Personality theories of addiction

Personality theories of addiction are

Key to this concept is the Hedonic Hypothesis, which states that individuals initiate use of the substance or behaviour for their pleasurable effects, but then take it compulsively to avoid withdrawal symptoms, resulting in dependence.[16] Based on this hypothesis, some researchers believe that individuals engaging in risky use of substances or behaviours may be over-responding to negative stimuli, which leads to addiction.

Negative affect has also been a powerful predictor in terms of vulnerability to addiction in adolescents. High-risk adolescents have been found to be highly reactive to negative stimuli, which increases their motivation to engage in substance use following a negative emotion-arousing situation.^[17] Moreover, it has been established that adolescents high in negative affect are at increased risk for moving from recreational use to problematic use despite a family history of addiction.^[17]

Furthermore, the trait negative urgency, the propensity to engage in risky behaviour in response to distress, is highly predictive of certain aspects of substance abuse in adolescents.^[18] Early individual differences in emotional differences in reactivity and regulation underlie the later emergence of the trait 'negative urgency'.^[19]

Positive affect

Unlike negative affect, positive affect is related to addiction in both high and low forms. For example, individuals high in positive affect are more likely to engage in risky behaviour, such as drug use. Individuals with high positive affect in response to use are more likely to seek out substances for

Extensive personality research has been done that links positive emotional states to individual differences in risky behaviour.[1] The trait 'positive urgency', defined as the tendency to engage in risky behaviour under conditions of extreme positive affect, is predictive of substance or behavioural problems that lead to addiction.^[20] This trait represents an underlying dysregulation in response to extreme affective states and has a direct impact on behaviour. The trait 'positive urgency' has been shown to have a predictive relationship with increases in drinking quantity and alcohol-related problems in college, as well as drug use in college.^[18][21] Furthermore, this trait provides important information on how positive affect can increase the likelihood of engaging in substance abuse.

Another important factor to consider is the individual differences in the experience of pleasurable effects brought on by the substance or behaviour. It is reasoned that certain individuals may be more sensitive to the pleasurable effects and thus experience them with greater intensity, resulting in addiction.^[1] For example, over-responsiveness to substance affects has been found in cocaine addicts – an increased response to methylphenidate in the brain regions associated with emotional reactivity and mood.^[22][23][24] Thus, strong emotional responses that addicted individuals show in response to substances or behaviours might be results of enhanced sensitivity to their effects.

Individuals differ in the way by which they

Many addicts report symptoms of anhedonia (i.e., the inability to experience pleasure).^[26] Results of chronic deviation of the brain's reward set point, which follow a prolonged intoxication, diminish responsiveness to natural positive stimuli. This may result in an over-responsiveness to substance-related cues, coupled with an impaired capacity to initiate behaviours in response to natural rewards.^[27] Thus, low positive affect inhibits the individual's ability to replace drug-taking with other rewarding activities. It has also been proposed that during substance dependence the somatic states that guide decision-making are weakened in relation to natural rewards, while at the same time they enhance the emotional response to drug-related stimuli.^[28]

Compulsive behaviours characterized by addiction are underpinned by two interacting systems:

1. impulsivity; responsible for the rapid signalling of the affective importance of a stimuli
2. reflection; cognitively evaluates the signal before altering the behavioural response.

Dysfunction in impulsivity exaggerates the emotional impact of the drug-related stimuli and attenuates the impact of natural reinforcement.^[1] Dysregulation in reflection results in the inability to override impulsivity, thus resulting in addiction.^[1] Under-responsiveness to naturally occurring positive stimuli is a crucial element that biases the individual towards the use of substances or behaviours and away from non-drug alternatives.

Effortful control

Temperamental effortful control is defined as the ability to suppress a dominant response in order to perform a subdominant response.^[29] In other words, it is the degree of control the individual has over impulses and emotions, which includes the ability to focus or shift attention. Temperamental effortful control can influence addiction in a number of ways.

Low levels of effortful control can render the individual less able to distract themselves from unpleasant feelings or overcome strong affective impulses, resulting in maladaptive responses to distress – such as continued substance use.^[1] Low effortful control may also interact with negative and positive affect, predisposing individuals to substance or behavioural use, and impair their ability to control use.^[1]

A general inability to control affective states may impair the conditioning of behaviour associated with rewards and punishment, may increase susceptibility to biasing by substance-related cues, and could tax self-regulatory capacity.^[1] Such conditions may render individuals unable to interrupt automatic drug-seeking behaviours. Abnormal levels of positive and negative affect can be increased by low effortful control.^[30][31] For example, high positive affect may interact with low effortful control in increasing risk of addiction amongst vulnerable populations.

Gray's reinforcement sensitivity theory

Gray's

According to this model, substance abuse problems may arise under two different personality traits: low BIS and high BAS. Since the BAS promotes the individual to pursue actions that may result in reward, BAS sensitivity is involved in the initiation of addiction. Significant associations have been found between high BAS such as alcohol misuse in school girls, hazardous drinking in men, illicit drug abuse, and tobacco use. BAS sensitivity is a significant predictor of reactivity to substance cues, or cravings.[5]^{[37][38][39][40][41]} Conversely, BIS sensitivity is involved in avoiding negative situations or affect (such as withdrawal). Low BIS has been positively associated with continuing the addiction to relieve feelings of withdrawal, or for continued use to alleviate negative affect.

Model of impulsivity

The model of impulsivity states that individuals high in impulsivity are at greater risk of addictive behaviours. The model proposes a two dimensional trait characteristic for the initiation and continuation of substance/behavioural abuse:

• Reward Drive (RD) – reflects individual differences in sensitivities to incentive motivation and engagement of addictive behaviour when reward cues are detected.^[6]
• Rash Impulsiveness (RI) – reflecting individual differences in the ability to modify the addictive behaviour due to negative consequences.^[6] Individuals high in RI are oblivious or insensitive to the negative consequences as a result of addictive behaviour when engagement is craved.

Both high RD and RI individuals are found to have difficulty in making decisions that have future consequences. Individuals high in RD experience greater reinforcement when initially engaging in the addictive behaviour, and experience stronger conditioned associations with continued use. Individuals high in RI experience greater difficulty resisting

Five factor model

The five factors are:

• O Openness to experience (inventive/curious vs. consistent/cautious)
• C Conscientiousness (efficient/organized vs. easy-going/careless)
• E Extraversion (outgoing/energetic vs. solitary/reserved)
• A Agreeableness (friendly/compassionate vs. challenging/detached)
• N Neuroticism (sensitive/nervous vs. secure/confident)

Data analysis demonstrated that higher scores for N and O, and lower scores for C and A, lead to increased risk of drug use.

belong to the type N${\displaystyle \Uparrow }$, C${\displaystyle \Downarrow }$ (Insecures) and do not belong to the type E${\displaystyle \Uparrow }$, C${\displaystyle \Downarrow }$ (Impulsives, Hedonists). On the contrary, users of

belong to the type E${\displaystyle \Uparrow }$, C${\displaystyle \Downarrow }$ and do not belong to the type N${\displaystyle \Uparrow }$, C${\displaystyle \Downarrow }$. Detailed comparison of ecstasy and heroin users demonstrates that they are significantly different.

Volatile substance abuse

.

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