Food Addiction
Ruddock and Hardman (2017) found that self-perceived food addicts rated food as more rewarding and ate significantly more chocolate
A controversial concept
Why do we care? There may be important policy and treatment implications (fat/sugar tax, control marketing, screening for addiction in weight loss programmes)
Similar effects of food and drugs on brain reward symptoms
Common brain reward systems: Food and drugs activate the same brain circuits, increased dopamine signalling in the NAcc (Hajnal et al, 2004; Di Chiara &Imperator, 1988; Tang et al, 2012)
Incentive-sensitisation hypothesis: High intake of food may sensitise the dopamine system in some way, overtime. So, dopamine response to food sensitises there is increased wanting to foods and this excessive wanting may underpin a feeling of addiction to foods (Robinsonson and Berridge, 1993).
Reward deficiency hypothesis: Overtime there may be a blunting of the Dopamine response to food, making the ability to experience reward reduced, and this leads to higher consumption. (Kenny et al. 2003; Johnson and Kenny, 2010)
No direct evidence from research in humans, and existing evidence of food addiction associated with alteration of dopamine circuits have inconsistent results.
Animal models: Sugar addiction model (Colantuoni et al., 2001); animals given sweet glucose solution with full access or intermittent access. Overtime intermittent access to glucose causes binge like behaviour.
In these animals, cross-sensitisation studies show that their dopamine system is sensitised with animals having intermittent glucose access followed by an injection of amphetamine, measuring locomotor responses intermittent animals showed a greater response to amphetamine (Avena and Hoebel, 2003).
Long term exposure to cafeteria diet (Johnson and Kenny, 2010) Rats get access to high fat/sugar foods in as much quantity as they want, measuring the willingness of animals to do work to get brain stimulation, if they press the lever more they are requiring more reward to maintain response. Extended access to cafeteria diet, the animals are require greater stimulation to maintain behaviour, suggesting they are experiencing a reduction in their sensitivity to reward
Clinical addiction
Yale Food Addiction Scale: trying to apply the DSM-5 criteria for substance use disorder: items endorsed by obesity and addiction experts (impaired control, social impairment, risky use, pharmacological criteria; tolerance/withdrawal)
Meule & Gearhardt (2019) Evidence that some people report problems with eating that resemble addiction. Prevalence of food addiction seems to be greater in those who are obese or who have eating disorders
Lots of research recently looking at if its a valid concept. the measurements, links to obesity and animal models
Studies injecting sucrose and amphetamine show similar dopamine patterns. Increased brain activity in reward related areas when exposed to food and drug-related pictures
These theories are not necessarily mutually exclusive, maybe initially individuals are more sensitised to reward, promoting addictive behaviour, and as a result of the addictive behaviour you see desensitisation occurring due to overconsumption, maintaining the behaviour (Garcia-Garcia et al. 2020)
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Risk factor: those with hyper-activity of reward system are more likely to develop food addiction leading to larger consumption, as a result of overconsumption an individuals goes through incentive sensitisation or reward deficiency , which maintains food addiction.
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Issues: Is it certain foods that are addictive or a person develops behavioural addiction to eating?
Is food addiction a valid and helpful concept? Is it different from eating disorders, like binge eating?
NOT A DSM-V DISORDER CURRENTLY- VERY NEW
Some people report problems with eating that resemble features of addiction
Animal models shows that foods may act like drugs on the brain. Is this relevant to humans? different diets to humans and the circumstances are particular to kickstart overconsumption.
Patterns of consumptions of palatable foods that alter brain reward systems
Labelling a food 'addictive' implies it contains ingredients with the capacity to make individuals addicted- just because something engages the reward system doesn't mean individuals will become addicted- its not the substance that's an issue but the pattern of behaviour. So is it eating addiction VS food addiction.
Food addiction captures some aspects of BED, there is some overlap but not complete overlap. Maybe it is a subtype (Davis, 2013)
Might be helpful for treatment and policies.