Biomedical subjects

Gerry Jager

Publications and source records attributed to Gerry Jager.

9 recordsLinked to original sources

PubMed2026

The combined and independent influence of food texture and a 'mindful eating' instruction on eating rate and food intake among Dutch primary schoolchildren.

Eating rate (ER), the amount of food consumed per unit of time, is a key determinant of food intake, with faster ER associated with larger meal size. Research in adults has shown that both sensory properties like texture, and instructions can influence ER and intake. However, their independent and combined effect on ER and intake in children remain poorly understood. This study examined the effects of food texture and a 'mindful eating' instruction on ER and food intake in children. Children (N = 73), 38 boys, aged 4-12 years, participated in a 4-week cluster-randomized incomplete cross-over study conducted during regular school lunches. Using a 2×3 factorial design, children were exposed to two levels of food texture (softer vs. harder whole-grain buns) and three types of instructions (none, control, 'mindful'). Linear mixed models with repeated measures were used, adjusting for sex and group. As the interaction between food-texture and type of instructions was non-significant, it was excluded from the final models. Results revealed a strong main effect of food texture on ER and food intake (all p < 0.001), where compared with softer buns, harder buns were associated with a slower eating rate (Δ = -6.67 g/min, SE = 0.59) and reduced food intake (Δ = -70 g, SE = 8). In contrast, type of instruction had no significant effect on ER or intake (p = 0.85). Our findings demonstrate that food texture exerts a dominant influence on children's eating rate and food intake, highlighting texture modification as a potential leverage point for influencing ER and intake in children.

Humans↗

PubMed2026

Determinants of Meal Satisfaction and Their Association With Childhood Obesity: A Systematic Review.

Meal satisfaction is considered a multidimensional concept that includes sensory enjoyment, cognitive, emotional, and physiological components and relates to contentment with the meal experience as a whole. However, its relevance to eating behavior and body weight remains unclear, especially in children. The present review investigated the potential relationship between meal satisfaction-related constructs and childhood obesity, and whether this relation is shaped by individual factors and the external environment. Seventeen eligible studies from 350 records published between 2008 and 2024 were included. No study directly assessed meal satisfaction; instead, proxy measures were used. Food enjoyment emerged as the proxy most consistently associated with BMI, often clustering with higher food responsiveness, lower satiety responsiveness, and emotional overeating. Parental feeding practices, especially pressure to eat, significantly contributed to variation in children's eating behavior and were associated with lower food enjoyment. Overall, meal satisfaction could be a key aspect to consider in childhood obesity prevention programs. However, to date, the available evidence is heterogeneous and predominantly observational. Future longitudinal and intervention studies are needed, alongside child-appropriate instruments to objectively quantify food satisfaction in children. Research that helps understand the role of contextual eating factors on children's meal satisfaction and eating behavior is also warranted.

Humans↗

PubMed2006

Effects of frequent cannabis use on hippocampal activity during an associative memory task.

Interest is growing in the neurotoxic potential of cannabis on human brain function. We studied non-acute effects of frequent cannabis use on hippocampus-dependent associative memory, investigated with functional Magnetic Resonance Imaging (fMRI) in 20 frequent cannabis users and 20 non-users matched for age, gender and IQ. Structural changes in the (para)hippocampal region were measured using voxel-based morphometry (VBM). Cannabis users displayed lower activation than non-users in brain regions involved in associative learning, particularly in the (para)hippocampal regions and the right dorsolateral prefrontal cortex, despite normal performance. VBM-analysis of the (para)hippocampal regions revealed no differences in brain tissue composition between cannabis users and non-users. No relation was found between (para)hippocampal tissue composition and the magnitude of brain activity in the (para)hippocampal area. Therefore, lower brain activation may not signify neurocognitive impairment, but could be the expression of a non-cognitive variable related to frequent cannabis use, for example changes in cerebral perfusion or differences in vigilance.

Adult↗

PubMed2006

A prospective cohort study on sustained effects of low-dose ecstasy use on the brain in new ecstasy users.

It is debated whether ecstasy use has neurotoxic effects on the human brain and what the effects are of a low dose of ecstasy use. We prospectively studied sustained effects (>2 weeks abstinence) of a low dose of ecstasy on the brain in ecstasy-naive volunteers using a combination of advanced MR techniques and self-report questionnaires on psychopathology as part of the NeXT (Netherlands XTC Toxicity) study. Outcomes of proton magnetic resonance spectroscopy (1H-MRS), diffusion tensor imaging (DTI), perfusion-weighted imaging (PWI), and questionnaires on depression, impulsivity, and sensation seeking were compared in 30 subjects (12M, 21.8+/-3.1 years) in two sessions before and after first ecstasy use (1.8+/-1.3 tablets). Interval between baseline and follow-up was on average 8.1+/-6.5 months and time between last ecstasy use and follow-up was 7.7+/-4.4 weeks. Using 1H-MRS, no significant changes were observed in metabolite concentrations of N-acetylaspartate (NAA), choline (Cho), myo-inositol (mI), and creatine (Cr), nor in ratios of NAA, Cho, and mI relative to Cr. However, ecstasy use was followed by a sustained 0.9% increase in fractional anisotropy (FA) in frontoparietal white matter, a 3.4% decrease in apparent diffusion (ADC) in the thalamus and a sustained decrease in relative regional cerebral blood volume (rrCBV) in the thalamus (-6.2%), dorsolateral frontal cortex (-4.0%), and superior parietal cortex (-3.0%) (all significant at p<0.05, paired t-tests). After correction for multiple comparisons, only the rrCBV decrease in the dorsolateral frontal cortex remained significant. We also observed increased impulsivity (+3.7% on the Barratt Impulsiveness Scale) and decreased depression (-28.0% on the Beck Depression Inventory) in novel ecstasy users, although effect sizes were limited and clinical relevance questionable. As no indications were found for structural neuronal damage with the currently used techniques, our data do not support the concern that incidental ecstasy use leads to extensive axonal damage. However, sustained decreases in rrCBV and ADC values may indicate that even low ecstasy doses can induce prolonged vasoconstriction in some brain areas, although it is not known whether this effect is permanent. Additional studies are needed to replicate these findings.

Adolescent↗

PubMed2006

Long-term effects of frequent cannabis use on working memory and attention: an fMRI study.

RATIONALE: Excessive use of cannabis may have long-term effects on cognitive abilities. Mild impairments have been found in several cognitive domains, particularly in memory and attention. It is not clear, however, whether these effects also occur with moderate, recreational use of cannabis. Furthermore, little is known about underlying brain correlates. OBJECTIVES: The aim of this study is to assess brain function in frequent but relatively moderate cannabis users in the domains of working memory and selective attention. METHODS: Functional magnetic resonance imaging was used to examine verbal working memory and visuo-auditory selective attention in ten frequent cannabis users (after 1 week of abstinence) and ten non-using healthy controls. Groups were similar in age, gender and estimated IQ. RESULTS: Cannabis users and controls performed equally well during the working memory task and the selective attention task. Furthermore, cannabis users did not differ from controls in terms of overall patterns of brain activity in the regions involved in these cognitive functions. However, for working memory, a more specific region-of-interest analysis showed that, in comparison to the controls, cannabis users displayed a significant alteration in brain activity in the left superior parietal cortex. CONCLUSION: No evidence was found for long-term deficits in working memory and selective attention in frequent cannabis users after 1 week of abstinence. Nonetheless, frequent cannabis use may affect brain function, as indicated by altered neurophysiological dynamics in the left superior parietal cortex during working memory processing.

Adult↗

PubMed2006

Ecstasy use and self-reported depression, impulsivity, and sensation seeking: a prospective cohort study.

Although there are indications that ecstasy users have higher levels of depression, impulsivity, and sensation seeking, it is unknown whether these are consequences of ecstasy use or predisposing factors for starting ecstasy use. We prospectively assessed the predictive value of depression, impulsivity, and sensation seeking on future first time ecstasy use. We also assessed whether depression, impulsivity, and sensation seeking had changed after first ecstasy use. Depression, impulsivity, and sensation seeking were assessed using self-report questionnaires in 188 ecstasy-naive volunteers with high probability for future ecstasy use. After a mean follow-up of 17 months, measurements were repeated in 59 incident ecstasy users (mean 6.0 tablets) and 61 matched persistent ecstasy-naive volunteers. Only experience seeking (subscale of the sensation seeking scale) predicted future ecstasy use (OR -- 1.05, 95% CI 1.00 to 1.10), but after adjustment for potential confounders this was not significant anymore. At follow-up, significant effects of ecstasy use on the general and the disinhibition subscale of the sensation seeking scale were observed (after adjustment for potential confounders: regression coefficient B 0.51, 95% CI 0.20 to 0.83 and B -- 3.25, 95% CI 1.74 to 4.76, respectively). These data indicate that depression, impulsivity, and sensation seeking do not predict first time ecstasy use in a population of young adults with the intention to start using ecstasy and that low level ecstasy use does not seem to cause depression or impulsivity. However, low level ecstasy use may increase (certain aspects of) sensation seeking.

Adolescent↗

PubMed2005

The Netherlands XTC Toxicity (NeXT) study: objectives and methods of a study investigating causality, course, and clinical relevance.

This paper describes the objectives and methods of The Netherlands XTC Toxicity (NeXT) study focussing on the causality, course, and clinical relevance of ecstasy neurotoxicity. Previous studies suggest that ecstasy (3,4 methylene-dioxymethamphetamine, MDMA, XTC) is toxic toward brain serotonin axons, but most of these studies have serious methodological limitations. The current study is a combination of different approaches with three substudies: (1) a crosssectional substudy among heavy ecstasy users and controls with variation in drug use, which will provide information about potential neurotoxic consequences of ecstasy in relation to other drugs; (2) a prospective cohort substudy in ecstasy-naive subjects with high risk for future ecstasy use, which will provide information on the causality and short-term course of ecstasy use and potential neurotoxicity, and (3) a retrospective cohort substudy in lifetime ecstasy users and matched controls of an existing epidemiological sample that will provide information on long-term course and outcome of ecstasy use in the general population. Neurotoxicity is studied using (a) different imaging techniques (beta-CIT SPECT, 1H-MR spectroscopy, diffusion tensor imaging, perfusion weighted imaging and functional magnetic resonance imaging), and (b) neuropsychological and psychiatric assessments of memory, depression, and personality. The combined results will lead to conclusions that can be used in prevention messages, clinical decision making, and the development of an (inter)national ecstasy policy.

Adolescent↗

PubMed2004

Sex differences for selective forms of spatial memory.

In the present study, a systematic comparison of sex differences for several tests of spatial memory was conducted. Clear evidence for more accurate male performance was obtained for precise metric positional information in a wayfinding task and in an object location memory task. In contrast, no sex difference characterized topological information processing (object-to-position assignment). Together, these findings provide further insight in the specificity of sex differences in spatial memory and in the functional architecture of spatial memory. Implications for the relevant evolutionary basis are discussed.

Adult↗

PubMed2003

On the hemispheric specialization for categorical and coordinate spatial relations: a review of the current evidence.

This article reviews current evidence on the hemispheric specialization hypothesis for two types of spatial relations representations; categorical versus coordinate [Psychol. Rev. 94 (1987) 148; J. Exp. Psychol.: Percept. Perform. 15 (1989) 723]. Categorical representations capture general properties of the spatial structure of a visual stimulus, without defining the exact metric properties. Coordinate representations specify precise spatial locations of objects or parts in terms of metric units. It is claimed that a hemispheric difference in contribution to the computation of both types of spatial relations representations exists, in which the left hemisphere is specialized for the computation of categorical spatial representations while the right hemisphere is specialized for the computation of coordinate ones. Several forms of research (experimental, computer simulations, patient studies and neuroimaging studies) are reviewed. In general, there is convergent evidence for a conceptual separation of coordinate and categorical processing, with strongest indications for a relative right hemisphere advantage in encoding coordinate spatial relations, and weaker support for left hemispheric categorical specialization. The pattern appears to be critically linked to receptive field properties of the two hemispheres and as such is modulated by certain elementary visual characteristics of the displayed stimuli.

Brain Diseases↗