Time estimation in mild Alzheimer's disease patients

Abstract

Background: Time information processing relies on memory, which greatly supports the operations of hypothetical internal timekeepers. Scalar Expectancy Theory (SET) postulates the existence of a memory component that is functionally separated from an internal clock and other processing stages. SET has devised several experimental procedures to map these cognitive stages onto cerebral regions and neurotransmitter systems. One of these, the time bisection procedure, has provided support for a dissociation between the clock stage, controlled by dopaminergic systems, and the memory stage, mainly supported by cholinergic neuronal networks. This study aimed at linking the specific memory processes predicted by SET to brain mechanisms, by submitting time bisection tasks to patients with probable Alzheimer's disease (AD), that are known to present substantial degeneration of the fronto-temporal regions underpinning memory.

Intra-Individual Reaction Time Variability in Mild Cognitive Impairment and Alzheimer’s Disease: Gender, Processing Load and Speed Factors

“…In the study of RT SPEED and IIV RT there are many factors in addition to the ones investigated here, potentially capable of influencing both the speed and variability of processing in ageing, aMCI + and AD and thus warrant further investigation. Such factors include fatigue and practice effects, stimulus characteristics, sensory-motor integration, decision and response and temporal factors, e.g., [94]. Finally, a larger sample size would more confidently confirm differences and would have permitted also the potentially more clinically appropriate comparison of female patients with female controls and male patients with male controls.…”

Maladie d’Alzheimer et appropriation de la durée d’action

“…La participation des processus attentionnels est dé montré e [7,26], ce qui té moigne des difficulté s que rencontrent les patients atteints de MA pour allouer des ressources à deux tâches simultané ment. En tâche de bissection temporelle-discrimination de duré es diffé rentes, les ré ponses des patients MA sont plus variables et moins pré cises que celles des sujets contrôles [8] et ce, plus particuliè rement aux alentours de la seconde. Les estimations de duré e supé rieures à la seconde semblent requé rir des capacité s cognitives plus importantes au niveau mné sique et attentionnel que celles des duré es courtes [25].…”

Time Estimation and Production in HIV-Associated Neurocognitive Disorders (HAND)

“…The methods most commonly used are tests of time estimation (i.e., the examinee must report how long a time interval lasted), production (i.e., the examinee is told the interval length and must produce the duration in some way), and reproduction tasks (i.e., the examinee is shown a time duration and must reproduce that duration in some way), with the latter two thought to be most taxing on executive functioning resources (e.g., Barkley, Murphy, & Bush, 2001). Time misperception is evident in several clinical populations, including Parkinson’s (Pastor, Artieda, Jahanshahi, & Obeso, 1992), Huntington’s (Beste et al, 2007), and Alzheimer’s (Caselli, Iaboli, & Nichelli, 2009) diseases, but there are no well-established population differences with respect to the pattern of effects across the three types of time perception measurements.…”