1

The Addiction Model is Appropriate for Use with Food

Nicole M. Avena, Ph.D.New York Obesity Research Center

Columbia University

Outline of the Presentation

The problem of obesity

A brief outline of factors thought to contribute to the rise inobesity

Background on food-reward and select associated brainsystems

Defining an addiction

Assessment of “food addiction” in laboratory animal models

Points for further discussion

Obesity in the US

In 2012, ~69% of adults inthe U.S. were overweight,of which ~35% were obese.

Being obese or overweightis associated with multiplecomorbid health concerns(e.g., heart disease,diabetes).

Increased body weight canalso have psychological,economical, and socialconsequences.

The cost of bothoverweight and obesity inthe US was estimated to be$113.9 billion in 2008, 5-10% of healthcare spending(Tsai et al., 2011).

Why are so many people overweight or obese?

Nicole Avena

2

Portion Size and Portion Creep

Food Acquisition Is Easier Than It Used To Be

Obesity is an endpoint, with multiple contributing factors

Obesity

Sedentary lifestyle

Genetic vulnerability

Food accessibility

Social norms

regarding food

Stress and endocrine

factors

Increases in portion sizes

Genetic disorders (Prader-

Willisyndrome)

Food Reward(addiction?)

What is a food?

Nicole Avena

3

Hunger- vs. Hedonically-driven Eating

Nicole Avena

4

What happens in select parts of the brain when we eat?

Drugs that are abused acton brain systems thatreinforce naturalbehaviors (e.g., sex,feeding).

There are overlaps in thebrain regions activatedby palatable foods anddrugs of abuse.

Could some people be “addicted” to eating highly-palatable foods rich in sweets and fats in ways that resemble drug addiction?

Could such out-of-control eating result in increased body weight and obesity in some individuals?

What is an addiction?

Nicole Avena

5

How Do We Define Addiction?

The DSM-V describes a substance use disorder as…

“a cluster of cognitive, behavioral, and physiological symptoms indicating that the individual continues using the substance despite significant substance-related problems.”

DSM-V Criteria for Substance Use DisordersCriterion A: Impaired Control

• Binge - Taking the substance in largeramounts or over a longer period thanoriginally intended

• Desire to limit or quit - Persistentdesire to cut down or regulatesubstance use and may reportmultiple unsuccessful efforts todecrease or discontinue use

• Time - A great deal of time is spentobtaining, using, or recovering fromthe effects of the substance

• Craving - an intense desire or urge forthe drug

Criterion B: Social Impairment

• Recurrent substance use may result ina failure to fulfill major roleobligations at work, school, or home

• Substance use is continued despitehaving recurrent social orinterpersonal problems caused orexacerbated by the effects of thesubstance

• Important social, occupational, orrecreational activities may begiven up or reduced

Criterion C: Risky Use

• Recurrent substance use in situationsin which it is physically hazardous

• The individual may continue substanceuse despite knowledge of having apersistent or recurrent physical orpsychological problem that is likely tohave been caused or exacerbated bythe substance

Criterion D: Pharmacological

• Tolerance - requiring an increaseddose of the substance to achieve thedesired effect or a markedly reducedeffect with the usual dose

• Withdrawal - occurs when blood ortissue concentrations of a substancedecline in an individual who hadmaintained prolonged heavy use ofthe substance

DSM-V Criteria for Substance Use Disorders

Note: The DSM-V indicates that “for certain classes [of drugs] some symptoms are less salient, and in a few instances not all symptoms apply (e.g., withdrawal symptoms are not specified for inhalant use disorder).

The Utility of Animal Models

Allow us to study physical andpsychological disorders, andpossible treatments, in waysthat would otherwise beunfeasible

Allow us to isolate thebiological mechanismsassociated with a disorderwithout the influence ofpotentially confoundingvariables such as social andcultural influences

Note: animal models provide a method of investigating specific aspects or symptoms, that characterize a disorder.

Nicole Avena

6

Added Sugar Consumption in the United States

Added sugar, as measured here, includes: white, brown and raw sugar, syrup, honey, and molasses that were eaten separately or used as ingredients in processed or prepared foods such as breads, cakes, soft drinks, jams, and ice cream.

The National Cancer Institute (2010)

Bingeing/Tolerance

Daily Intermittent Sucrose and Chow Daily Ad libitum

Sucrose and ChowSucrose Twice

Rada, Avena, and Hoebel (2005)

Alterations in Brain Dopamine Levels

All ratsBinge group

Rada, Avena and Hoebel (2005)

• Increases in dopamine (DA) release wane with repeated exposure tochow; however, theseincreases continue in response to sugar.

• This effect is onlyseen in sugar-bingeing rats, not control rats.

• This effect is alsoseen in response to fat (Liang, Hajnal, &Norgren, 2006).

• Rats are notoverweight.

Nicole Avena

7

Colantuoni et al. (2001); Avena, Bocarsly, et al. (2008)

Withdrawal

• Sugar bingeing rats show signs of anxiety when given an opioid antagonist(naloxone), or when fasted from all food for 36 h.

• Opioid systems are perturbed by overeating, as revealed by increased mu-opioid receptor binding in these animals prior to withdrawal.

Avena, Bocarsly, et al. (2008)

DEPRIVATION

Neural correlates of withdrawal

Withdrawal from sugar is concurrent with decreases in dopamine and increases in acetylcholine levels in the nucleus accumbens, similar to the pattern seen during drug withdrawal.

Rats prone to overeat aremore likely to cross a shockgrid to access palatable food(Oswald, Murdaugh, King &Boggiano, 2011). A recentstudy also found that rats leverpressing for palatable foodwere more resistant to theeffects of punishment (mildfoot shock) than rats leverpressing for methamphetamine(Krasnova et al., 2014).

Rats that overeat sugar dailyshow an increase in intakefollowing a period ofabstinence (Avena et al, 2005),and will work harder to accesssugar-associated cues (Grimmet al., 2005).

Craving

-20-15-10

-505

1015202530

% C

HA

NG

E FR

OM

BA

SELI

NE

** 12-h Daily Sugar

30-min Daily Sugar

0

50

100

150

200

250

300

350

400 Daily IntermittentSucrose and Chow

Daily IntermittentChow

Daily Ad libitumSucrose and Chow

Daily Ad libitumChow

Amph Test (0.5 mg/kg)Day 29

Day 21Day 1Lo

com

otor

Act

ivity

(% o

f Day

0 b

eam

bre

aks)

Cross-sensitization to drugs of abuse**

Avena and Hoebel (2003); Avena et al. (2004)

• Sugar-bingeing rats arehyperactive inresponse to a low doseof amphetamine.

• Sugar-bingeing ratsconsume more alcohol.

Nicole Avena

8

When we have variety…we tend to eat more.

A number of studies haverevealed that when rats andhumans have a variety of foodsavailable to them, they tend toeat significantly more.

One possible reason for this is“sensory specific satiety.”

Geiger et al. (2009)

• Rats with access to acafeteria-style diet arehyper-responsive toamphetamine in terms ofdopamine release.

• However, they do notrespond to a lab chowmeal. These rats need“junk food” to releaseaccumbens dopamine.

Is the construct of food addiction “distracting”?

“The danger of adopting a food addiction model is that it diverts attention from the main causes of overeating and obesity” (Rogers, 2013)

“…obesity is better viewed as due to a 'toxic' environment” (Rogers, 1999)

Supporting the possible role of food addiction in perpetuating obesity does not preclude the legitimacy of other factors. Rather, food addiction models in the laboratory affirm the importance of the food environment in promoting food addiction.

Nicole Avena

9

Food addiction may be fitting for individuals with binge eating disorder, but is it helpful for understanding obesity?

“Experts mostly agree that (drug) addiction refers to ‘the extreme or psychopathological state where control over drug use is lost’ (Altman et al, 1996). Such extreme loss of control does perhaps characterize binge eating…However, while binge eating may be thought by some to be an example of food addiction and people with binge eating disorder being more likely than non-binge eaters to be obese, most obese people do not have binge eating disorder. More mundanely, extreme loss of control does not describe at all well the repeated failure to resist energy-rich foods and large portions that gradually contributes to weight gain. This is probably the more typical pathway to obesity.” (Rogers, 2013)

The “loss of control” does not have to be “extreme” as we typically think of it.

The most common addict in our society is a smoker

likely a fully functioningindividual

little noticeable intoxication

withdrawal syndrome is notphysically life-threatening

However, because of smoking'shealth-related complications, itis the number 1 cause ofpreventable death in the U.S.

Addiction to highly-palatable,processed foods may resemblenicotine addiction

Does the title of a “food addict” confer stigma?

\

Nicole Avena

10

Summary

Allen et al. (2012)

Thank you!

Contact:

na2574@columbia.edu

Collaborators:

Mark Gold

Pedro Rada

Sarah Leibowitz

Students:

Miriam Bocarsly

Susan Murray

Alastair Tulloch

Monica Gordillo

Eric Su

Stephanie Yarnell

Elyse Powell

Nicole Avena