Give Me a Sign: Concrete Symbols Facilitate Orientation in Alzheimer's Disease Dementia.

OBJECTIVES: Persons with Alzheimer's disease dementia (ADD) often show impaired orientation, particularly in unknown environments. Signs may offer an opportunity to compensate for these deficits and thus improve participation. METHODS: We assessed 30 persons with ADD and 36 healthy controls by using a sign comprehension paradigm (SCP) in a real-life environment. Nonparametric mixed model analyses of variance were used to analyze the effect of different symbols and additional scripture (coding condition) on SCP performance speed and accuracy. RESULTS: Analyses revealed a significant main effect of symbol design on SCP speed as well as an interaction effect of group × symbol, indicating a benefit of concrete, optimized signs for persons with ADD. Furthermore, analyses of SCP error rates revealed the main effects of group and coding condition as well as an interaction effect of group × coding. Persons with ADD made more errors than healthy controls, but SCP error rates decreased significantly in ADD in the double-coding condition. DISCUSSION: Our findings revealed an advantage of concrete double-coded symbols over conventional symbols and therefore strongly suggest the implementation of concrete double-coded signs to support older people living with ADD.

Impaired Color Discrimination in Alzheimer Disease Dementia.

OBJECTIVE: Patients with Alzheimer disease dementia (ADD) often show impaired orientation and navigation. Signage offers an opportunity to compensate for these deficits, communicate information efficiently and facilitate wayfinding. Certain properties of signs such as colors and contrasts may beneficially affect the uptake and processing of information particularly in ADD patients. METHODS: Thirty-six healthy older adults and 30 ADD patients performed a computerized color perception task that required discriminating different color combinations. The effects of different contrast features on performance accuracy and speed in the 2 experimental groups were examined by nonparametric mixed analysis of variances. RESULTS: Analyses revealed a significant effect of contrast polarity on reaction times, significant effects of group on reaction times and errors as well as a marginally significant interaction of group×color on errors. All participants benefitted from positive contrast polarity (ie, dark target on lighter background) as indicated by increased performance speed. Furthermore, ADD patients reacted slower and less accurate than healthy controls, but showed higher accuracy at black-white and red-yellow than at blue-green color combinations. CONCLUSIONS: Our findings suggest the implementation of signs with positive contrast polarity to ensure faster reactions. In addition, certain color combinations may enhance accuracy, particularly in patients with ADD.

Assessing fitness to drive in older adults: Validation and extension of an economical screening tool.

OBJECTIVES: Due to demographic change, the number of older drivers with impaired driving skills will increase in the next decades. The current study aimed at the validation and extension of the screening tool Safety Advice For Elderly drivers (SAFE) that allows a cost-efficient assessment of driving-related risk factors in older drivers. METHOD: Seventy-four older drivers aged ≥65 years (M = 77 years) recruited from the general population were included in this prospective observational study. Receiver operating characteristic curve (ROC) and hierarchical logistic regression analyses were utilized to examine whether the SAFE and further evidence-based driving-related factors may allow the differentiation between fit and unfit older drivers assessed in standardized on-road driving assessments. RESULTS: ROC analyses revealed significant diagnostic accuracy of the number of SAFE risk factors in differentiating between fit and unfit older drivers (AUC = 0.71). A stepwise logistic regression model revealed that adding further evidence-based risk factors into the SAFE clearly improved diagnostic accuracy (AUC = 0.85). DISCUSSION: The current study shows that the risk assessed by the SAFE predicts on-road driving fitness in older adults. However, the results also suggest a need for a modification of the SAFE by the inclusion of additional evidence-based risk factors. With sensitivity and specificity scores of about 90 % and 75 %, this modified version may be more suitable for clinical use.

Avoidance Behavior Is an Independent Indicator of Poorer On-road Driving Skills in Older Adults.

OBJECTIVES: The aim of the current work was to investigate the relationship between avoidance of specific driving situations and on-road driving skills in older drivers considering factors found to be related to both avoidance behavior and driving skills. METHOD: Seventy-two older drivers (M = 76 years) from the general population were included in this study. Self-reported avoidance behavior, driving practice, perceived driving difficulties, driving-related cognitive functions, as well as medical conditions were assessed within two sessions. Standardized on-road assessments served for assessing on-road driving skills in a third session. RESULTS: Self-reported avoidance behavior was associated with reduced driving skills (r = -.41), and this relationship remained significant beyond the influence of cognitive skills, self-reported health, driving practice, and perceived driving difficulties. Specifically, avoidance of driving in bad weather, poor visibility and complicated parking was found to be associated with reduced driving skills. DISCUSSION: This study suggest that avoidance behavior is an independent indicator of impaired driving skills in older drivers. Our results argue against the assumption that avoidance behavior may be a reasonable strategy for safe traffic participation. Longitudinal studies are urgently needed to get more evidence on safety aspects of avoidance behavior.

Symbol Comprehension in Patients With Alzheimer Disease Dementia, Mild Cognitive Impairment, and Major Depressive Disorder.

INTRODUCTION: Previous research suggests that specific symbol features attenuate symbol comprehension deficits in seniors suffering from Alzheimer disease dementia (ADD). However, it remains unclear whether these findings also apply to other disorders associated with cognitive dysfunctions. METHODS: Ninety healthy controls, 30 patients with major depressive disorder (MDD), 35 patients with mild cognitive impairment (MCI), and 55 patients with ADD performed a Symbol Processing Task with 4 different symbol categories. Nonparametric between×within subjects analyses were conducted to examine the impact of different symbol categories on performance accuracy in all experimental groups. RESULTS: Analyses revealed a higher symbol comprehension accuracy in healthy seniors than in MDD, MCI, and ADD patients, with the lowest accuracy rates shown by ADD patients. Although the type of symbol hardly affected performance accuracy in healthy seniors and MDD patients, different symbol categories influenced the performance of MCI and ADD patients significantly. CONCLUSIONS: Our findings indicate that symbols with distracting features impede symbol comprehension in ADD and MCI. Symbols with visual cues, by contrast, facilitate symbol comprehension in ADD and may even be advantageous over standardized symbols used in public life.

Linking CSF and cognition in Alzheimer's disease: Reanalysis of clinical data.

OBJECTIVES: Memory and executive deficits are important cognitive markers of Alzheimer's disease (AD). Moreover, in the past decade, cerebrospinal fluid (CSF) biomarkers have been increasingly utilized in clinical practice. Both cognitive and CSF markers can be used to differentiate between AD patients and healthy seniors with high diagnostic accuracy. However, the extent to which performance on specific mnemonic or executive tasks enables reliable estimations of the concentrations of different CSF markers and their ratios remains unclear. METHODS: To address the above issues, we examined the association between neuropsychological data and CSF biomarkers in 51 AD patients using hierarchical multiple regression analyses. In the first step of these analyses, age, education and sex were entered as predictors to control for possible confounding effects. In the second step, data from a neuropsychological test battery assessing episodic memory, semantic memory and executive functioning were included to determine whether these variables significantly increased (compared to step 1) the explained variance in Aß42 concentration, p-tau concentration, t-tau concentration, Aß42/t-tau ratio, and Aß42/Aß40 ratio. RESULTS: The different models explained 52% of the variance in Aß42/t-tau ratio, 27% of the variance in Aß42 concentration, and 28% of the variance in t-tau concentration. In particular, Aß42/t-tau ratio was associated with verbal recognition and code shifting, with Aß42 being related to verbal recognition and t-tau being related to code shifting. By contrast, the inclusion of neuropsychological data did not allow reliable estimations of Aß42/Aß40 ratio or p-tau concentration. CONCLUSION: Our results showed that strong associations exist between the cognitive key symptoms of AD and the concentrations and ratios of specific CSF markers. In addition, we revealed a specific combination of neuropsychological tests that may facilitate reliable estimations of CSF concentrations, thereby providing important diagnostic information for non-invasive early AD detection.

Deficient symbol processing in Alzheimer disease.

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.