Wednesday, January 21, 2015

Current Research on Food Addiction

I actually wrote this paper for my Biopsychology class, but I thought that some of you might find it interesting/useful.  So, with that said, here it is.  Note that this isn't my usual snazzy writing style, so if you need a good nap, this might do the trick.

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Introduction
            There are many factors that contribute to the tremendous obesity problem in the United States and other Western countries.  One of these, food addiction, is a relatively new addition to the scientific world.  Food addiction was first introduced into scientific literature in the mid-1950’s  (Randolph, 1956).  While food addiction was only touched upon in literature about 9 times between 1956 and 2007, 2008 to the present time has seen a huge influx in studies about food addiction, with over 65 studies published between 2008 and 2012 (Salamone & Correa, 2013).  In this paper, I will discuss current findings about food addiction as well as developing research on the subject.  I will note ethical considerations surrounding the subject of food addiction, including those regarding gender and diversity.  I will summarize with my thoughts on future directions that research in food psychology might take, and how this research might be used to improve the health and well-being of our society.
Current Findings
            In 2009, Ashley Gearhardt developed the Yale Food Addiction to diagnose food addictive behavior.  She based her scale on the Diagnostic and Statistical Manual of Mental Disorders (APA, 2000; Gearhardt, et al., 2009).  The scale has been validated by a number of different sources as a reliable tool that demonstrates food-related behaviors that are similar to drug addictive behaviors (Brunault, et al., 2014; Pursey, et al., 2014; Gearhardt, Corbin, & Brownell, 2009). 
            Avena, Rada, and Hoebel (2008) argue that the same neural mechanisms that instill the drive to gather food are those that foster drug addiction.  In an animal study, sugar consumption has been found to release opioids, acetylcholine, and dopamine in the brain, which would indicate an addictive response (Avena, Rada, & Hoebel, 2008).  The sugar addiction pattern seemed to follow a pattern of binging, withdrawal, craving, and sensitization, as with an addictive substance.  While the symptoms were milder than those for drugs, they caused significant patterns of uncontrolled overeating of sugary substances and a mild dependency on these foods. 
            Liu, von Deneen, Kobeissy, & Gold (2010) note that alterations in the function and structure of the brain occur as a result of habitual abnormal eating habits.  For instance, when obese subjects were given appealing foods, the portions of the brain linked to the release of dopamine were activated.  The authors also note that both food and drugs utilize the mesolimbic reward system of the brain in order to create a pattern of re-use and craving.  This pattern will cause the food addict to choose the food over the consequences related to eating that food. 
            Another study notes a similar effect of salty foods (Cocores & Gold, 2009).  Sodium tends to be sought out only in circumstances in which the body is deficient in it.  However, the authors found that pregnant rats fed a processed and salty foods diet have offspring who crave these foods and tend to be obese.  There appears to be a relationship between how much salt an infant is fed before 6 months of age and preference of that child for salty foods.  The authors found that salty food intake also activates the dopamine and opioid centers of the brain to create an addictive response, and that non-deficiency-related cravings for salty foods are due to withdrawal of dopamine and opioid stimulation.
            Another study demonstrated an addictive-like quality of a high-fat diet in rats (Puhl, et al., 2008).  The rats in the study that had a very high-fat diet were more likely to self-administer cocaine and display more severe addictive behaviors. 
Current New Research
Food addiction has recently gotten validation in the scientific community.  Binge eating is a relatively recent addition to the addictions portion of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) (APA, 2013).  The APA notes that binge eating is a different and rarer condition from overeating, and that it is linked to significant psychological dysfunction.
Both human and animal studies have shown great similarities between physiological responses between drug addiction and bulimia nervosa—the dopamine response, glutamatergic signaling, opiod system, and neural activity in the cortex all react similarly between drug addicts and bulemics (Hadad & Knackstedt, 2014).  In a study of obese individuals with binge eating disorder, those who scored higher on the Yale Food Addiction Scale had significantly more severe binge eating symptoms and problems associated with overeating (Gearhardt, et al., 2013).  Those who scored high on the food addiction scale also tended to have a younger age of overweight onset but not of dieting onset.   A subgroup of those who had symptoms of food addiction but not a formal diagnosis also showed younger patterns of dieting behaviors.  Those diagnosed with food addiction were related to lower self-esteem measures and significantly higher concern with weight and shape, but did not reflect attempts to curb the eating problem.  Diagnosed food addicts also seemed to have higher measures of impulsiveness, reactivity, and cravings for specific foods.
            Food addiction has been linked to with sexual and physical abuse in childhood (Mason, et al, 2013).  This study utilized a modified version of the Yale Food Addiction Scale to diagnose the addiction, and found that women with a food addiction diagnosis were 6 units higher in body mass index (BMI) than those with no diagnosis.  Of the women diagnosed with food addiction, almost 2/3 had a BMI of over 30 kg/m2, whereas approximately ¼ of those without food addiction met this criterion.  Women who had a childhood history of abuse, either physical, sexual, or both, were significantly more likely to have a food addiction diagnosis, and this number increased proportionately to the number of times they had been abused, as well as with those who had been both physically and sexually abused.
            Despite this evidence, the concept of food addiction is still surrounded by controversy and has not been accepted by all scientists.  Ziauddeen, Hisham, Farooqi, and Fletcher, for instance, note that brain imaging studies have not demonstrated reliable responses by the brain’s reward systems, and that most of the studies done regarding food addiction have been grossly inconsistent in their results.  Smith and Robbins (2013) note discrepancies between the way the brain reacts towards drugs and towards food. 
            Puhl, et. al. (2011) point out that with drug addiction, there is an inherent “wanting” of the drug without necessarily having a “liking” for the drug.  There is also a “wanting” for highly palatable foods in binge eating, but that “wanting” is also paired with a significant “liking” of the food.  Most binge eaters do not crave foods they do not enjoy the taste of.  This, the authors argue, sets binge eating apart from drug addiction and is an argument against the existence of food addiction.
            Several studies make note of the fact that food, unlike drugs, is necessary for survival, which would automatically set it apart from an addictive substance (Krashes & Kravitz, 2014).  It has also been demonstrated that a diagnosis of food addiction does not necessarily precipitate obesity (Salamone & Correa, 2013).  Krashes and Kravitz (2014) point out that changes in the mechanisms that control appetite may be more at play than druglike addictive responses.  When put on a diet, the subjects will find themselves deficient in calories, attempting to fight their body’s reinforcement strategies, and under emotional stress.  This generally will lead to more food-seeking behaviors.  The authors do concede that deficits in the prefrontal cortex, which are related to drug addiction, may also be linked to lack of control over food consumption.  They conclude that the argument for food addiction is compelling, although there remain significant differences between food and drug addiction. 
Salamone and Correa (2013) argue that since food is a necessity to survival, dependence and withdrawal symptoms related to its consumption are meaningless.  The authors also take issue with the fact that the classification of the dopamine system as a reward system is, in and of itself, a controversial matter.  The classification of dopamine as a hedonistic mediator has not been proven—some studies have shown that manipulations of dopamine did not affect mood or motivation (Salamone & Correa, 2013).  The authors note that dopamine plays a significant role in appetite and motivation to eat, which would explain its activation in food consumption.  Furthermore, the activation of dopamine varies based on the conditions, the food supplied, whether or not the food was novel, and the dopamine terminal region of the brain.
Ethical Considerations
            While there are few current ethical conflicts in the study of food addiction, it is important to consider that this is a problem most likely to plague Westernized nations and individuals with access to large quantities of food.  Therefore, it has significant socioeconomic considerations.  While it is a common assumption that fast food, sugary drink, and other junk food consumption combined with low fruit and vegetable consumption is more prevalent among lower socioeconomic classes, it has been demonstrated that these problems span the entire economic spectrum of the United States (Sturm & An, 2014).  Likewise, an increase in body mass index has affected all socioeconomic classes relatively equally in recent years.  Even when prices for healthier foods are lower, people appear less likely to be motivated to purchase those foods without some sort of intervention. 
            There is some concern about a stigma associated with food addiction, as there would be with any emotional or psychological disorder.  As weight discrimination is already a significant problem in Westernized society (Suh, Puhl, Liu, & Fleming Milici, 2014), coupling this with an additional perceived cognitive disorder could have traumatic emotional repercussions on those who suffer from both obesity and a food addict label.  Alternatively, the label might help relieve some of the stigma associated with obesity—if the obese individual is diagnosed with a condition proving that there is a medical basis for the overeating conditions, there might be more compassion towards that person.  There is also a third possibility, in which the stigma of being an addict carries its own weight regardless of obesity.  In a study designed to determine how much of a stigma food addiction would carry, DePierre, Puhl, and Luedicke (2013) explored all of these options.  In the fist portion of their study, the authors discovered that while people would have far more compassion for someone with a disability, they would also generally choose to distance themselves from that person.  The authors also explored the effects of gender and race on the food addiction stigma.  They found that women gave less of a stigma to obesity, food addiction, and other labels, but more towards smokers and cocaine addicts.  African Americans were more tolerant towards addicted individuals than were Caucasians, and obese individuals were more sympathetic towards obese food addicts and placed less responsibility on them than did thinner individuals.  In general, the authors discovered that food addiction carried less of a stigma than did other addictions such as cocaine and nicotine, but carried a similar stigma to obesity.  Furthermore, food addiction and obesity carried more of a negative connotation than did other non-addictive health conditions.  The second part of the study had very similar results.  An interesting aspect of this portion of the study was that when a hypothetical male subject was assessed by the subjects, obesity did not seem to come into play in their opinion of him.  It would be interesting to see the results had the subject to be assessed been a woman, or had the race of the subject varied.
            One study did utilize a hypothetical female subject in their vignette (Lee, et al., 2014).  However, their subject pool was predominantly female, which might skew results.  The authors found, once again, that obese and food addicted participants were more likely to assign responsibility for another person’s obesity on biological causes.  Overweight participants tended to blame environmental causes, while normal weight participants blamed personal responsibility.  Interestingly, obese subjects were less likely to assign overeating as a cause of obesity than were overweight subjects. 
            Few studies have examined ethnic, socioeconomic, or gender differences in food addiction.  One small study showed that African-Americans were more prone to food addiction than were Caucasians (Thompson & Romeo, 2014).  Females of both races reported dissatisfaction with their bodies more than males did.  Females of both races also reported more emotional reasoning such as anxiety and depression behind their tendencies to overeat than did men. 
Conclusion
            While science is becoming more accepting of the idea of food addiction, there has yet to be reliable and conclusive human-based evidence proving that food addiction is, in fact, a medical condition comparable to drug addiction.  While most studies have been dedicated to examining neurological and self-determined aspects that might define food addiction, there appears to be a significant paucity of research concerning gender, ethnic, and socioeconomic factors surrounding the food addiction diagnosis.  If food addiction is, indeed, a medical condition, considering the significant emotional factors that are entwined with overeating, there is likely no one-size-fits-all approach to treating this disorder.  Just as drug addiction and obesity treatment generally require multi-pronged approaches, rehabilitation from food addiction would likely require the same, and would need to be highly individualized.  Research needs to be done on how treatment of co-existing conditions such as depression and anxiety might affect a diagnosis of food addiction—if, for instance, the depression or anxiety is successfully treated, would the food addiction disappear, or would it need separate treatment?  Furthermore, if the stigma of food addiction creates social isolation (DePierre, Puhl, and Luedicke, 2013), research on what sort of support measures can be instilled to help create more accepting communities and social outlets for those afflicted with the disorder, and whether these options might help relieve the need to overeat. 
            Food addiction is still a very new and poorly understood subject.  A standard for its evaluation and a consensus on its existence need to be determined before treatment options can be explored.  In the meantime, in light of current research, it would appear that increasing the appeal of healthier food purchases might be of particular importance (Sturm & An, 2014).  Should junk foods become less popular (or, at least, less available), fruit and vegetables become more desirable, and physical activity be encouraged in schools, businesses, and communities in general, the obesity epidemic might just take care of itself.



References
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Thompson, S., & Romeo, S. (2014). Gender and racial differences in food addiction symptoms, body satisfaction and overeating influences. Journal Of The Academy Of Nutrition & Dietetics, 114(9), A36.

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