We studied the effects of an electromagnetic field (EMF) as emitted by a 902 MHz mobile phone on human short term memory. This study was a replication with methodological improvements to our previous study. The improvements included multi-centre testing and a double blind design. A total of 64 subjects (32 men) in two independent laboratories performed a short term memory task (n-back) which poses a varying memory load (0-3 items) on the subjects' memory. They performed the task twice, once each under EMF and sham exposure. Reaction times (RTs) and accuracy of the responses were recorded. The order of exposure and memory load conditions were counterbalanced across subjects and gender. There were no statistically significant differences in performance between the two laboratories. We could not replicate our previous results: the EMF had no effect on RTs or on the accuracy of the subjects' answers. The inability to replicate previous findings could have been caused by lack of actual EMF effects or the magnitude of effects being at the sensitivity threshold of the test used.
Aggregation of the amyloid-beta-42 (Abeta42) peptide in the brain parenchyma is a pathological hallmark of Alzheimer's disease (AD), and the prevention of Abeta aggregation has been proposed as a therapeutic intervention in AD. However, recent reports indicate that Abeta can form several different prefibrillar and fibrillar aggregates and that each aggregate may confer different pathogenic effects, suggesting that manipulation of Abeta42 aggregation may not only quantitatively but also qualitatively modify brain pathology. Here, we compare the pathogenicity of human Abeta42 mutants with differing tendencies to aggregate. We examined the aggregation-prone, EOFAD-related Arctic mutation (Abeta42Arc) and an artificial mutation (Abeta42art) that is known to suppress aggregation and toxicity of Abeta42 in vitro. In the Drosophila brain, Abeta42Arc formed more oligomers and deposits than did wild type Abeta42, while Abeta42art formed fewer oligomers and deposits. The severity of locomotor dysfunction and premature death positively correlated with the aggregation tendencies of Abeta peptides. Surprisingly, however, Abeta42art caused earlier onset of memory defects than Abeta42. More remarkably, each Abeta induced qualitatively different pathologies. Abeta42Arc caused greater neuron loss than did Abeta42, while Abeta42art flies showed the strongest neurite degeneration. This pattern of degeneration coincides with the distribution of Thioflavin S-stained Abeta aggregates: Abeta42Arc formed large deposits in the cell body, Abeta42art accumulated preferentially in the neurites, while Abeta42 accumulated in both locations. Our results demonstrate that manipulation of the aggregation propensity of Abeta42 does not simply change the level of toxicity, but can also result in qualitative shifts in the pathology induced in vivo.
To assess the ability and accuracy of elderly men to recall their weights and determine what characteristics might predict recall ability and accuracy.
Eight hundred sixty-nine elderly men (mean age, 84 years), participants of the Manitoba Follow-up Study (MFUS), responded to a questionnaire asking them to recall their weights at ages 20, 30, 50, and 65 years. Recalled weights were compared with measured weights collected since MFUS began in 1948. Logistic regression was used to predict ability and accuracy of weight recall.
Only 75% of respondents attempted to recall their weights at all 4 ages. Among men recalling 4 weights, fewer than half were accurate within +/- 10%, just 7% were within +/- 5% of their measured weights. Accuracy of recall was significantly and independently associated with body mass index during middle age (5 kg/m(2)) (odds ratio 0.83, 95% confidence interval: 0.76, 0.90) and weight change. Unmarried men were less likely than married men to attempt recalling all 4 weights. Men overweight at middle age were more likely to underestimate their recalled weights.
Studies relating weight in early adulthood or middle age with outcomes in later life should not rely on elderly male participants recalling those weights.
The acceptable noise level (ANL) test is a method for quantifying the amount of background noise that subjects accept when listening to speech. Large variations in ANL have been seen between normal-hearing subjects and between studies of normal-hearing subjects, but few explanatory variables have been identified.
To explore a possible relationship between a Swedish version of the ANL test, working memory capacity (WMC), and auditory evoked potentials (AEPs).
ANL, WMC, and AEP were tested in a counterbalanced order across subjects.
Twenty-one normal-hearing subjects participated in the study (14 females and 7 males; aged 20-39 yr with an average of 25.7 yr).
Reported data consists of age, pure-tone average (PTA), most comfortable level (MCL), background noise level (BNL), ANL (i.e., MCL - BNL), AEP latencies, AEP amplitudes, and WMC. Spearman's rank correlation coefficient was calculated between the collected variables to investigate associations. A principal component analysis (PCA) with Varimax rotation was conducted on the collected variables to explore underlying factors and estimate interactions between the tested variables. Subjects were also pooled into two groups depending on their results on the WMC test, one group with a score lower than the average and one with a score higher than the average. Comparisons between these two groups were made using the Mann-Whitney U-test with Bonferroni correction for multiple comparisons.
A negative association was found between ANL and WMC but not between AEP and ANL or WMC. Furthermore, ANL is derived from MCL and BNL, and a significant positive association was found between BNL and WMC. However, no significant associations were seen between AEP latencies and amplitudes and the demographic variables, MCL, and BNL. The PCA identified two underlying factors: One that contained MCL, BNL, ANL, and WMC and another that contained latency for wave Na and amplitudes for waves V and Na-Pa. Using the variables in the first factor, the findings were further explored by pooling the subjects into two groups according to their WMC (WMClow and WMChigh). It was found that the WMClow had significantly poorer BNL than the WMChigh.
The findings suggest that there is a strong relationship between BNL and WMC, while the association between MCL, ANL, and WMC seems less clear-cut.
Performance on measures of implicit social cognition has been shown to vary as a function of the momentary accessibility of relevant information. The present research investigated the mechanisms underlying accessibility effects of self-generated information on implicit measures. Results from 3 experiments demonstrate that measures based on response compatibility processes (e.g., Implicit Association Test, affective priming with an evaluative decision task) are influenced by subjective feelings pertaining to the ease of retrieving relevant information from memory, whereas measures based on stimulus compatibility processes (e.g., semantic priming with a lexical-decision task) are influenced by direct knowledge activation in associative memory. These results indicate that the mediating mechanisms underlying context effects on implicit measures can differ as a function of the task even when these tasks show similar effects on a superficial level. Implications for research on implicit social cognition and the ease-of-retrieval effect are discussed.
We present a Finland-Swedish adaptation of the Sweden-Swedish group screening test for dyslexia for adults and young adults DUVAN (Lundberg & Wolff, 2003) together with normative data from 143 Finland-Swedish university students. The test is based on the widely held phonological deficit hypothesis of dyslexia and consists of a self-report and five subtests tapping phonological working memory, phonological representation, phonological awareness, and orthographic skill. We describe the test adaptation procedure and show that the internal reliability of the new test version is comparable to the original one. Our results indicate that the language background (Swedish, Finnish, early simultaneous Swedish-Finnish bilingualism) should be taken into account when interpreting the results on the Finland-Swedish DUVAN test. We show that the FS-DUVAN differentiates a group of students with dyslexia diagnosis from normals, and that a low performance on the FS-DUVAN correlates with a positive self-report on familial dyslexia and with a history of special education in school. Finally, we analyze the sensitivity and specificity of the FS-DUVAN for dyslexia among university students.