputs (e.g., somatosensory pulses with concurrent visual asterisks), both age groups demonstrated multisensory alerting effects that were not facilitative and not comparable to those previously described using unisensory visual alerting cues (Fernandez-Duque and Black, 2006; Mahoney et al, 2010; Tales et al, 2002). Interestingly, this phenomenon occurred regardless of chronological age, implying that the effect cannot solely be explained by healthy aging.…”

“…Tales et al (2002) used a reaction time task with visual alerting cues and reported comparable benefits of alerting in both young and old groups. Similarly, intact phasic alerting in healthy aging and in Alzheimer’s disease (AD) patients was found using a choice RT task with alerting cues (Nebes and Brady, 1993).…”

vMMN for schematic faces: automatic detection of change in emotional expression

“…We consider the future development of the visual optimal paradigm for the vMMN measurement truly promising as this would considerably facilitate its clinical implementation. Clinically applicable and standardized multi-feature vMMN experiments would be very welcome for diagnostic and treatment-monitoring purposes, for example in the case of Alzheimer’s disease and mild cognitive impairment (e.g., Tanaka et al, 2001; Tales et al, 2002,2008; Tales and Butler, 2006), schizophrenia (Urban et al, 2008) and alcohol intoxication (Kenemans et al, 2010). …”

“…Due to the fact that the (v)MMN has clinical value (e.g., Tanaka et al, 2001; Horimoto et al, 2002; Tales et al, 2002,2008; Lorenzo-López et al, 2004; Tales and Butler, 2006; Hosák et al, 2008; Urban et al, 2008; Kenemans et al, 2010; all recently reviewed together with MMN studies by Näätänen et al, 2011,2012), it certainly calls for rigorous and standardized measurement procedures. Furthermore, a systematic look at this clinical work also reveals the same important discrepancy (i.e., difficulties in controlling one’s attention) between auditory and visual MMNs.…”

Repeated Measurement of the Components of Attention of Older Adults using the Two Versions of the Attention Network Test: Stability, Isolability, Robustness, and Reliability

“…Phasic alertness is typically examined by comparing performance with warning signals and without warning signals. Previous studies show that aging has relatively little effect on phasic alertness (e.g., Rabbitt, 1984; Nebes and Brady, 1993; Tales et al, 2002a) when the stimulus onset asynchrony (SOA) between the warning signal and the target was fixed. However, when SOA was varied within a block, Festa-Martino et al (2004) reported that older adults showed smaller alerting effects than younger adults.…”