Sweet and sour sips: No effect of repeated exposure to sweet or sour-tasting sugary drinks on children's sweetness preference and liking.

Health agencies advocate reducing children's sweetness exposure to lower sweetness preference or liking to ultimately lower sugar intake. However, the relationship between sweetness exposure, preference, and liking remains unclear. This work investigated the influence of exposure to a sucrose-containing sweet or sour-tasting drink on sweetness preference and liking for sweet and sour products in 4-7-year-old children (n = 65). The children were randomized into three groups with one daily exposure to either the sweet drink, sour drink, or water (control group) for 14 days. Sweetness preference was assessed at baseline (t1), day 15 (t2), and two months after the intervention (t3), using a forced-choice, paired comparison test with five beverages varying in sweetness intensity. Hedonic liking for the intervention drinks, a sweet and sour yogurt, and a sweet and sour candy was evaluated using a 5-point pictorial scale. Linear mixed models revealed a significant increase in sweetness preference from t1 to t3 (F(2) = 7.46, p < 0.001). However, ANCOVA analysis indicated that this effect was not caused by the intervention. Based on linear mixed models, we observed that children's hedonic liking for sweet and sour products remained stable from t1 to t3 and was not influenced by the intervention. These findings suggest that 14 exposures to a sucrose-containing sweet or sour-tasting drink did not affect sweetness preference or liking in 4-7-year-old children.

The Baby's First Bites RCT: Evaluating a Vegetable-Exposure and a Sensitive-Feeding Intervention in Terms of Child Health Outcomes and Maternal Feeding Behavior During Toddlerhood.

BACKGROUND: Parenting interventions during the first years of life on what and/or how to feed infants during complementary feeding can promote healthy eating habits. OBJECTIVES: An intervention promoting repeated exposure to a variety of vegetables [repeated vegetable exposure (RVE); what] and an intervention promoting responding sensitively to child signals during mealtime [video-feedback intervention to promote positive parenting-feeding infants (VIPP-FI); how] were compared, separately and combined (COMBI), with an attention control condition (AC). Primary outcomes were vegetable consumption and self-regulation of energy intake; secondary outcomes were child anthropometrics and maternal feeding practices (sensitive feeding, pressure to eat). METHODS: Our 4-arm randomized controlled trial included 246 first-time Dutch mothers and their infants. Interventions started when infants were 4-6 mo old and ended at age 16 mo. The present study evaluated effects at 18 (t18) and 24 (t24) mo of age. Vegetable acceptance was assessed using three 24-h dietary recalls, self-regulation of energy intake by an eating-in-the-absence-of-hunger experiment and mother-report, and maternal feeding behavior by observation and mother-report. RESULTS: Linear mixed model and ANOVA analyses revealed no follow-up group differences regarding child vegetable intake or self-regulatory behavior. The proportion of children with overweight was significantly lower in the COMBI group, compared with the VIPP-FI group at t18 (2% compared with 16%), and with the AC group at t24 (7% compared with 20%), although this finding needs to be interpreted cautiously due to the small number of infants with overweight and nonsignificant effects on the continuous BMI z-score measure (P values: 0.29-0.82). Finally, more sensitive feeding behavior and less pressure to eat was found in the VIPP-FI and COMBI groups, compared with the RVE and AC groups, mostly at t18 (significant effect sizes: d = 0.23-0.64). CONCLUSIONS: Interventions were not effective in increasing vegetable intake or self-regulation of energy intake. Future research might usefully focus on risk groups such as families who already experience problems around feeding.This trial is registered at clinicaltrials.gov as NCT03348176.

The sweet tooth of infancy: Is sweetness exposure related to sweetness liking in infants up to 12 months of age?

Infants become increasingly exposed to sweet-tasting foods in their first year of life. However, it is still unclear whether repeated exposure to sweet taste is linked to infants' sweetness liking during this period. Making use of data from the OPALINE cohort, this study aimed to examine the link between sweetness exposure and sweetness liking during two important periods in early infant feeding: at the start of complementary feeding (3-6 months) and the transition to the family table (10-12 months). Infants' sweetness exposure was assessed using 7-d food records which were completed by mothers every month (n 312), reporting daily consumption rates of formula/breast milk or complementary food and the type of formula milk and/or complementary foods for each feeding occasion. Infants' sweetness liking was studied in the laboratory at 3, 6 and 12 months of age by assessing their response to a lactose-water solution and the amount drunk of this solution compared with plain water. Linear regressions and structural equation model assessed associations between exposure to and liking for sweetness at 6 and 12 months. Neither at 6 (n 182) nor at 12 months (n 197) was sweetness exposure associated with sweetness liking. While sweetness liking at 3 months was unrelated to liking at 6 months, the latter predicted sweetness liking at 12 months. These findings demonstrate no association between sweetness exposure at 3 to 12 months and liking at 6 and 12 months despite a sharp increase in sweetness exposure in that period. However, sweetness liking at 6 and 12 months was positively associated.

To like or not to like: Negotiating food assessments of children from families with a low socioeconomic position.

The present study explored how primary school-aged children from families with a low socioeconomic position produce 'likes' and 'dislikes' of foods during everyday family meals, and how these (dis)likes are understood and treated by their parents. It is crucial to understand how food preferences develop in the course of everyday life, as it is known that there are socioeconomic disparities in food preference and consumption, and that children from families with a low socioeconomic position have relatively poorer diets. Deploying an interactional approach to food preference, video recordings of 79 evening meals in families with a low socioeconomic position were analyzed using discursive psychology and conversation analysis. The analysis highlighted that children's food likes and dislikes were treated differently by their parents. While likes were routinely not responded to, agreed with or further elaborated, dislikes were predominantly oriented to as food refusals or treated as inappropriate, or non-genuine claims. Children's food assessments, i.e., likes and dislikes, were often disattended by parents when they appeared to be food preference displays. By contrast, assessments that accomplished social actions like refusals and complaints were more often responded to. The analysis also revealed the importance of distinguishing between assessments about food items in general, that were not currently being eaten, and assessments of food eaten here-and-now. All in all, the study evidences that and how assessment sequences open up interactional spaces where children and parents orient to and negotiate relative rights and responsibilities to know, to assess and to accomplish specific actions. Implications for food preference research are discussed.

Healthy eating beliefs and the meaning of food in populations with a low socioeconomic position: A scoping review.

Profound understanding of healthy eating beliefs in populations with a low socioeconomic position (SEP) can benefit attempts to improve diet quality in this population, but literature on this subject is fragmented. The purpose of this scoping review was to systematically map healthy eating beliefs and the meaning of food and eating in populations with a low SEP. Systematic search of electronic databases yielded 35 relevant publications that were included in a qualitative synthesis. Populations with a low SEP perceived healthy eating as important, although they expressed various meanings of 'healthy' and 'good' eating. Lack of time and money posed perceived barriers to healthy eating, as well as social influences, and desired identities that can be expressed by specific foods. Traditions were important influences on food and eating practices. Eating behavior was perceived as one's own responsibility and desirably within one's own control. Parents expressed the role of food to regulate children's (eating) behavior. In conclusion, perceived limited control over what is eaten due to various barriers as described by populations with a low SEP, may also be viewed as competing values. Deeper understanding of reasons and thoughts underlying healthy eating beliefs and what it means to eat 'well' is largely lacking in this domain. The findings call for an in-depth exploration of the origin and construction of beliefs regarding 'healthy' and 'good' eating in populations with a low SEP.

Colouring perception: Package colour cues affect neural responses to sweet dairy drinks in reward and inhibition related regions.

Extrinsic product cues such as package colour may change product perception and perceived reward value during product evaluation. Healthier foods (i.e., 'light', sugar- or fat-reduced) often have different packages than regular products, e.g., they may be less vibrantly coloured. People vary in their degree of health-interest and self-control ability and may be affected differently by package colour. This study assesses the extent to which package colour and participant characteristics interact and influence product perception and brain responses. Thirty-four healthy females performed a functional MRI task in which they viewed four differently coloured packages (regular vs. healthier; differing in brightness and saturation levels) with or without simultaneously tasting a either a regular or a healthier calorie-reduced drink. Results indicate main effects of package and taste and a package*taste interaction effect. Compared to healthier packages viewing regular packages enhanced activation in region implicated in inhibitory control (inferior frontal gyrus) and a reward-related region (striatum), the latter even more so as participants' health interest increased (r = 0.43, p = 0.01). Incongruent package-taste combinations decreased activation in the orbitofrontal cortex (OFC, a region implicated in reward representation) compared to congruent combinations. Tasting the healthier compared to regular product enhanced activation in the middle and superior frontal gyrus, which are implicated in inhibitory control, as well as the striatum and OFC, suggesting a cognitively driven preference for the healthier product. In conclusion, this paper provides evidence for the conditions under which package colour and taste properties modulate neural correlates related to reward and inhibition. Individual differences in health-interest and impulsivity influence package- and taste-related neural correlates and thus underscore the importance of taking participant characteristics into account in food research.

Breast-feeding duration and child eating characteristics in relation to later vegetable intake in 2-6-year-old children in ten studies throughout Europe.

OBJECTIVE: Breast-feeding is thought to facilitate young children's acceptance of new foods, including vegetables, but the evidence for this relationship appears inconsistent across studies. Increasing children's vegetable intake remains challenging; therefore the present study aimed to investigate whether breast-feeding duration predicts vegetable intake in 2-6-year-old children. DESIGN: Actual vegetable intake was measured in studies across three European countries. General linear model analyses with breast-feeding duration, sex and age of the child and maternal education as variables were used to predict children's vegetable intake per country. Additionally, the relationships between child eating behaviour characteristics (asked through the Child Eating Behaviour Questionnaire) and vegetable intake were investigated via Pearson correlations. SETTING: Daycare centres, schools and home settings in Denmark, Greece and the Netherlands. SUBJECTS: Children aged 2-6 years (n 750). RESULTS: Breast-feeding duration was positively associated with children's vegetable intake at 2-6 years old in Denmark (P<0·01) and the Netherlands (P<0·05), but not in Greece (P=0·17). Age of the child, maternal education and sex of the child did not predict vegetable intake in our sample. All countries showed an inverse relationship between food neophobia and children's vegetable intake and a positive relationship between vegetable liking and intake. CONCLUSIONS: The present study found that breast-feeding duration is a predictor of later vegetable intake, but that current child eating behaviour characteristics, such as vegetable liking, food neophobia and enjoyment of food, also influence vegetable intake. Besides encouragement of breast-feeding duration, strategies that support vegetable liking and food enjoyment and decrease food neophobia are needed to support young children's vegetable intake.

Cheers, proost, saúde: Cultural, contextual and psychological factors of wine and beer consumption in Portugal and in the Netherlands.

Wine and beer consumption are an integral part of European culture: Southern Europe is associated with wine and Northern Europe is associated with beer. When consumed in moderation, these alcoholic beverages can be part of a balanced and healthy diet. In the 1990s, non-alcoholic beer (NAB), which has no cultural roots, became available in the market. This review identifies determinants for consumption of wine, beer, and NAB, using data on consumption patterns from Portugal and the Netherlands. Since the 1960s the image of Portugal as a wine country declined, whereas the image of the Netherlands as a beer country remained stable. In each country beer is now the most consumed alcoholic beverage and is mainly a men's beverage, whereas wine is the second most consumed and is consumed by both genders. Cultural differences define Portuguese as "outdoors, everyday drinkers", within a meal context, and Dutch as "at home, weekend drinkers." Wine is perceived as the healthiest beverage, followed by NAB, and regular beer. Motivation for consumption is related to context: wine for special occasions, beer for informal occasions, and NAB for occasions when alcohol is not convenient. Moderate wine and beer consumption seems to be surrounded by positive emotions. This review is relevant for public health, for industry market strategies, and identifies opportunities of future research on drinking behaviour.

Exploring the functional mealtime associations of older adults through consumer segmentation and a means-end chain approach.

Senior consumers are a rapidly growing and highly heterogeneous part of the world's population. This group does not always meet its recommended protein intake, which can negatively impact on their physical functioning and quality of life. To date, little is known about their motivations to consume protein-rich meals. In the current study, we therefore aim to identify consumer segments within the group of vital community-dwelling older adults on the basis of mealtime functionality (for example 'I eat because I'm hungry', or 'I eat because it is cosy'). To this end, we first conducted an online survey to identify these functional mealtime expectations of older consumers (study I, n = 398, 158 males, mean age 65.8 (y) ± 5.9 (SD)). To obtain further insights regarding mealtime functionality and proteins/protein enrichment, laddering interviews were conducted with a subgroup of the segmentation study participants (study II, n = 40, 20 males, mean age 66.9 (y) ± 4.8 (SD)). The results of the online survey showed three consumer clusters: cosy socialisers, physical nutritioners, and thoughtless rewarders. Thoughtless rewarders tend to eat without having explicit thoughts about it, they eat for the reward, and score highest on environmental awareness. Both the segmentation and the in-depth interviews showed that, for the cosy socialisers, the cosiness and social function of a meal are important motivators, whereas for the physical nutritioners the focus is more on the health and nutrient aspects of a meal. For cosy socialisers, protein enrichment can best be achieved through addition of protein-rich ingredients, whereas, for physical nutritioners, addition of protein powder is preferred. These results provide practical guidelines for the development of protein-rich meals and communication strategies tailored to the needs of specific vital community-dwelling older subgroups.

Influence of choice on vegetable intake in children: an in-home study.

Children's vegetable consumption is still far below that recommended, and stimulating their intake is a challenge for caregivers. The objective of this study was to investigate whether choice-offering is an effective strategy to increase children's vegetable intake in an in-home situation. Seventy children (mean age 3.7; SD 1) randomly assigned to a choice or a no-choice condition, were exposed 12 times to six familiar target vegetables at home during dinner. In the choice group, two selected vegetables were offered each time, whereas the no-choice group only received one vegetable. Vegetable intake was measured by weighing children's plates before and after dinner. A mixed linear model with age, gender, and baseline vegetable liking as covariates was used to compare intake between the choice and the no-choice group. Mixed linear model analysis yielded estimated means for vegetable intake of 48.5 g +/- 30 in the no-choice group and 57.7 g +/- 31 for the choice group (P = 0.09). In addition, baseline vegetable liking (P <0.001) and age (P = 0.06) predicted vegetable intake to be higher when the child liked vegetables better and with older age. These findings suggest that choice-offering has some, but hardly robust, effect on increasing vegetable intake in children. Other factors such as age and liking of vegetables also mediate the effect of offering a choice.

That's why I take my ONS. Means-end chain as a novel approach to elucidate the personally relevant factors driving ONS consumption in nutritionally frail elderly users.

Oral nutritional supplements (ONS) are a recommended form of nutritional intervention for older malnourished persons when a 'food first' approach and/or food fortification prove ineffective. The efficacy of ONS will depend on, amongst other factors, whether persons do, or do not, consume their prescribed amount. Factors influencing ONS consumption can be product, context, or person related. Whereas product and context have received some attention, little is known about the person factors driving ONS consumption. In addition, the relative importance of the product, context, and person factors to ONS consumption is not known. Using the means-end chain (MEC) method, the current study elucidated personally relevant factors (product, context, and person factors) related to ONS consumption in two groups of older nutritionally frail ONS users: community-dwelling persons and care home residents with mainly somatic disorders. To our knowledge, the current work is the first to apply the MEC method to study older nutritionally frail ONS users. Forty ONS users (n = 20 per group) were recruited via healthcare professionals. The level of frailty was assessed using the FRAIL scale. Both groups were interviewed for 30 to 45 minutes using the soft laddering technique. The laddering data were analysed using LadderUX software™. The MEC method appeared to work well in both groups. The majority of the participants took ONS on their doctor's or dietician's prescription as they trusted their advice. The community-dwelling group took ONS to prolong their independence, whereas the care home group reported values that related more to small improvements in quality of life. In addition, care home residents perceived themselves as dependent on their caregiver for their ONS arrangements, whereas this dependence was not reported by community-dwelling persons. Key insights from this work will enable doctors and dieticians to customize their nutritional interventions to ONS users' personal needs and thus positively impact health outcomes.

The endocannabinoid system and appetite: relevance for food reward.

Mounting evidence substantiates the central role of the endocannabinoid system (ECS) in the modulation of both homeostatic and hedonic elements of appetite and food intake. Conversely, feeding status and dietary patterns directly influence activity of the ECS. Following a general introduction on the functioning of the ECS, the present review specifically addresses its role in the modulation of hedonic eating. Humans possess strong motivational systems triggered by rewarding aspects of food. Food reward is comprised of two components: one appetitive (orienting towards food); the other consummatory (hedonic evaluation), also referred to as 'wanting' and 'liking', respectively. Endocannabinoid tone seems to influence both the motivation to feed and the hedonic value of foods, probably by modifying palatability. Human physiology underlying hedonic eating is still not fully understood. A better understanding of the role of the ECS in the rewarding value of specific foods or diets could offer new possibilities to optimise the balance between energy and nutrient intake for different target groups. These groups include the obese and overweight, and potentially individuals suffering from malnutrition. Examples for the latter group are patients with disease-related anorexia, as well as the growing population of frail elderly suffering from persistent loss of food enjoyment and appetite resulting in malnutrition and involuntary weight loss. It has become clear that the psychobiology of food hedonics is extremely complex and the clinical failure of CB1 inverse agonists including rimonabant (Accomplia®) has shown that 'quick wins' in this field are unlikely.

Food choice: the battle between package, taste and consumption situation.

The present study compared how intrinsic (sensory) and extrinsic (packaging) product properties influence actual food choice in combination with the concept of product appropriateness in a specific consumption context. Food choice of seven test products was measured in three breakfast sessions within a simulated cafeteria setting with subsequent product consumption. Test products were five breakfast drinks and two dessert products considered as inappropriate for breakfast. One hundred and three participants took part in a blind taste session, after which they chose one out of the seven foods to consume for breakfast. In a second session (familiar package session), the same participants based their choice on the package of the seven foods they tasted in the first session. An additional group of 65 participants took part in a third naïve package session, where they chose just on the basis of package without being previously exposed to the foods. Results showed that food choices in the naïve package session were guided by the package that labelled the products as "breakfast product". Food choices in the blind session were strongly correlated (r = 0.8) with the liking of the products. Food choice in the "familiar package session" lay between the blind and naïve package session. It is concluded that food choice in a simulated cafeteria setting is guided by extrinsic (package) as well as intrinsic (sensory) properties and both can act as a cue for product appropriateness given a specific consumption context. Depending on the salience of either intrinsic or extrinsic properties during the choice moment their impact on choice is stronger.

It is not just a meal, it is an emotional experience - a segmentation of older persons based on the emotions that they associate with mealtimes.

Worldwide, the group of older persons is growing fast. To aid this important group in their food and meal requirements, a deeper insight into the expectations and experiences of these persons regarding their mealtimes and snack times is needed. In the current study, we aim to identify consumer segments within the group of vital community-dwelling older persons on the basis of the emotions they associate with their mealtimes and snack times (from now on referred to as mealtimes). Participants (n = 392, mean age 65.8 (years) ± 5.9 (SD)) completed an online survey. The survey consisted of three questionnaires: emotions associated with mealtimes, functionality of mealtimes, and psychographic characteristics (health and taste attitudes, food fussiness, and food neophobia). Consumer segments were identified and characterised based on the emotions that the respondents reported to experience at mealtimes, using a hierarchical cluster analysis. Clusters were described using variables previously not included in the cluster analysis, such as functionality of mealtimes and psychographic characteristics. Four consumer segments were identified: Pleasurable averages, Adventurous arousals, Convivial indulgers, and Indifferent restrictives. These segments differed significantly in their emotional associations with mealtimes both in valence and level of arousal. The present study provides actionable insights for the development of products and communication strategies tailored to the needs of vital community-dwelling older persons.

Effectiveness of flavour nutrient learning and mere exposure as mechanisms to increase toddler's intake and preference for green vegetables.

Children's consumption of vegetables is still below recommendations. Since preference is the most important predictor of children's intake and most children dislike vegetables, new strategies are needed to increase their preferences for vegetables. Flavour nutrient learning (FNL) could be an effective mechanism to change preferences. Forty healthy toddlers were included in a randomized intervention study. During an intervention period of 7weeks, they consumed vegetable soups (endive and spinach) twice per week. Half of the group received a high-energy variant of one soup (e.g. HE spinach) and a low energy variant of the other (LE endive), whereas for the other half the order was reversed (HE endive, LE spinach). Primary outcome measures were preference and ad libitum consumption (with a maximum of 200g) of both vegetable products (LE), measured before, shortly after the intervention period, and 2 and 6months following conditioning to assess longer-term effects. After completion of the intervention period, 28 children (14 girls and 14 boys, age 35months; SD±8.3) met criteria for FNL to occur, and were included in further data analysis. Results showed a significant increase (~58g) in ad libitum intake for both vegetable soups (stable over time), but irrespective of the energy content. This indicates a robust effect of mere exposure on intake, but no FNL. For preference, however, results showed a significant shift in liking for the vegetable soup consistently paired with high energy, supporting FNL.

Tentative evidence for striatal hyperactivity in adolescent cannabis-using boys: a cross-sectional multicenter fMRI study.

Adolescents' risk-taking behavior has been linked to a maturational imbalance between reward ("go") and inhibitory-control ("stop")-related brain circuitry. This may drive adolescent drug-taking, such as cannabis use. In this study, we assessed the non-acute effects of adolescent cannabis use on reward-related brain function. We performed a two-site (United States and Netherlands; pooled data) functional magnetic resonance imaging (fMRI) study with a cross-sectional design. Twenty-one abstinent but frequent cannabis-using boys were compared with 24 non-using peers on reward-related brain function, using a monetary incentive delay task with fMRI. Focus was on anticipatory and response stages of reward and brain areas critically involved in reward processing like the striatum. Performance in users was normal. Region-of-interest analysis indicated striatal hyperactivity during anticipatory stages of reward in users. Intriguingly, this effect was most pronounced during non-rewarding events. Striatal hyperactivity in adolescent cannabis users may signify an overly sensitive motivational brain circuitry. Frequent cannabis use during adolescence may induce diminished ability to disengage the motivational circuit when no reward can be obtained. This could strengthen the search for reinforcements like drugs of abuse, even when facing the negative (non-rewarding) consequences.

Food-Evoked Emotions and Optimal Portion Sizes of Meat and Vegetables for Men and Women across Five Familiar Dutch Meals: An Online Study.

Portion size manipulation is well known to be effective in increasing vegetable intake in adults, whereas less is known about the effects of portion size manipulation on reducing meat intake. This online study investigated the effects of recommended and regularly consumed portion sizes of vegetables and meat in five familiar Dutch meals. Participants evaluated 60 food pictures of five meals and used a 100 mm VAS to measure expected liking, satiety, food-evoked emotions, and the perceived normal portion size. The results show that both regular and recommended portions scored above 55 on the 100 mm VAS on expected liking and satiety. Similarly, both portion sizes scored high (55-70 on the 100 mm VAS) in positive emotions (i.e., happy, relaxed, and satisfied). Regarding the perceived amount of meat, men consistently preferred larger portions of meat than women. However, the optimal portion sizes of vegetables were similar for men and women. Furthermore, the recommended portion sizes led to positive food-evoked emotions, implying that the effective implementation of portion size strategies for increasing vegetable and limiting meat intake requires a careful, holistic approach focusing on the sensory characteristics of food products as well as the emotions evoked by the total food experience.

Effects of Δ9-tetrahydrocannabinol administration on human encoding and recall memory function: a pharmacological FMRI study.

Deficits in memory function are an incapacitating aspect of various psychiatric and neurological disorders. Animal studies have recently provided strong evidence for involvement of the endocannabinoid (eCB) system in memory function. Neuropsychological studies in humans have shown less convincing evidence but suggest that administration of cannabinoid substances affects encoding rather than recall of information. In this study, we examined the effects of perturbation of the eCB system on memory function during both encoding and recall. We performed a pharmacological MRI study with a placebo-controlled, crossover design, investigating the effects of Δ9-tetrahydrocannabinol (THC) inhalation on associative memory-related brain function in 13 healthy volunteers. Performance and brain activation during associative memory were assessed using a pictorial memory task, consisting of separate encoding and recall conditions. Administration of THC caused reductions in activity during encoding in the right insula, the right inferior frontal gyrus, and the left middle occipital gyrus and a network-wide increase in activity during recall, which was most prominent in bilateral cuneus and precuneus. THC administration did not affect task performance, but while during placebo recall activity significantly explained variance in performance, this effect disappeared after THC. These findings suggest eCB involvement in encoding of pictorial information. Increased precuneus activity could reflect impaired recall function, but the absence of THC effects on task performance suggests a compensatory mechanism. These results further emphasize the eCB system as a potential novel target for treatment of memory disorders and a promising target for development of new therapies to reduce memory deficits in humans.

Associations of Regular Marijuana Use by Adolescent Boys With Verbal Memory and Perseveration.

Many American and Dutch adolescents use marijuana regularly. There is concern that such use may impair cognitive function more in adolescents than adults. We examined effects of regular marijuana use on long-term memory and perseveration among American and Dutch adolescents. We administered Buschke's Selective Reminding Test (BSRT) to assess long-term memory and the Wisconsin Card Sorting Test (WCST) to assess perseveration in male teenagers. Usable test data were obtained for 12 American marijuana users, 13 American controls, 9 Dutch marijuana users, and 12 Dutch controls. In BSRT, users showed lower overall long-term storage than controls (adjusted means ± SE's for numbers of words per trial of 9.4 ± 0.2, 13.4 ± 0.3, 11.7 ± 0.2, and 12.4 ± 0.2 for American users, Dutch users, American controls, and Dutch controls, respectively). Marijuana was associated with memory effects only in American, not Dutch, users. Bivariate Pearson correlations for American and Dutch users combined showed associations of lower total recall with more uses in the previous year and lifetime (r = -0.61 and r = -0.53, respectively); and more perseverative errors with more uses in the previous year (r = 0.55). Some findings were consistent with the possibility that regular adolescent marijuana use causes deficits in cognition, especially memory. However, a causal interpretation cannot be inferred from our findings and is challenging to reconcile with the observation of memory deficits only in American users. Our study was novel in examining the influence of nationality on marijuana's cognitive effects. More studies of this topic should compare effects across nationalities or cultures.

Evidence for involvement of the insula in the psychotropic effects of THC in humans: a double-blind, randomized pharmacological MRI study.

The main reason for recreational use of cannabis is the 'high', the primary psychotropic effect of Δ9-tetrahydrocannabinol (THC). This psychoactive compound of cannabis induces a range of subjective, physical and mental reactions. The effect on heart rate is pronounced and complicates bloodflow-based neuroimaging of psychotropic effects of THC. In this study we investigated the effects of THC on baseline brain perfusion and activity in association with the induction of 'feeling high'. Twenty-three subjects participated in a pharmacological MRI study, where we applied arterial spin labelling (ASL) to measure perfusion, and resting-state functional MRI to assess blood oxygen level-dependent signal fluctuation as a measure of baseline brain activity. Feeling high was assessed with a visual analogue scale and was compared to the imaging measures. THC increased perfusion in the anterior cingulate cortex, superior frontal cortex, and insula, and reduced perfusion in the post-central and occipital gyrus. Baseline brain activity was altered, indicated by increased amplitude of fluctuations in resting-state functional MRI signal after THC administration in the insula, substantia nigra and cerebellum. Perfusion changes in frontal cortex were negatively correlated with ratings of feeling high, suggesting an interaction between cognitive control and subjective effects of THC. In conclusion, an acute THC challenge altered baseline brain perfusion and activity, especially in frontal brain areas involved in cognitive and emotional processes, and the insula, associated with interoceptive awareness. These changes may represent the THC-induced neurophysiological correlates of feeling high. The alterations in baseline brain perfusion and activity also have relevance for studies on task-related effects of THC on brain function.