Heather M Francis

Macquarie University, Sydney, New South Wales, Australia

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Publications (6)18.06 Total impact

  • Mairead Brannigan · Richard J Stevenson · Heather Francis
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    ABSTRACT: Less sensitive interoception for hunger and fullness has been observed in people who consume a diet rich in saturated fat and added sugar. In this study we examined whether healthy young people who routinely consume such diets, also demonstrate less sensitive thirst interoception. Participants, varying primarily in diet, were made thirsty by consuming salted chips and later provided with ad libitum access to water, with thirst ratings obtained throughout. A self-report measure of interoceptive awareness was also included plus measures to determine eating habits, memory and executive function. A diet reported as richer in saturated fat and added sugar (an HFS diet) was associated both with less sensitive thirst interoception and with greater attention to somatic signs. Evidence of poorer hippocampal-sensitive learning and memory was also detected. Poorer sensitivity to interoceptive cues appears to be a reliable correlate of an HFS diet and its causal origins are discussed. Copyright © 2014. Published by Elsevier Inc.
    No preview · Article · Nov 2014 · Physiology & Behavior
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    ABSTRACT: The typical Western diet, rich in saturated fat and refined sugar (HFS), has been shown to increase cognitive decline with aging and Alzheimer's disease, and to affect cognitive functions that are dependent on the hippocampus, including memory processes and reversal learning. To investigate neurophysiological changes underlying these impairments, we employed a proteomic approach to identify differentially expressed proteins in the rat dorsal and ventral hippocampus following maintenance on an HFS diet. Rats maintained on the HFS diet for 8 weeks were impaired on a novel object recognition task that assesses memory and on a Morris Water Maze task assessing reversal learning. Quantitative label-free shotgun proteomic analysis was conducted on biological triplicates for each group. For the dorsal hippocampus, 59 proteins were upregulated and 36 downregulated in the HFS group compared to controls. Pathway analysis revealed changes to proteins involved in molecular transport and cellular and molecular signalling, and changes to signalling pathways including calcium signalling, citrate cycle and oxidative phosphorylation. For the ventral hippocampus, 25 proteins were upregulated and 27 downregulated in HFS fed rats. Differentially expressed proteins were involved in cell-to-cell signalling and interaction, and cellular and molecular function. Changes to signalling pathways included protein ubiquitination, ubiquinone biosynthesis, oxidative phosphorylation and mitochondrial dysfunction. This is the first shotgun proteomics study to examine protein changes in the hippocampus following long-term consumption of a HFS diet, identifying changes to a large number of proteins including those involved in synaptic plasticity and energy metabolism This article is protected by copyright. All rights reserved.
    Full-text · Article · Aug 2013 · Proteomics
  • Heather Francis · Richard Stevenson
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    ABSTRACT: Animal work over the last three decades has generated a convincing body of evidence that a Western diet - one high in saturated fat and refined carbohydrates (HFS diet) - can damage various brain systems. In this review we examine whether there is evidence for this in humans, using converging lines of evidence from neuropsychological, epidemiological and neuroimaging data. Using the animal research as the organizing principal, we examined evidence for dietary induced impairments in frontal, limbic and hippocampal systems, and with their associated functions in learning, memory, cognition and hedonics. Evidence for the role of HFS diet in attention deficit disorder and in neurodegenerative conditions was also examined. While human research data is still at an early stage, there is evidence of an association between HFS diet and impaired cognitive function. Based upon the animal data, and a growing understanding of how HFS diets can disrupt brain function, we further suggest that there is a causal link running from HFS diet to impaired brain function in humans, and that HFS diets also contribute to the development of neurodegenerative conditions.
    No preview · Article · Jan 2013 · Appetite
  • H Francis · R Stevenson
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    ABSTRACT: The present study aimed to conduct a preliminary investigation of the validity and reliability of a short dietary questionnaire designed to assess dietary intake of saturated fat and free sugars. Forty students at Macquarie University, aged 17–46 years, completed the Dietary Fat and free Sugar – Short Questionnaire (DFS), a full-length food frequency questionnaire (C-FFQ) and a 4-day diet diary (DD). After a mean (SD) follow-up time of 158 (10) days, 29 participants completed a second administration of the DFS. Correlation coefficients comparing DFS scores with the percentage energy from saturated fat and free sugar assessed by the C-FFQ and DD ranged from 0.35 to 0.71. The intraclass correlation (0.83) was high, indicating good reliability. These results suggest that the DFS is a valid and reliable measure of saturated fat and free sugar intake. Because it is quick to administer and score, in the public domain, and easy to interpret, it maybe useful as a screener, simple self-check tool or for large-scale epidemiological studies.
    No preview · Article · Nov 2012 · Journal of Human Nutrition and Dietetics
  • Heather M Francis · Richard J Stevenson
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    ABSTRACT: Regulation of energy intake depends in part on both memory for prior food intake and internal signals of hunger and satiety. These functions are both mediated by the hippocampus, a brain structure that animal studies have shown to be impaired after maintenance on high fat and refined sugar (HFS) diets. Study 1, using a cross-sectional design, revealed that self-reported HFS diet was associated with poorer performance on hippocampal sensitive memory tasks but not other neuropsychological control measures. Study 2 replicated this finding in two groups selected to differ in HFS intake, additionally showing that this effect is specific to hippocampal functioning and does not extend to measures of prefrontal cortex function. Furthermore, in a laboratory-based test of food intake, the HFS rich diet groups were less accurate in recalling what they had previously eaten and evidenced reduced sensitivity to internal signals of hunger and satiety, relative to a group consuming less HFS rich diets. Together, these findings reveal an association between HFS consumption and poorer hippocampal function in human participants, consistent with findings from animal-based studies. Moreover, our results suggest that this may be related to impaired regulation of energy intake via less accurate tracking of prior food intake and reduced sensitivity to hunger and satiety signals.
    No preview · Article · Dec 2011 · Behavioral Neuroscience
  • H M Francis · N J Kraushaar · L R Hunt · J L Cornish
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    ABSTRACT: 3,4-Methylenedioxymethamphetamine (MDMA) abuse is a substantial problem in young adults. Due to a high focus on body image in this population, two main factors that may encourage MDMA use are the appetite suppressant and locomotor stimulant effects of this drug. The nucleus accumbens (NAc) is a brain region associated with the regulation of motivated and locomotor behaviours, and recent evidence suggests that NAc 5-HT4 receptors are likely to be involved in the appetite suppressant effect of MDMA. It has not yet been shown whether 5-HT4 receptors of the NAc are involved in the locomotor stimulant effects of MDMA, which may also contribute to a reduction in food intake. This study aimed to investigate the effect of local antagonism of serotonin 5-HT4 receptors in the NAc in the appetite suppressant and locomotor stimulant effects of MDMA. Male hooded Wistar rats underwent surgery for the implantation of bilateral NAc microinjection cannulae under isofluorane anesthesia. Following 5-7 days of recovery, the rats received bilateral microinjections of the 5-HT4 antagonist RS39604 into the NAc immediately prior to either saline or MDMA administration. Food intake, water intake, body weight and locomotor activity were measured. RS39604 significantly increased food intake and increased weight loss in MDMA-treated but not saline-treated rats. Measures of MDMA-induced water intake or locomotor activity were not altered by antagonist administration. These results demonstrate that 5-HT4 receptors in the NAc specifically regulate the appetite suppressant effects of MDMA but not MDMA-induced water intake or locomotor activity.
    No preview · Article · Feb 2011 · Psychopharmacology