Summary: Researchers report high fat diets in teens is associated with poor stress coping skills later in life.
Source: Loma Linda University.
A new study published in the journal Brain, Behavior, and Immunity shows that adolescent rats who consume a diet high in saturated fats have a harder time coping with stress as adults. Moreover, researchers from Loma Linda University in California found that the areas of the brain that handle the fear/stress response were altered to the point that subjects began exhibiting behaviors that mirror post-traumatic stress disorder (PTSD).
“The teen years are a very critical time for brain maturation, including how well (or not) we’ll cope with stress as adults,” said Dr. Johnny Figueroa, Assistant Professor, Division of Physiology, Department of Basic Sciences and Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine. “The findings of our research support that the lifestyle decisions made during adolescence – even those as simple as your diet – can make a big difference in our ability to overcome every day challenges.”
The study, “Exposure to an obesogenic diet during adolescence leads to abnormal maturation of neural and behavioral substrates underpinning fear and anxiety,” investigated the impact of an obesogenic Western-like high-saturated fat diet on the development of brain areas involved in responding to fear and stress. Study findings demonstrate that the consumption of an obesogenic diet during adolescence has a profound effect on phasic and sustained components of fear in the adult rat. Notably, the rats that consumed the high-saturated fat diet exhibited more anxiety, problems with associative and non-associative learning processes and an impaired fear-startle response.
Startle reflexes, which are studied in humans and lab animals, have a prominent role in anxiety and PTSD research. In this study, consumption of an obesogenic diet during adolescence reduced the extinction of fear memories – a major impairment observed in people suffering from PTSD. In addition to not properly learning fear associations, the rats on the high-saturated fat diet incorrectly assessed the level of threat. This suggests that obesity and associated metabolic alterations may predispose individuals to PTSD-related psychopathology.
Researchers reported that the animals in the high-saturated fat diet group exhibited alterations in the structure of brain regions associated with PTSD, including the amygdala and the prefrontal cortex. Notably, the group found that the left-brain hemisphere seems to be more vulnerable to the effects of high-saturated fat diet consumption and obesity-related metabolic alterations. Understanding the neural networks that predispose obese adolescents to developing anxiety and stress-related disorders may help target metabolic measures to alleviate the burden of mental illness in this growing population.
Figueroa said the study leaves other questions open for further investigation, such as replicability in human subjects and if the alterations seen in the brain structures are permanent or whether the effects can be reversed. Study limitations include lack of clarity on how the high-saturated fat diet impacts the adult brain, and whether the effects of the obesogenic diet on the fear response are related to deficits in fear memory consolidation, retrieval and expression.
Source: Kimberly Wise – Loma Linda University
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Original Research: Abstract for “Exposure to an obesogenic diet during adolescence leads to abnormal maturation of neural and behavioral substrates underpinning fear and anxiety” by Julio David Vega-Torres, Elizabeth Haddad, Jeong Bin Lee, Priya Kalyan-Masih, Wanda I. Maldonado George, Leonardo López Pérez, Darla M. Piñero Vázquez, Yarí aArroyo Torres, José M. Santiago Santana, Andre Obenaus, and Johnny D.Figueroa in
Brain, Behavior and Immunity. Published May 2018
Exposure to an obesogenic diet during adolescence leads to abnormal maturation of neural and behavioral substrates underpinning fear and anxiety
Post-traumatic stress disorder (PTSD) and obesity are highly prevalent in adolescents. Emerging findings from our laboratory and others are consistent with the novel hypothesis that obese individuals may be predisposed to developing PTSD. Given that aberrant fear responses are pivotal in the pathogenesis of PTSD, the objective of this study was to determine the impact of an obesogenic Western-like high-fat diet (WD) on neural substrates associated with fear.
Adolescent Lewis rats (n = 72) were fed with either the experimental WD (41.4% kcal from fat) or the control diet. The fear-potentiated startle paradigm was used to determine sustained and phasic fear responses. Diffusion tensor imaging metrics and T2 relaxation times were used to determine the structural integrity of the fear circuitry including the medial prefrontal cortex (mPFC) and the basolateral complex of the amygdala (BLA).
The rats that consumed the WD exhibited attenuated fear learning and fear extinction. These behavioral impairments were associated with oversaturation of the fear circuitry and astrogliosis. The BLA T2 relaxation times were significantly decreased in the WD rats relative to the controls. We found elevated fractional anisotropy in the mPFC of the rats that consumed the WD. We show that consumption of a WD may lead to long-lasting damage to components of the fear circuitry.
Our findings demonstrate that consumption of an obesogenic diet during adolescence has a profound impact in the maturation of the fear neurocircuitry. The implications of this research are significant as they identify potential biomarkers of risk for psychopathology in the growing obese population.