Evidence of Impaired Glucose Tolerance and Insulin Resistance in Patients With Alzheimer’s Disease

Alzheimer’s disease (AD) and diabetes rarely occur together, a finding that provides a possible clue as to the development of AD. Abnormal glucose metabolism is not limited to diabetes, but also can include impaired glucose tolerance, insulin resistance, and hyperinsulinemia. AD patients have significantly varying insulin levels after drinking sugared sodas and thus may be classified as insulin resistant. After reviewing the literature on impaired glucose tolerance and insulin production in AD, we present several hypotheses as possible explanations for the relationship between insulin resistance and AD. Finally, we suggest future studies, including studies on use of thiazolidinediones (currently used in the treatment of diabetes) in AD.     

Eyeblink classical conditioning differentiates normal aging from Alzheimer’s disease

Eyeblink classical conditioning is a useful paradigm for the study of the neurobiology of learning, memory, and aging, which also has application in the differential diagnosis of neurodegenerative diseases expressed in advancing age. Converging evidence from studies of eyeblink conditioning in neurological patients and brain imaging in normal adults document parallels in the neural substrates of this form of associative learning in humans and non-human mammals. Age differences in the short-delay procedure (400 ms CS-US interval) appear in middle age in humans and may be caused at least in part by cerebellar cortical changes such as loss of Purkinje cells. Whereas the hippocampus is not essential for conditioning in the delay procedure, disruption of hippocampal cholinergic neurotransmission impairs acquisition and slows the rate of learning. Alzheimer’s disease (AD) profoundly disrupts the hippocampal cholinergic system, and patients with AD consistently perform poorly in eyeblink conditioning. We hypothesize that disruption of hippocampal cholinergic pathways in AD in addition to age-associated Purkinje cell loss results in severely impaired eyeblink conditioning. The earliest pathology in AD occurs in entorhinal cortical input to hippocampus, and eyeblink conditioning may detect this early disruption before declarative learning and memory circuits become impaired. A case study is presented in which eyeblink conditioning detected impending dementia six years before changes on other screening tests indicated impairment. Because eyeblink conditioning is simple, non-threatening, and non-invasive, it may become a useful addition to test batteries designed to differentiate normal aging from mild cognitive impairment that progresses to AD and AD from other types of dementia.     

User-controlled photographic animations, photograph-based questions, and questionnaires: Three Internet-based instruments for measuring drivers’ risk-taking behavior

The Internet has been exploited successfully in the past as a medium for behavioral research. This paper presents a series of studies designed to assess Internet-based measures of drivers’ risk-taking behavior. First, we compared responses from an Internet sample with a traditional pencil-and-paper sample using established questionnaire measures of risk taking. No significant differences were found. Second, we assessed the validity of new Internet-based instruments, involving photographs and photographic animations, that measured speed, gap acceptance, and passing. Responses were found to reflect known demographic patterns of actual behavior to some degree. Also, a roadside survey of speeds was carried out at the locations depicted in the photographic measure of speeding and, with certain exceptions, differences between the two appeared to be constant. Third, a between-subject experimental manipulation involving the photographic animation measure of gap acceptance was used to demonstrate one application of these techniques.     

Retrieval conditions and false recognition: testing the distinctiveness heuristic

High levels of false recognition are observed after people study lists of semantic associates that all converge on a nonpresented lure word. In previous experiments, we have found that orienting participants to encode distinctive information about study list items by presenting them as pictures as opposed to words produces marked reductions in false recognition. We have suggested that these reductions reflect the operation of a distinctiveness heuristic: Participants demand access to detailed pictorial information in order to support a positive recognition decision. The present experiments provide additional evidence on this point and allow us to distinguish between the distinctiveness heuristic account and an alternative account based on the impoverished encoding of relational information that occurs when one is studying pictures. In Experiment 1, even when only half of the items in a study list were presented as pictures, a general suppression of false recognition was observed that could be attributable to impoverished encoding of relational information. Experiment 2 provided a critical test of the distinctiveness heuristic account: We manipulated test instructions and found that differences in false recognition rates between picture and word encoding were attenuated in a retrieval condition that did not encourage reliance on a distinctiveness heuristic.     

Fin-de-siècle ranking of important psychologists by a sample of undergraduate students enrolled in history of psychology

134 undergraduate students of the history of psychology from 1998 through 2000 were requested to name three psychologists in order of importance, eminence, or influence within as well as outside the discipline of psychology. Salient was confirmation of Sigmund Freud as outranking other psychologists by a wide margin.     

Two- and three-factor solutions of the WAIS-III

The third edition of the Wechsler Adult Intelligence Scale manual reports four-factor solutions for the WAIS-III, and subsequent research has validated four-factor solutions for a variety of samples. These four factors consistently correspond to the four Factor Indexes that are yielded by the WAIS-III. However, the WAIS-III still provides Verbal and Performance IQs, in addition to the Indexes, making it desirable to examine two-factor solutions as well. In addition, because the Wechsler literature includes much interpretation of three-factor solutions, these solutions were likewise examined. Principal factor analysis followed by Varimax and Oblimin rotations of two and three factors were performed on data for the total WAIS-III sample ages 16 to 89 years (N=2,450). The two-factor solutions were viewed as a construct validation of Wechsler's two separate IQs, although the Working Memory subtests tended to load higher on the Performance scale than on their intended scale (Verbal); three-factor solutions were interpreted within the context of Horn's expanded fluid-crystallized theory and research on working memory. Both the two- and three-factor Varimax-rotated solutions were related to similar factor analyses conducted previously for the Wechsler Adult Intelligence Scale-Revised and the Wechsler Intelligence Scale for Children-III. Coefficients of congruence between like-named factors consistently exceeded .90, and usually .98, across different Wechsler batteries.     

Improving Decision Making by Means of Dissent1

Antidotes to problems associated with uniformity of viewpoints have generally involved dissent in one form or another (Katzenstein, 1996), one being “devil's advocate.” Research on authentic dissent has documented additional advantages in that it stimulates divergent and original thought (Nemeth, 1995). In this study, authentic disscnt was compared with devil's advocate and with no dissent. Findings indicate that authentic dissent was superior in (a) stimulating a greater proportion of original thoughts, (b) considering the opposite position, and (c) direct attitude change. Devil's advocate was found to stimulate cognitive boistcring of the initial position, thus raising concerns about the unintended consequences of techniques such as devil's advocate and the subtle task facing attempts to foster original thought and yet maintain cohesion.     

Hindsight bias and causal reasoning: a minimalist approach

What factors contribute to hindsight bias, the phenomenon whereby the known outcome of an event appears obvious only after the fact? The Causal Model Theory (CMT) of hindsight bias (Nestler et al. in Soc Psychol 39:182–188, 2008a; in J Expl Psychol: Learn Mem Cog 34:1043–1054, 2008b; Pezzo in Mem 11:421–441, 2003; Wasserman et al. in Pers Soc Psychol Bull 17:30–35, 1991) posits that hindsight bias can occur when people have the opportunity to identify potential causal antecedents and evaluate whether they could have led to the outcome. Two experiments incorporating highly controlled minimalist scenarios supported the CMT. As predicted by the CMT, hindsight bias occurred when the causal factor explained the actual outcome better than the alternative outcome, and reverse hindsight bias occurred when the causal factor explained the alternative outcome better than the actual outcome. Moreover, we found new evidence that outcome knowledge alone was insufficient to elicit hindsight bias in the absence of a potential causal antecedent. Implications for future directions in hindsight bias research are discussed.