Inhibitory control and affective perception in dementia of the Alzheimer type

The current study examined whether emotional dysregulation characteristic of Alzheimer's disease (AD) reflects abnormalities in inhibition. Generalized impairment in selective attention associated with AD and evidence that emotion becomes an increasingly salient motive directing cognition with age, suggest a linkage between deficient inhibition and emotional dysfunction. Neurophysiological evidence indicates the frontal lobes, thought to mediate inhibition, and the amygdala are involved in cerebral networks controlling emotion. Neuroimaging studies reveal damage to these regions early in AD. Given that AD patients exhibit abnormalities in emotional behavior, deficiencies in modulating attention may impair processing emotional stimuli.;Emotional Stroop and traditional Stroop paradigms were administered to mild and moderately impaired individuals with AD and healthy elderly. Analyses examined whether individuals with AD are significantly impaired relative to healthy elderly in the latency to color name positive and negative word stimuli relative to neutral stimuli. Planned comparisons tested whether interference increases in relation to dementia severity. Supplementary analyses addressed the relationship between emotional interference and interference to color-conflict stimuli from the traditional Stroop.;After minimizing the impact of heterogeneous variances and reaction time outliers, results were partially consistent with major predictions. Group differences processing color-conflict stimuli were contingent on the method used to calculate interference. Individuals with moderate AD experienced more interference processing emotional words relative to neutral words than individuals with mild AD and healthy elderly who performed comparably. All participants experienced less interference on the last five blocks of trials relative to the first block. Healthy elderly experienced more difficulty processing color-conflict stimuli than negative emotional word stimuli whereas individuals with moderate AD experienced more difficulty processing positive word stimuli relative to color-conflict stimuli.;Differences across groups in interference are related to literature on inhibitory processing and emotion. Deficient inhibitory mechanisms appear to be an insufficient account of emotional dysregulation observed early in AD. Instead, inhibitory processing may be more sensitive to variations in emotional intensity. Methodological limitations challenging the validity of these findings are discussed as well as directions for future research, which may contribute to more valid comments on the relation between inhibition and emotional regulation in AD.