Deficient Symbol Processing in Alzheimer Disease

Abstract

Symbols and signs have been suggested to improve the orientation of patients suffering from Alzheimer disease (AD). However, there are hardly any studies that confirm whether AD patients benefit from signs or symbols and which symbol characteristics might improve or impede their symbol comprehension. To address these issues, 30 AD patients and 30 matched healthy controls performed a symbol processing task (SPT) with 4 different item categories. A repeated-measures analysis of variance was run to identify impact of different item categories on performance accuracy in both the experimental groups. Moreover, SPT scores were correlated with neuropsychological test scores in a broad range of other cognitive domains. Finally, diagnostic accuracy of the SPT was calculated by a receiver-operating characteristic curve analysis. Results revealed a global symbol processing dysfunction in AD that was associated with semantic memory and executive deficits. Moreover, AD patients showed a disproportional performance decline at SPT items with visual distraction. Finally, the SPT total score showed high sensitivity and specificity in differentiating between AD patients and healthy controls. The present findings suggest that specific symbol features impede symbol processing in AD and argue for a diagnostic benefit of the SPT in neuropsychological assessment.

Spatial Mental Transformation Skills Discriminate Fitness to Drive in Young and Old Adults

“…In other studies, older drivers showed impairments in both accuracy and speed of understanding traffic signs (Stutts et al, 1998;Ben-Bassat and Shinar, 2015;Schulz et al, 2019). The reduced comprehension of traffic signs was found to be mainly associated with age-related changes in selective attention, speed perception, and semantic memory (Lesch et al, 2013;Boot et al, 2014;Toepper et al, 2014).…”

Dissociating Normal Aging from Alzheimer’s Disease: A View from Cognitive Neuroscience

“…Common examples are symbol comprehension [167] or driving skills [168], both of which contribute to autonomy in everyday life.…”

Preliminary Validation of a Questionnaire Covering Risk Factors for Impaired Driving Skills in Elderly Patients

“…A correct interpretation of these signs by semantic-associative processes is often not possible either, because many of these signs are too abstract to be understood without mnemonic information. Moreover, symbol comprehension was found to be impaired in AD [12] which also applies to traffic symbols [13]. Together, these findings suggest that future approaches differentiating between fit and unfit drivers should not exclusively focus on impaired attentional processes but also include executive and memory tasks.…”

“…Besides memory deficits, impaired executive processes are reported [6,7,8], e.g., inhibitory dysfunctions [9]. Moreover, AD is often characterized by disorientation [10,11] and impaired symbol comprehension [12], the latter of which also affects the correct interpretation of traffic signs [13].…”