Behavioral addiction

Addiction and dependence glossary
• addiction – a state characterized by compulsive engagement in rewarding stimuli despite adverse consequences
• addictive behavior – a behavior that is both rewarding and reinforcing
• addictive drug – a drug that is both rewarding and reinforcing
• dependence – an adaptive state associated with a withdrawal syndrome upon cessation of repeated exposure to a stimulus (e.g., drug intake)
• drug sensitization or reverse tolerance – the escalating effect of a drug resulting from repeated administration at a given dose
• drug withdrawal – symptoms that occur upon cessation of repeated drug use
• physical dependence – dependence that involves persistent physical–somatic withdrawal symptoms (e.g., fatigue and delirium tremens)
• psychological dependence – dependence that involves emotional–motivational withdrawal symptoms (e.g., dysphoria and anhedonia)
• reinforcing stimuli – stimuli that increase the probability of repeating behaviors paired with them
• rewarding stimuli – stimuli that the brain interprets as intrinsically positive or as something to be approached
• sensitization – an amplified response to a stimulus resulting from repeated exposure to it
• tolerance – the diminishing effect of a drug resulting from repeated administration at a given dose

Behavioral addiction is a form of addiction that involves a compulsion to engage in a rewarding non-drug-related behavior – sometimes called a natural reward – despite any negative consequences to the person's physical, mental, social or financial well-being. A gene transcription factor known as ΔFosB has been identified as being the critical progenitor of behavioral and drug addictions, which are associated with the same set of neural adaptations in the reward system.

Biomolecular mechanisms

Main article: ΔFosB

ΔFosB, a gene transcription factor, has been identified as playing a critical role in the development of addictive states in both behavioral addictions and drug addictions. Overexpression of ΔFosB in the nucleus accumbens is necessary and sufficient for many of the neural adaptations seen in drug addiction; it has been implicated in addictions to alcohol, cannabinoids, cocaine, nicotine, phenylcyclidine, and substituted amphetamines as well as addictions to natural rewards such as sex, exercise, and food. A recent study also demonstrated a cross-sensitization between drug reward (amphetamine) and a natural reward (sex) that was mediated by ΔFosB.

Besides increased ΔFosB expression in the nucleus accumbens, there are many other correlations in the neurobiology of behavioral addictions with drug addictions.

One of the most important discoveries of addictions has been the drug based reinforcement and, even more important, reward based learning processes. Several structures of the brain are important in the conditioning process of behavioral addiction; these subcortical structures form the brain regions known as the reward system. One of the major areas of study is the amygdala, a brain structure which involves emotional significance and associated learning. Research shows that dopaminergic projections from the ventral tegmental area facilitate a motivational or learned association to a specific behavior. Dopamine neurons take a role in the learning and sustaining of many acquired behaviors. Research specific to Parkinson’s disease has led to identifying the intracellular signaling pathways that underlie the immediate actions of dopamine. The most common mechanism of dopamine is to create addictive properties along with certain behaviors. There are three stages to the dopamine reward system: bursts of dopamine, triggering of behavior, and further impact to the behavior. Once electronically signaled, possibly through the behavior, dopamine neurons let out a ‘burst-fire’ of elements to stimulate areas along fast transmitting pathways. The behavior response then perpetuates the striated neurons to further send stimuli. The fast firing of dopamine neurons can be monitored over time by evaluating the amount of extracellular concentrations of dopamine through micro dialysis and brain imaging. This monitoring can lead to a model in which one can see the multiplicity of triggering over a period of time. Once the behavior is triggered, it is hard to work away from the dopamine reward system.

Behaviors like gambling have been linked to the new found idea of the brain’s capacity to anticipate rewards. The reward system can be triggered by early detectors of the behavior, and trigger dopamine neurons to begin stimulating behaviors. But in some cases, it can lead to many issues due to error, or reward-prediction errors. These errors can act as teaching signals to create a complex behavior task over time.

Summary of addiction-related plasticity

Form of neural or behavioral plasticity	Type of reinforcer						Sources
	Opiates	Psychostimulants	High fat or sugar food	Sexual intercourse	Physical exercise (aerobic)	Environmental enrichment
ΔFosB expression in nucleus accumbens D1-type MSNs	↑	↑	↑	↑	↑	↑
Behavioral plasticity
Escalation of intake	Yes	Yes	Yes
Psychostimulant cross-sensitization	Yes	Not applicable	Yes	Yes	Attenuated	Attenuated
Psychostimulant self-administration	↑	↑	↓		↓	↓
Psychostimulant conditioned place preference	↑	↑	↓	↑	↓	↑
Reinstatement of drug-seeking behavior	↑	↑			↓	↓
Neurochemical plasticity
CREB phosphorylation in the nucleus accumbens	↓	↓	↓		↓	↓
Sensitized dopamine response in the nucleus accumbens	No	Yes	No	Yes
Altered striatal dopamine signaling	↓DRD2, ↑DRD3	↑DRD1, ↓DRD2, ↑DRD3	↑DRD1, ↓DRD2, ↑DRD3		↑DRD2	↑DRD2
Altered striatal opioid signaling	↑μ-opioid receptors	↑μ-opioid receptors ↑κ-opioid receptors	↑μ-opioid receptors	↑μ-opioid receptors	No change	No change
Changes in striatal opioid peptides	↑dynorphin	↑dynorphin	↓enkephalin		↑dynorphin	↑dynorphin
Mesocorticolimbic synaptic plasticity
Number of dendrites in the nucleus accumbens	↓	↑		↑
Dendritic spine density in the nucleus accumbens	↓	↑		↑

Psychiatric and medical classifications

Diagnostic models do not currently include the criteria necessary to identify behaviors as addictions in a clinical setting. Behavioral addictions has been proposed as a new class in DSM-5, but the only category included is gambling addiction. Internet gaming addiction is included in the appendix as a condition for further study.

Behavioral addictions, which are sometimes referred to as impulse control disorders, are increasingly recognized as treatable forms of addiction. The type of excessive behaviors identified as being addictive include gambling, food, sexual intercourse, use of pornography, use of computers, playing video games, use of the internet, exercise, and shopping.

Researching addiction to food, for example, a 2009 Scripps Research Institute study found evidence that the same molecular mechanisms correlated with human drug addiction also exist in compulsive overeating in obese rats. The dopamine D₂ receptor studied is associated with vulnerability to drug addiction in humans. It was found downregulated in obese rats exposed to a high fat diet, and further reductions of the receptor increased compulsive eating. The D₂ receptor responds to dopamine, a central neurotransmitter released in anticipation of rewarding, satiating experiences such as those involving food, sex or psychoactive drugs.

On August 15, 2011 the American Society of Addiction Medicine (ASAM) issued a public statement defining all addiction in terms of brain changes. "Addiction is a primary, chronic disease of brain reward, motivation, memory and related circuitry."

The following excerpts are taken from the organization's FAQs:

The new ASAM definition makes a departure from equating addiction with just substance dependence, by describing how addiction is also related to behaviors that are rewarding. This is the first time that ASAM has taken an official position that addiction is not solely "substance dependence." This definition says that addiction is about functioning and brain circuitry and how the structure and function of the brains of persons with addiction differ from the structure and function of the brains of persons who do not have addiction. It talks about reward circuitry in the brain and related circuitry, but the emphasis is not on the external rewards that act on the reward system. Food and sexual behaviors and gambling behaviors can be associated with the "pathological pursuit of rewards" described in this new definition of addiction.

We all have the brain reward circuitry that makes food and sex rewarding. In fact, this is a survival mechanism. In a healthy brain, these rewards have feedback mechanisms for satiety or 'enough.' In someone with addiction, the circuitry becomes dysfunctional such that the message to the individual becomes ‘more’, which leads to the pathological pursuit of rewards and/or relief through the use of substances and behaviors. So, anyone who has addiction is vulnerable to food and sex addiction.

Since ASAM released its statement, and shortly before its release, additional new studies have come out on Internet addiction. They reveal the same fundamental brain changes seen in other addicts of drugs. Another 2011 study found that the risk of Internet addiction in men was about three times more than women. Researchers noted,

Internet addiction is a psychosocial disorder and its characteristics are as follows: tolerance, withdrawal symptoms, affective disorders, and problems in social relations. Internet usage creates psychological, social, school and/or work difficulties in a person's life. Eighteen percent of study participants were considered to be pathological Internet users, whose excessive use of the Internet was causing academic, social, and interpersonal problems. Excessive Internet use may create a heightened level of psychological arousal, resulting in little sleep, failure to eat for long periods, and limited physical activity, possibly leading to the user experiencing physical and mental health problems such as depression, OCD, low family relationships and anxiety.

Treatment

Behavioral addiction is a treatable condition. Treatment options include psychotherapy and psychopharmacology (medications) or a combination of both. Cognitive behavioral therapy (CBT) is the most common psychotherapeutic modality used with behavioral addiction clients; it focuses on identifying patterns of abuse and making lifestyle changes to healthier behaviors. Currently, there are no medications approved for treatment of behavioral addiction but some medications used for treatment of drug addiction may also be beneficial with behavioral addictions.

Research

Another growing area is social media addiction. Psychology researchers surveyed 253 undergraduate students at the University of Albany and found that not only is social media (particularly Facebook) itself potentially addictive, those who use it may also be at greater risk for substance abuse.

See also

• Addictive behavior
• Addictive personality
• Habit
• ANKK1#Addictive behaviors