do behavioural and substance addictions share the same mechanisms Flashcards
Intro
Addiction can be defined as behaviour than changes from a habit to an obligation (Alavi et al 2012). It is suggested that all articles capable of stimulating an individual can be addictive. Further, various findings indicate that there are a number of similarities as well as some differences between drug addiction and behavioural addictions. For instance, patients suffering from behavioural addictions have been found to describe addiction specific phenomena such as cravings, excessive behaviour, physical and psychological withdrawal symptoms, loss of control, development of tolerance and inducing and perceiving expected psychotropic effects (Alavi et al 2010). The following essay will be discussing whether behavioural addictions are influenced by the same neurological and psychological mechanisms involved in addiction to substances. As such, the essay will be using a compare and contrast approach in which influences of behavioural addictions, specifically problem gambling and video gaming will be contrasted to substance addiction such as cocaine and alcohol.
Describe problem gambling
o Persistent and recurrent problematic gambling behavior leading to clinically significant impairment or distress, such as Needs to gamble with increasing amounts of money in order to achieve the desired excitement, Has made repeated unsuccessful efforts to control, cut back, or stop gambling, After losing money gambling, often returns another day to get even (“chasing” one’s losses). o Problem gambling rates at 0.9% of the adult population i.e. ~450,000 adults in UK
o 6% of regular gamblers classified as high-time/high-spend gamblers, These gamblers had lower SES and more adverse living conditions
• Crisp et al 2004 Study in Australia. Women actually make up almost half (46%) of problem gamblers who sought advice from a free counselling service in Australia. However, females using this service tended to be older than males (40yrs vs 36yrs) and reported on average less than half the amount of gambling debts reported by males (A$ 19,000).
• Women also tend to have longer term gambling problems than women, who tend to quit after about 5 to 10 years of addiction
Describe video gaming problem
- Difficult to obtain statistics as this is currently no diagnostic criteria for this disorder and there are many different types of experiences from gaming.
- Ferguson et al (2011) suggest prevalence estimates of ~6%, but varies as function of methodology used
- Some studies find that problematic gaming is associated with poorer mental health.
- Stetina et al 2011 Results indicate that those who play multi-player role-playing games show more often problematic gaming behavior, depressive tendencies and lower self-esteem compared to users playing other online-games. MMORPG users reported to playing significantly more often in order to escape from real-life problems, which might be a valuable coping strategy but might also lead to problematic gaming behavior.
Study showing dopamine activity in gambling
Ko et al 2009 The aim of this study was to identify the neural substrates of online gaming addiction through evaluation of the brain areas associated with the cue-induced gaming urge. Ten participants with online gaming addiction and 10 control subjects without onlinegaming addiction were tested. They were presented with gaming pictures and the paired mosaic pictures while undergoing functional magnetic resonance imaging (fMRI) scanning. Right orbitofrontal cortex, right nucleus accumbens, bilateral anterior cingulate and medial frontal cortex, right dorsolateral prefrontal cortex, and right caudate nucleus were activated in the addicted group in contrast to the control group. The activation of the region-of-interest (ROI) defined by the above brain areas was positively correlated with self-reported gaming urge and recalling of gaming experience provoked by the WOW pictures. The results demonstrate that the neural substrate of cue-induced gaming urge/craving in online gaming addiction is similar to that of the cue-induced craving in substance dependence in that dopamine rewarrd pathways are activate. Thus, the results suggest that the gaming urge/craving in online gaming addiction and craving in substance dependence might share the same neurobiological mechanism i.e. mesocorticolimbic DA pathways. However, a notable aspect of these results i that there was no activation of the striatum, which is often activated in substance use dopamine reward.
Study showing how exactly dopamine reward works in gambling
Linnet et al 2010. Pathological gamblers (PG) often continue gambling despite losses, known as ‘chasing one’s losses’. We therefore hypothesized that losing money would be associated with increased dopamine release in the ventral striatum of PG compared with healthy controls (HC). PG who lost money had significantly increased dopamine release in the left ventral striatum compared with HC. PG and HC who won money did not differ in dopamine release. Our findings suggest a dopaminergic basis of monetary losses in pathological gambling, which might explain loss-chasing behavior. This shows that striatal increases in dopamine only occur conditionally in gambling, whereas in drug addiction the reward is fairly consistent with each administration (although it may decrease gradually with chronic use).
Study showing exactly how dopamine works in substance abuse
Dopamine neurotransmission in the ventromedial striatum (VMS) mediates acute reinforcing effects of abused drugs, but with protracted use the dorsolateral striatum is thought to assume control over drug seeking. We measured striatal dopamine release during a cocaine self-administration regimen that produced escalation of drug taking in rats. Surprisingly, we found that phasic dopamine decreased in both regions as the rate of cocaine intake increased, with the decrement in dopamine in the VMS significantly correlated with the rate of escalation. Administration of the dopamine precursor L-DOPA at a dose that replenished dopamine signaling in the VMS reversed escalation, thereby demonstrating a causal relationship between diminished dopamine transmission and excessive drug use. Together these data provide mechanistic and therapeutic insight into the excessive drug intake that emerges following protracted use
Study showing diminished DA receptor availability in striatum in drug use
Nader et al 2006- Dopamine neurotransmission is associated with high susceptibility to cocaine abuse. Positron emission tomography was used in 12 rhesus macaques to determine if dopamine D2 receptor availability was associated with the rate of cocaine reinforcement, and to study changes in brain dopaminergic function during maintenance of and abstinence from cocaine. Baseline D2 receptor availability was negatively correlated with rates of cocaine self-administration. D2 receptor availability decreased by 15–20% within 1 week of initiating self-administration and remained reduced by ∼20% during 1 year of exposure. Long-term reductions in D2 receptor availability were observed, with decreases persisting for up to 1 year of abstinence in some monkeys. These data provide evidence for a predisposition to self-administer cocaine based on D2 receptor availability, and demonstrate that the brain dopamine system responds rapidly following cocaine exposure.
Study showing DA receptor availability in problem gamblers
Clark et al 2012 The aim of the present study was to assess striatal dopamine D2/D3 receptor availability in PG, and its association with trait impulsivity. Males with PG (n = 9) and male healthy controls (n = 9) underwent [11C]-raclopride positron emission tomography imaging and completed the UPPS-P impulsivity scale. There was no significant difference between groups in striatal dopamine D2/D3 receptor availability, in contrast to previous reports in drug addiction. However, mood-related impulsivity (‘Urgency’) was negatively correlated with [11C]-raclopride binding potentials in the PG group. The absence of a group difference in striatal dopamine binding implies a distinction between behavioural addictions and drug addictions. Nevertheless, our data indicate heterogeneity in dopamine receptor availability in disordered gambling, such that individuals with high mood-related impulsivity may show differential benefits from dopamine-based medications.
Striatal dopamine in internet addiction- study
Kim et al 2011- We hypothesized that Internet addiction would be associated with reduced levels of dopaminergic receptor availability in the striatum compared with controls. To test this hypothesis, a radiolabeled ligand [¹¹C]raclopride and positron emission tomography was used to assess dopamine D2 receptor binding potential in men with and without Internet addiction. Consistent with our prediction, individuals with Internet addiction showed reduced levels of dopamine D2 receptor availability in subdivisions of the striatum including the bilateral dorsal caudate and right putamen. This finding contributes to the understanding of neurobiological mechanism of Internet addiction.
Conclusion about differences between behavioural and substance addictions
In conclusion, research has shown that the mesolimbic dopamine pathway is activated similarly in substance addictions and behavioural addictions, indicating that they have similar neurobiological underpinnings. However, the striatum, which is also consistently implicated in dopamine response to drug addiction, is not consistently activated in gambling. This may be due to the nature of gambling itself, which is that winning and losing are likely to elicit different responses. Thus, findings how that striatal dopamine release only occurs in gambling following a loss. This rewarded loss also helps to explain ‘chasing losses’ seen in probblem gamling. However, this differing dopamine response does not mean that all behavioural addictions are neurbiologically different from substance addictions. For example, internet addiction seems to have similar dopamine responses.
