Food intake rates of inactive fish are positively linked to boldness in three-spined sticklebacks Gasterosteus aculeatus.

To investigate the link between personality and maximum food intake of inactive individuals, food-deprived three-spined sticklebacks Gasterosteus aculeatus at rest in their home compartments were provided with ad libitum prey items. Bolder individuals ate considerably more than shyer individuals, even after accounting for body size, while sociability did not have an effect. These findings support pace-of-life theory predicting that life-history strategies are linked to boldness.

Age differences in speed of processing are partially mediated by differences in axonal integrity.

Advanced age is associated with declines in brain structure and in cognitive performance, but it is unclear which aspects of brain aging mediate cognitive declines. We inquired if individual differences in white matter integrity contribute to age differences in two cognitive domains with established vulnerability to aging: executive functioning and speed of processing. The participants were healthy volunteers aged 50-81, some of whom had elevated blood pressure, a known vascular risk factor. Using latent variable analyses, we examined whether age differences in regional white matter integrity mediated age-related differences in executive functions and speed of processing. Although diffusion-related latent variables showed stronger age differences than white matter volumes and white matter hyperintensity volumes, only one of them was significantly associated with cognitive performance. Smaller linear anisotropy partially mediated age-related reduction in speed of processing. The effect was significant in posterior (temporal-parietal-occipital) but not anterior (frontal) region, and appeared stronger for cognitive rather than reaction time measures of processing speed. The presence of hypertensive participants did not affect the results. We conclude that in healthy adults, deterioration of axonal integrity and ensuing breech of connectivity may underpin age-related slowing of information processing.

School Achievement in Early Adolescence Is Associated With Students' Self-Perceived Executive Functions.

The primary aim of this study was to investigate the relation between self-perceived executive functions (EFs) and the school achievement of young adolescents (aged 10-12 years), while controlling for parental education and sex. We specifically focused on executive aspects of daily life behavior and the higher-order EFs, as measured with self-report, rather than on the more basic EFs which have been the primary focus of prior investigations. In two independent samples of sixth graders (N > 200 each), students evaluated their EFs on a self-report questionnaire, the Amsterdam Executive Functioning Inventory. School achievement in the domains of mathematics and reading comprehension were evaluated with nationally used, norm-based achievement tests. Results revealed that the self-perceived EFs of young adolescents were significantly correlated with their school achievement in both study samples. School achievement was also correlated with the level of parental education, but the factor sex did not have such influence. In study 1, self-perceived EFs explained additional variance in school achievement, while controlling for parental education and sex. In study 2, this was only the case for the most robust measure of school achievement, i.e., the end-of-primary-school final achievement test. Furthermore, besides the relation with achievement tests, we also found a relation between self-perceived EFs and teacher ratings behavioral problems in the classroom. Together, our findings imply that young students can properly reflect on the effectiveness and appropriateness of their EFs in a way that is relevant to their academic achievement and classroom behavior. The findings underscore the importance of considering the development of EFs and parental education in the evaluation of academic achievements in early adolescence.

Multiple indicators of age-related differences in cerebral white matter and the modifying effects of hypertension.

We investigated differences associated with age and hypertension, a common risk factor for vascular disease, in three aspects of white matter integrity--gross regional volumes of the white matter, volume of the white matter hyperintensities (WMH) and diffusion properties. We acquired MRI scans on 93 adult volunteers (age 50-77 years; 36 with diagnosis of hypertension or elevated blood pressure), and obtained all measures in seven brain regions: frontal, temporal, parietal and occipital white matter, and the genu, body and splenium of the corpus callosum. The results demonstrated robust age-related differences in diffusion-based indices of cerebral white matter integrity and age-related increase in the WMH volume, but no age differences in the gross regional volumes of the white matter. Hypertension was associated with decline in fractional anisotropy, and exacerbated age differences in fractional anisotropy more than those in the volume of WMH. These findings indicate that of all examined measures, diffusion-based indices of white matter integrity may be the most sensitive indicators of global and regional declines and vascular damage in the aging brain.

Affective symptoms as predictors of Alzheimer's disease in subjects with mild cognitive impairment: a 10-year follow-up study.

BACKGROUND: Affective symptoms are common in subjects with mild cognitive impairment (MCI), but there is disagreement whether these symptoms are predictive for Alzheimer's disease (AD). We investigated the predictive accuracy of affective symptoms for AD during a follow-up study in subjects with MCI, and whether the predictive accuracy was modified by age, the presence of amnestic MCI or the length of follow-up. METHOD: Newly referred subjects (n=263) with MCI older than 55 years were selected from a memory clinic and followed up after 2, 5 and 10 years. Predictors investigated were: symptoms of depression, anxiety, apathy and sleeping problems. RESULTS: Affective symptoms were present in 50-70% of the subjects. The average follow-up period was 5.4 years and 79 subjects (29%) developed AD. Sleeping problems were associated with a decreased risk for AD [odds ratio (OR) 0.35, p<0.001]. Symptoms of depression (OR 0.61, p=0.059) and anxiety (OR 0.58, p=0.051) showed a trend in the same direction. The OR of apathy for AD was 0.67 (p=0.14). Depression was associated with a decreased risk for AD only in subjects without amnestic MCI, but not in subjects with amnestic MCI. Moreover, anxiety was related to the risk for AD differently between subjects diagnosed with AD at the 5-year follow-up (OR 0.23) and subjects diagnosed with AD at the 10-year follow-up (OR 1.7). CONCLUSIONS: Affective symptoms are associated with a decreased risk for AD. The risk may be dependent on MCI subtype or length of follow-up, but it does not depend on age.

Sex differences in self-regulation in early, middle and late adolescence: A large-scale cross-sectional study.

This large-scale cross-sectional study had the aim to investigate whether adolescent males and females differ in self-perceived self-regulation. The large sample size allowed us to investigate sex differences in three age-groups of young (n = 161), middle (n = 133) and late (n = 159) adolescents. Self-regulation was evaluated with a self-report questionnaire, the Amsterdam Executive Functioning Inventory (AEFI). This questionnaire gives a proxi for three executive functions that are important for proper self-regulation: (1) self-control & self-monitoring, (2) attention, and (3) planning & initiative taking. Results revealed clear sex differences in the self-regulation as perceived by mid-adolescents (i.e., 13-16 years). In this age period, females evaluated their attention higher than males, and they reported higher levels of self-control & self-monitoring. Our findings offer important new insights with respect to the decision making, academic achievements and behaviour of 13-16-year olds. Self-regulation is known to have a central role in academic achievement and in behavioural organisation. The sex differences in self-regulation in mid-adolescence may therefore explain part of the difference which males and females in this age-group exhibit in academic achievements and behavioural organisations. The results imply that self-regulation may be a relevant intervention target: rather than focussing on changing behaviour, interventions may focus more on self-insights and thereby changing the adolescent's perceptions about their behaviour. Increased self-insight may have the potency to actually change behaviour, which might be an interesting target for future investigation.

Predictive value of mild cognitive impairment for dementia. The influence of case definition and age.

BACKGROUND/AIMS: In population studies, different mild cognitive impairment (MCI) definitions have been used to predict dementia at a later stage. This study compared predictive values of different MCI definitions for dementia, and the effect of age on the predictive values was investigated. METHODS: This study was conducted as part of an ongoing longitudinal study into the determinants of cognitive aging, the Maastricht Aging Study. RESULTS: MCI best predicted dementia when multiple cognitive domains were considered and subjective complaints were not (sensitivity: 0.66, specificity: 0.78). Age had a strong influence on the sensitivity of MCI for dementia (age 60-70 years: sensitivity = 0.56; age 70-85 years: sensitivity = 0.70). CONCLUSION: The inclusion of multiple cognitive domains and participants aged 70 years and older leads to the best prediction of dementia, regardless of subjective complaints.

Cognition as predictor of current and follow-up depressive symptoms in the general population.

OBJECTIVE: Previous studies have reported an association between depression and poor cognitive functioning. Unknown is to what degree such associations are merely state-related or reflect an enduring depression vulnerability. This study examined whether cognitive deficits predict current and/or follow-up (sub)clinical depressive symptoms in the general population. METHOD: A population-based sample of 569 female twins and 43 of their sisters completed a neuropsychological battery. Cross-sectional and prospective associations between depressive symptoms measured at the subclinical [Symptom Checklist-90 (SCL-90)] and clinical level (Structured Clinical Interview for DSM-IV disorders) and neuropsychological factors (episodic memory and information processing speed) were examined. RESULTS: Structured Clinical Interview for DSM-IV disorders baseline depressive symptoms were significantly associated with information processing speed but not with episodic memory. Episodic memory was significantly associated with follow-up SCL-90 depressive symptoms. CONCLUSION: Being depressed is accompanied by slower information processing. Poor memory functioning may be a predictor for the onset of subclinical depressive symptoms.

Diabetes mellitus type II as a risk factor for depression: a lower than expected risk in a general practice setting.

The aim of the present study was to determine whether a diagnosis of diabetes mellitus (DM) in a primary setting is associated with an increased risk of subsequent depression. A retrospective cohort design was used based on the Registration Network Family Practice (RNH) database. Patients diagnosed with diabetes mellitus at or after the age of 40 and who were diagnosed between 01-01-1980 and 01-01-2007 (N = 6,140), were compared with age-matched controls from a reference group (N = 18,416) without a history of diabetes. Both groups were followed for an emerging first diagnosis of depression (and/or depressive feelings) until January 1, 2008. 2.0% of the people diagnosed with diabetes mellitus developed a depressive disorder, compared to 1.6% of the reference group. After statistical correction for confounding factors diabetes mellitus was associated with an increased risk of developing subsequent depression (HR 1.26; 95% CI: 1.12-1.42) and/or depressive feelings (HR 1.33; 95% CI: 1.18-1.46). After statistical adjustment practice identification code, age and depression preceding diabetes, were significantly related to a diagnosis of depression. Patients with diabetes mellitus are more likely to develop subsequent depression than persons without a history of diabetes. Results from this large longitudinal study based on a general practice population indicate that this association is weaker than previously found in cross-sectional research using self-report surveys. Several explanations for this dissimilarity are discussed

Klinische bruikbaarheid van categoriegebonden woordproductie voor het onderscheiden van dementie en normale cognitieve veroudering.

CATEGORY FLUENCY (ANIMALS, PROFESSIONS) IN NORMAL COGNITIVE AGEING AND DEMENTIA: Regression-based normative data for commonly used semantic verbal fluency test (VFT) scores were derived from data of the Maastricht Aging Study (N=1,825; age range 24-81). Animal naming, profession naming, and the summed score (animal + profession naming) were shown to be profoundly affected by demographical variables, especially age and educational level. The clinical utility of the newly established regression-based VFT norms was evaluated in a large sample of psychogeriatric patients (N=1,063, of which n=890 met the criteria for Alzheimer's or vascular dementia). Results showed that the animal naming VFT score was the most sensitive measure to distinguish normal aging from dementia (when the specificities of the various VFT measures were equated). Fifty patients were found to commit stuck-in-set perseverations, i.e. they generated animal names during test administration of the profession naming VFT. The prevalence of stuck-in-set perseveration was 11.3% in Parkinson dementia and frontal variant frontotemporal dementia, versus 4.6% and 5.3% in dementia of the Alzheimer type and vascular dementia, respectively. Bivariate analyses revealed that people who committed stuck-in-set perseverations were more deficient on a measure of free recall and on several tests of executive control, such as the Expanded Mental Control Test, the Behavioral Dyscontrol Scale and the Alternating Graphical Sequences Test as a measure of response inhibition. Using multivariate logistic regression analysis, only the Alternating Graphical Sequences Test retained an independent effect in the association with stuck-in-set perseveration.

[Category fluency (animals, professions) in normal cognitive ageing and dementia]. / Klinische bruikbaarheid van categoriegebonden woordproductie voor het onderscheiden van dementie en normale cognitieve veroudering.

Regression-based normative data for commonly used semantic verbal fluency test (VFT) scores were derived from data of the Maastricht Aging Study (N=1,825; age range 24-81). Animal naming, profession naming, and the summed score (animal + profession naming) were shown to be profoundly affected by demographical variables, especially age and educational level. The clinical utility of the newly established regression-based VFT norms was evaluated in a large sample of psychogeriatric patients (N=1,063, of which n=890 met the criteria for Alzheimer's or vascular dementia). Results showed that the animal naming VFT score was the most sensitive measure to distinguish normal aging from dementia (when the specificities of the various VFT measures were equated). Fifty patients were found to commit stuck-in-set perseverations, i.e. they generated animal names during test administration of the profession naming VFT. The prevalence of stuck-in-set perseveration was 11.3% in Parkinson dementia and frontal variant frontotemporal dementia, versus 4.6% and 5.3% in dementia of the Alzheimer type and vascular dementia, respectively. Bivariate analyses revealed that people who committed stuck-in-set perseverations were more deficient on a measure of free recall and on several tests of executive control, such as the Expanded Mental Control Test, the Behavioral Dyscontrol Scale and the Alternating Graphical Sequences Test as a measure of response inhibition. Using multivariate logistic regression analysis, only the Alternating Graphical Sequences Test retained an independent effect in the association with stuck-in-set perseveration.

Development of screening guidelines and clinical criteria for predementia Alzheimer's disease. The DESCRIPA Study.

BACKGROUND: There is an urgent need to identify subjects with Alzheimer's disease (AD) in the predementia phase, but validated diagnostic approaches are currently lacking. In this paper, we present the background, design and methods of a study, which aims to develop clinical criteria for predementia AD. We also present baseline characteristics of the subjects included. The study was part of the multicentre DESCRIPA project, which is being conducted within the network of the European Alzheimer's Disease Consortium. METHODS: Clinical criteria will be based on a prospective cohort study of non-demented subjects older than 55 years and referred to a memory clinic. At baseline, a number of markers and risk factors for AD were collected, including demographic variables, measures of performance in activities of daily living, cognitive, neuroimaging and genetic markers, and serum and cerebrospinal fluid markers. Subjects will be reassessed annually for 2-3 years, and we will evaluate which combination of variables best predicts AD-type dementia at follow-up. RESULTS: Between 2003 and 2005, 881 subjects were included from 20 memory clinics. Subjects were on average 70.3 years old, and had 10.4 years of education. The average score on the Mini-Mental State Examination was 27.4.

The association between APOE genotype and memory dysfunction in subjects with mild cognitive impairment is related to age and Alzheimer pathology.

BACKGROUND: Memory problems are a main feature of mild cognitive impairment (MCI) and may be related to the apolipoprotein E (APOE) epsilon4 allele. We investigated whether the effect of the APOE genotype on memory in subjects with MCI was dependent on age and underlying Alzheimer disease (AD) pathology. METHODS: Subjects with MCI (n = 180) were selected from a memory clinic setting. Subjects with at least one APOE epsilon4 allele (n = 83) were compared to non-carriers on several memory measures. Subjects were reassessed 5-10 years later in order to identify those who developed AD. RESULTS: In the middle-aged subgroup, the APOE epsilon4 allele was most strongly related to decreased subjective organization and in the old subgroup to a decreased delayed recall. After excluding subjects with incipient AD (n = 33), results remained similar in the middle-aged subgroup, but in the old subgroup the APOE genotype was no longer associated with memory dysfunction. CONCLUSION: The presence of the APOE epsilon4 allele is associated with impaired memory functioning in both middle-aged and old subjects with MCI, although the memory function affected varies with age. Its effect on memory function may be dependent on underlying AD pathology in elderly subjects, but not in middle-aged subjects.

Serotonin and cognitive flexibility: neuroimaging studies into the effect of acute tryptophan depletion in healthy volunteers.

Cognitive flexibility is the ability to adjust behavior to changes in the environment or task conditions. Previous research suggested that serotonin (5-HT) is involved in cognitive flexibility. Disturbed 5-HT functioning in animals, psychiatric patients and healthy volunteers leads to more rigid behavior. A well recognized method to manipulate levels of brain 5-HT is acute tryptophan depletion (ATD). This method induces a transient and reversible lowering of plasma tryptophan that has been shown to result in decreased brain 5-HT. Only recently has ATD research been combined with functional Magnetic Resonance Imaging (fMRI). In this review, we discuss recent investigations into the effect of ATD on the Blood Oxygen Level Dependent (BOLD) response during tasks that require cognitive flexibility, in healthy volunteers. Functional MRI studies have shown that ATD changes brain activation during tasks that require cognitive flexibility. It is hypothesized that ATD changes the processing of negative feedback, rather than impairing response inhibition, impairing the response to an error or the loss of cognitive control during response interference. Although the results of these studies are intriguing, they are sometimes contradictory. This could be the result of the different paradigms that have been used. Importantly, these studies strongly suggest that future multidisciplinary research should evaluate the mechanisms underlying individual differences and control for variables that have been shown to interact with the effect of ATD on cognitive flexibility and the related brain activation.

Subclinical psychotic experiences and cognitive functioning as a bivariate phenotype for genetic studies in the general population.

OBJECTIVE: Cognitive deficits may be vulnerability markers for the development of schizophrenia. This study examined whether cognitive deficits are related to specific dimensions of subclinical psychotic experiences and whether associations between these variables are caused by additive genetic, common environmental and/or individual-specific environmental factors. METHOD: A general population sample of 298 female twin pairs completed the Community Assessment of Psychic Experiences and a neuropsychological test battery. Associations between subclinical positive and negative psychotic dimensions and neuropsychological factors (episodic memory and information processing speed) were examined. Univariate correlation and structural equation analyses were performed to explore the role of genetic and environmental factors in the phenotypes separately. Bivariate correlation and structural equation analyses were applied to examine the causes of association. RESULTS: There were significant correlations between information processing speed and both the positive (r=.11; p<.05) and the negative dimension (r=.10; p<.05). For the negative dimension and for speed of processing, the data suggested a model that included genetic factors. The observed phenotypic correlation between the negative dimension and information processing speed could be solely explained in terms of additive genetic factors. Although the comparison of the correlations for MZ and DZ pairs did not give a clear indication as to the underlying causes of the association, structural equation modelling suggested that the observed phenotypic correlation between the negative dimension and information processing speed could be solely explained in terms of additive genetic factors. CONCLUSION: Negative symptoms and information processing speed are associated at the subclinical level and this association appears to be influenced by genetic factors exclusively. Bivariate psychosis phenotypes may represent suitable candidates for molecular genetic studies in the general population.

Exploratory study into the relation between plasma phospholipid fatty acid status and cognitive performance.

Previous research found a negative association between DHA status and selective attention in pregnant women. Goal of the present exploratory study is to investigate the potential relationship between essential fatty acid status and cognitive performance in a healthy non-pregnant population. Cognitive performance of 54 non-pregnant women was determined at baseline, 3, 15, and 22 weeks later with an objective neurocognitive test battery covering different brain domains. Plasma phospholipid fatty acid status was determined at baseline and at 22 weeks. The fatty acids of primary interest (arachidonic acid, adrenic acid, Osbond acid, eicosapentaenoic acid, and docosahexaenoic acid) were no significant predictors of cognitive performance at baseline or 22 weeks later. However, they attributed significantly (26.3%) to the amount of explained variance of the learning effect on the Stroop task, measuring general speed of information processing. Higher docosahexaenoic acid levels were associated with a slower learning curve. For arachidonic acid the opposite was found. In conclusion, this study provides a preliminary indication that a higher DHA status might be associated with slower learning curves. However, additional studies are necessary.

Cognitive functioning in healthy older adults aged 64-81: a cohort study into the effects of age, sex, and education.

The objective of this study was to determine a possible differential effect of age, education, and sex on cognitive speed, verbal memory, executive functioning, and verbal fluency in healthy older adults. A group of 578 healthy participants in the age range of 64-81 was recruited from a large population study of healthy adults (Maastricht Aging Study). Even in healthy individuals in this restricted age range, there is a clear, age-related decrease in performance on executive functioning, verbal fluency, verbal memory, and cognitive speed tasks. The capacity to inhibit information is affected most. Education had a substantial effect on cognitive functioning: participants with a middle or high level of education performed better on cognitive tests than did participants with a low level of education. Women performed better than men on verbal memory tasks. Therefore, education and sex must be taken into account when examining an older individual's cognitive performance.

[Development of memory clinics in The Netherlands]. / Geheugenpoli's in Nederland: Ontwikkelingen sinds 1998.

AIM: Memory Clinics (MC's) are multidisciplinary teams involved with early diagnosis and treatment of people with dementia. In order to attain more insight into the development of this kind of services in The Netherlands, we compared the data of two inventories, one of 1998 and the other of 2004. RESULTS: The number of MC's increased from 12 to 40. The number of referrals per service has also increased. Dementia was the most important syndromal diagnosis. The focus is less exclusively on academic centres. An growing number of MC's has structural collaborations with local service providers for mental health. Differences among MC's exist with regard to the number of referrals per week, the intensity and duration of the diagnostic procedures and the proportion of people without dementia. There is much interest among MC's to participate in a national network for harmonisation and quality control. CONCLUSION: MC's are an increasing part of standard care for people with early dementia and other cognitive disorders.

Prevalence of primitive reflexes and the relationship with cognitive change in healthy adults: a report from the Maastricht Aging Study.

OBJECTIVES: Primitive reflexes (PR) generally disappear early in life but may reappear later, in which case they are often associated with chronic neurological conditions, such as dementia or Parkinson's disease. Studies have shown that the presence of PRs may be indicative of both the severity and rate of progression of these diseases and may be the result of disinhibition of cortical networks. The association between PRs and cognitive function in usual ageing is unclear. We investigated whether the occurrence, amplitude, and persistence of four nociceptive (glabbelar tap, palmomental, pollicomental, and snout reflexes), three prehensile reflexes (suck, palmar grasp, and rooting), and two other reflexes (mouth open finger-spread and nuchocephalic reflexes) were related to performance in specific cognitive domains in normal ageing individuals. METHODS: Four-hundred and seventy normal aging participants (25-82 years) in the Maastricht Aging Study (MAAS), were included in the study. They were neurologically and cognitively screened at baseline and were retested after 3 (only individuals aged 50 years and older at baseline) and 6 years. RESULTS: The prevalence of most PRs increased with age: 47% of men aged 25-45 years had at least one PR, compared with 73% of men aged 65-85 year (p = 0.002). In women these percentages were 51 and 75, respectively (p=0.008). The prevalence, amplitude, and persistence of PRs were unrelated to cognition at baseline or at the 3- or 6-year follow-up. CONCLUSIONS: The prevalence of particularly nociceptive reflexes rises substantially with increasing age in normal individuals. However, the presence of PRs cannot be considered to be a marker of cognitive decline in normal aging individuals.

Ambulatory blood pressure, asymptomatic cerebrovascular damage and cognitive function in essential hypertension.

Prolonged exposure to elevated blood pressure (BP) can lead to both structural (white matter lesions (WML) or infarctions) and functional changes in the brain. We studied in previously diagnosed essential hypertensive individuals if diurnal BP variation and ambulatory BP (ABP) profile (daytime, night time and 24-h BP averages) were related to evidence of WML, the presence of 'silent' infarcts, and cognitive performance. A group of 86 patients (mean age 57.4+/-10 years, range 40-80) were first screened for hypertension-related organ damage and underwent 24-h ABP monitoring, magnetic resonance imaging (MRI) of the brain, and a comprehensive neurocognitive assessment. Age and ABP profile were related to more periventricular, but not subcortical, WML and to presence of lacunar infarctions on MRI. After correction for demographical group differences, no association was found between night time dipping of BP on the one hand and both WML load and cognitive parameters (verbal memory, sensorimotor speed, cognitive flexibility) on the other. The presence of lacunar infarctions, however, predicted lower performance on verbal memory. Furthermore, daytime and 24-h pulse pressure averages were associated with pWML, whereas systolic BP and mean arterial pressure (MAP) for daytime, night-time and 24-h periods were higher in patients with lacunar infarctions. Notwithstanding the large variability of WML in this sample, the evidence of a connection between diurnal BP variation and early target organ damage in the brain was not convincing. However, the ABP profile may be predictive of cerebral lesion type.