Association of prion protein with cognitive functioning in humans

Objectives

Recent animal studies have suggested a key role for cellular prion protein (PrPc) in the pathological consequences of amyloid plaque formation, the hallmark of Alzheimer's disease. This epidemiological study investigated whether serum concentrations of PrPc are associated with cognitive functioning in humans.

Design, Setting, Participants

Cross-sectional study of 1,322 participants from the elderly general population in Germany, aged 65 + years at baseline (2000–2002).

Measurements

Cognitive functioning was assessed by the COGTEL phone interview 5 years after baseline. Serum PrPc was determined by a commercial immunoassay.

Results

In multiple linear regression adjusted for important confounders, subjects in higher PrPc quintiles appeared to have lower cognitive functioning scores than those in the lowest PrPc quintile. Spline regression suggested pronounced non-linearity with an inverse association between PrPc and cognitive functioning levelling off beyond median PrPc. Cognitive subdomain-specific models produced somewhat heterogeneous results.

Conclusion

The findings are suggestive of an independent association of PrPc with cognitive functioning in humans. Confirmatory and longitudinal studies are needed to elucidate the potential of PrPc for applications in early risk stratification for cognitive impairment.     

Cognitive status and development in the oldest old: a longitudinal analysis from the Heidelberg Centenarian Study

In the present study, we investigated cognitive status, cognitive development and the effect of mortality on cognitive changes in very old age. Analyzing data from the population-based Heidelberg Centenarian Study, results revealed that centenarians differed quite strongly in their cognitive capacities. While about half of the population showed moderate to severe cognitive impairment, one quarter was found to be cognitively intact. Moreover, analyzing cognitive change over a period of 1.5 years, centenarians' cognitive performance was revealed to be rather stable. Finally, only a small effect of mortality on cognitive status and changes was detected, supporting a recent hypothesis that the terminal decline or drop in cognitive functioning decreases in very old age.     

CPR courses and semi-automatic defibrillators--life saving in cardiac arrest?

OBJECTIVES: The aim was to assess the knowledge of life-supporting first-aid in both cardiac arrest survivors and relatives, and their willingness to have a semi-automatic external defibrillator in their homes and use it in an emergency. MATERIAL AND METHODS: Cardiac arrest survivors, their families, friends, neighbours and co-workers were interviewed by medical students using prepared questionnaires. Their knowledge and self-assessment of life-supporting first-aid, their willingness to have a semi-automatic defibrillator in their homes and their willingness to use it in an emergency before and after a course in cardiopulmonary resuscitation (CPR) with a semi-automatic external defibrillator was evaluated. Courses were taught by medical students who had received special training in basic and advanced life support. RESULTS: Both patients and relatives, after a course of 2-3 h, were no longer afraid of making mistakes by providing life-supporting first-aid. The automated external defibrillator (AED) was generally accepted and considered easy to handle. CONCLUSION: We consider equipping high-risk patients and their families with AEDs as a viable method of increasing their survival in case of a recurring cardiac arrest. This, of course, should be corroborated by further studies.     

Life-long intellectual activities mediate the predictive effect of early education on cognitive impairment in centenarians: a retrospective study

The purpose of this study was to examine the hypothesis of whether early education and/or maintaining intellectual activities over the life-course have the power to protect against cognitive impairment even in extremely old adults. Ninety centenarians from the population-based Heidelberg Centenarian Study were assessed with a modified version of the Mini Mental State Exam (MMSE). Data about education, occupational status, and life-long intellectual activities in four selected domains were obtained. Results demonstrated that 52% of the sample showed mild-to-severe cognitive impairment. Analyzing the influence of early education, occupational status, and intellectual activities on cognitive status we applied several (logistic) regression analyses. Results revealed independent, significant and strong influence of both formal school education and intellectual activities on the cognitive status in very late life, even after controlling for occupational status. However, about one fourth of the effect of early education on cognitive status was exerted indirectly via the assessed intellectual activities. In summary, the present study provides first evidence for the conclusion that even with regard to cognitive performance in very old age, both early education and life-long intellectual activities seem to be of importance.     

Funktionale Kompetenz und Pflegebedürftigkeit nach SGB XI bei Hundertjährigen

The maintenance of autonomy and independence in the oldest old population is at high risk due to the inevitable aging process, which primarily affects functional and cognitive capacities. In this study, we investigate centenarians to assess the extent in which they have lost their ability to live independently. This is done with a classification system for dependency that considers both functional and cognitive limitations and determines the level of functional competence in this population. Based on this system, we evaluate the necessity for nursing care and investigate to which extent their actual needs are covered by the German Long-term Care Insurance. An important and relevant question is whether this system even addresses the evaluation of cognitive impairment. For this reason, 85 centenarians and their proxies were assessed with standardized instruments and the results show a severe loss of independence. The necessity for at least daily contact with nursing care was identified in 91 percent of the centenarians due to their dramatically limited capacities. Forty-four percent of the centenarians need more support than they actually receive from the German Long-term Care Insurance. Therefore, considering cognitive impairment is a crucial component in the evaluation, which would lead to more support by the official system in 20 percent of the centenarians. The considerable differences between the granted and the necessary nursing care demonstrate that co-operation from family members must be heavily relied upon.     

The role of dual-task and task-switch in prospective memory: Behavioural data and neural correlates

Event-based prospective memory (PM) requires remembering the delayed execution of an intended action in response to a pre-specified PM cue while being actively engaged in an ongoing task in which the cue is embedded. To date, experimental paradigms vary as to whether or not they require participants immediately to stop working on the ongoing task whenever they encounter a PM event (cue) and directly switch to the prospective action (task-switch approach). Alternatively, several other paradigms used in the literature encourage participants to continue working on the ongoing task item after the cue, and only then, perform the prospective action (dual-task approach). The present study explores the possible behavioural and electrophysiological effects that both approaches may have on PM performance. Seventeen young adults performed both versions of a standard PM task in a counterbalanced order during which behavioural data and electroencephalogram (EEG) were recorded. Behavioural data showed a decrement in PM performance in the task-switch compared to the dual-task condition. In addition, EEG data revealed differences between the dual-task and task-switch approach in event-related potential (ERP) components associated with response inhibition and with post-retrieval monitoring (i.e. late positive complex). No differences between the two tasks were found with regard to the PM event detection processes (i.e. N300) and the retrieval of the intended action from long-term memory. In sum, findings demonstrate that it does make a difference which task approach is applied and suggest that dual-task and task-switch paradigms may result in different processing and neurophysiological dynamics particularly concerning attentional resources and cognitive control.     

Traumatic brain injury and prospective memory: influence of task complexity

A quantitative review indicated that prospective memory impairment is a consistent feature of traumatic brain injury (TBI). However, evidence also suggests that manipulations that increase demands on controlled attentional processes moderate the magnitude of observed deficits. A total of 16 TBI participants were compared with 15 matched controls on a task in which the number of prospective target events was manipulated. This manipulation was of interest because two competing models make different predictions as to its effect on controlled attentional processes. In the context of Smith and Bayen's (2004) preparatory attentional processes and memory processes (PAM) model increasing the number of target events should increase requirements for controlled attentional processing. In contrast, McDaniel and Einstein's (2000) multiprocess framework assumes that distinct target events presented in focal awareness of the processing activities required for the ongoing task are likely to depend on automatic processes. This latter model therefore leads to the prediction that increasing the number of target events should not increase demands upon controlled attentional processes. Consistent with McDaniel and Einstein's (2000) multiprocess framework, TBI patients were significantly and comparably impaired on the one- and the four-target-event conditions relative to controls. Further, TBI deficits could not be attributed to increased difficulty with the retrospective component of the prospective memory task. The practical and theoretical implications of these results are discussed.