Alcoholics Anonymous and Reduced Impulsivity: A Novel Mechanism of Change

Impulsivity or lack of behaviour inhibition, especially when distressed, is one psychological mechanisms which is implicated in all addictive behaviour from substance addiction to behaviour addiction.

It is, in my view, linked to the impaired emotion processing as I have elucidated upon in various blogs on this site.

This impulsivity is present for example in those vulnerable to later alcoholism, i.e. sons and daughters of alcoholic parents or children  from a family that has a relatively high or concentrated density of alcoholics in the family history, right through to old timers, people who have decades of recovery from alcoholism.

It is an ever present and as a result part of a pathomechanism of alcoholism, that is it is fundamental to driving alcoholism to it’s chronic endpoint.

It partly drives addiction via it’s impact on decision making – research shows people of varying addictive behaviours choose now over later, even if it is a smaller short term gain over a greater long term gain. We seem to react to relieve a distress signal in the brain rather than in response to considering and evaluating the long term consequences of a decision or act.

No doubt this improves in recovery as it has with me. Nonetheless, this tendency for rash action with limited consideration of long term consequence is clearly a part of the addictive profile. Not only do we choose now over then, we appear to have an intolerance of uncertainty, which means we have difficulties coping with uncertain outcomes. In other words we struggle with things in the future particularly if they are worrying or concerning things, like a day in court etc. The future can continually intrude into the present. A thought becomes a near certain action, again similar to the though-action fusion of obsessive compulsive disorder. It is as if the thought and possible future action are almost fused, as if they are happening in unison.

Although simple, less worrying events can also make me struggle with leaving the future to the future instead of endless and fruitlessly ruminating about it in the now. In early recovery  especially I found that I had real difficulty dealing with the uncertainty of future events and always thought they would turn out bad. It is akin to catastrophic thinking.

If a thought of a drink entered into my head it was so distressing, almost as if I was being dragged by some invisible magnet to the nearest bar. It was horrendous. Fortunately I created my own thought action fusion to oppose this.

Any time I felt this distressing lure of the bar like some unavoidable siren call of alcohol I would turn that thought into the action of ringing my sponsor. This is why sponsees should ring sponsors about whatever, whenever in order to habitualize these responses to counteract the automatic responses of the addicted brain.

I think it is again based on an inherent emotion dysregulation. Obsessive thoughts are linked to emotion dysregulation.

My emotions can still sometimes control me and not the other way around.

Apparently we need to recruit the frontal part of the brain to regulate these emotions and this is the area most damaged by chronic alcohol consumption.

As a result we find it difficult to recruit this brain area which not only helps regulate emotion but is instrumental in making reflective, evaluative decisions about future, more long term consequence. As a result addicts of all types appear to use a “bottom up” sub-cortical part of the brain centred on the amgydala region to make responses to decisions instead of a “top down” more cortical part of the brain to make evaluative decisions.

We thus react, and rashly act to relieve the distress of undifferentiated emotions, the result of unprocessed emotion rather than using processed emotions to recruit the more cortical parts of the brain.

Who would have though emotions were so instrumental in us making decisions? Two parts of the brain that hold emotions in check so that they can be used to serve goal directed behaviour are the orbitofrontal cortex and the ventromedial prefrontal cortex.

120px-Orbital_gyrus_animation_small2

 

These areas also keep amgydaloid responding in check. Unfortunately these two areas are impaired in alcoholics and other addictive behaviours so their influence on and regulation of the amgydala is also impaired.

This means the sub cortical areas of the amgydala and related regions are over active and prompt not a goal directed response to decision making but a “fight or flight” response to alleviate distress and not facilitate goal directed behaviour.

128px-Amyg

 

Sorry for so much detail. I have read so much about medication recently which does this or that to reduce craving or to control  drinking but what about the underlying conditions of alcoholism and addictive behaviour? These are rarely mentioned or considered at all.

 

We always in recovery have to deal with alcoholism not just it’s symptomatic manifestation of that which is chronic alcohol consumption. This is a relatively simple point and observation that somehow alludes academics, researchers and so-called commentators on this fascinating subject.

Anyway that is some background to this study which demonstrates that long term AA membership can reduce this impulsivity and perhaps adds validity to the above arguments that improved behaviour inhibition and reducing impulsivity is a very possible mechanism of change brought about by AA membership and the 12 step recovery program.

It shows how we can learn about a pathology from the recovery from it!

Indeed when one looks back at one’s step 4 and 5 how many times was this distress based impulsivity the real reason for “stepping on the toes of others” and for their retaliation?

Were we not partly dominated by the world because we could not keep ourselves in check? Didn’t all our decisions get us to AA because they were inherently based on a decision making weakness? Isn’t this why it is always useful to have a sponsor, someone to discuss possible decisions with?

Weren’t we out of control, regardless of alcohol or substance or behaviour addiction? Isn’t this at the heart of our unmanageability?

I think we can all see how we still are effected by a tendency not to think things through and to act rashly.

The trouble it has caused is quite staggeringly really?

Again we cite a study (1) which has Rudolf H. Moos as a co-author. Moos has authored and co-authored a numbered of fine papers on the effectiveness of AA and is a rationale beacon in a sea of sometimes quite controversial and ignorant studies on AA, and alcoholism in general.

“Abstract

Reduced impulsivity is a novel, yet plausible, mechanism of change associated with the salutary effects of Alcoholics Anonymous (AA). Here, we review our work on links between AA attendance and reduced impulsivity using a 16-year prospective study of men and women with alcohol use disorders (AUD) who were initially untreated for their drinking problems. Across the study period, there were significant mean-level decreases in impulsivity, and longer AA duration was associated with reductions in impulsivity…

Among individuals with alcohol use disorders (AUD), Alcoholics Anonymous (AA) is linked to improved functioning across a number of domains [1, 2]. As the evidence for the effectiveness of AA has accumulated, so too have efforts to identify the mechanisms of change associated with participation in this mutual-help group [3]. To our knowledge, however, there have been no efforts to examine links between AA and reductions in impulsivity-a dimension of personality marked by deficits in self-control and self-regulation, and tendencies to take risks and respond to stimuli with minimal forethought.

In this article, we discuss the conceptual rationale for reduced impulsivity as a mechanism of change associated with AA, review our research on links between AA and reduced impulsivity, and discuss potential implications of the findings for future research on AA and, more broadly, interventions for individuals with AUD.

Impulsivity and related traits of disinhibition are core risk factors for AUD [5, 6]. In cross-sectional research, impulsivity is typically higher among individuals in AUD treatment than among those in the general population [7] and, in prospective studies, impulse control deficits tend to predate the onset of drinking problems [811]

Although traditionally viewed as static variables, contemporary research has revealed that traits such as impulsivity can change over time [17]. For example, traits related to impulsivity exhibit significant mean- and individual-level decreases over the lifespan [18], as do symptoms of personality disorders that include impulsivity as an essential feature [21, 22]. Moreover, entry into social roles that press for increased responsibility and self-control predict decreases in impulsivity [16, 23, 24]. Hence, individual levels of impulsivity can be modified by systematic changes in one’s life circumstances [25].

Substance use-focused mutual-help groups may promote such changes, given that they seek to bolster self-efficacy and coping skills aimed at controlling substance use, encourage members to be more structured in their daily lives, and target deficits in self-regulation [26]. Such “active ingredients” may curb the immediate self-gratification characteristic of disinhibition and provide the conceptual grounds to expect that AA participation can press for a reduction in impulsive inclinations.

…the idea of reduced impulsivity as a mechanism of change…it is consistent with contemporary definitions of recovery from substance use disorders that emphasize improved citizenship and global health [31], AA’s vision of recovery as a broad transformation of character [32], and efforts to explore individual differences in emotional and behavioral functioning as potential mechanisms of change (e.g., negative affect [33,34]).

Several findings are notable from our research on associations between AA attendance and reduced impulsivity. First, consistent with the idea of impulsivity as a dynamic construct [18, 19], mean-levels of impulsivity decreased significantly in our AUD sample. Second, consistent with the notion that impulsivity can be modified by contextual factors [25], individuals who participated in AA longer tended to show larger decreases in impulsivity across all assessment intervals.

References

Blonigen, D. M., Timko, C., & Moos, R. H. (2013). Alcoholics anonymous and reduced impulsivity: a novel mechanism of change. Substance abuse, 34(1), 4-12.

Explaining the negative consequences of Negative Urgency.

Explaining how negative Negative Urgency can be.

from Inside the Alcoholic Brain by alcoholicsguide

In various blogs we have suggested that one of the main aspects of addictive behaviours is to act as the result of distress-based impulsivity or negative urgency. Here we explore in more details what we mean by that term negative urgency.

Here we borrow from one article (1) which has an excellent review of  negative urgency (1).

The experience of emotion facilitates action. It has long been recognized that emotional processing appears to prepare the body for action (Frijda, 1986; Lang, 1993; Saami, Mumme, & Campos, 1998). In fact, to emote means, literally, to prepare for action (Maxwell & Davidson, 2007). Researchers have theorized that the relationship between emotional experiences and actions involve activation of the motor cortex by limbic structures (Morgenson, Jones, & Yim, 1980).

Some investigations have used neuroimaging techniques to document increased activity in motor areas of the brain during emotional processing (Bremner et al., 1999; Rauch et al., 1996), and nonhuman studies suggest the emotion-action interface may involve connections between the amygdala and the anterior cingulate cortex (ACC: Devinsky, Morrel, & Vogt, 1995).

Hajcak et al. (2007) found that emotionally arousing stimuli increase motor cortex excitability. The authors theorized that there may be individual difference in emotional reactivity that may relate to differences in the amount of activation of the motor cortex areas.

One takes action to meet the need identified by the emotion.Pinker (1997) makes this point by noting that “Most artificial intelligence researchers believe that freely behaving robots . . . will have to be programmed with something like emotions merely for them to know at every moment what to do next” (p. 374).

Intense emotions can undermine rational, advantageous decision making (Bechara, 2004, 2005;Dolan, 2007; Driesbach, 2006; Shiv et al., 2005). It also appears to be true that attempts to regulate negative emotions can impair one’s ability to continue self-control behaviors (Muraven & Baumeister, 2000; Tice & Bratslavsky, 2000; Tice,Bratslavsky, & Baumeister, 2001).

Thus, it is not surprising that individuals engage in other strategies to manage intense emotions that are ill-considered and maladaptive, in that they work against one’s long-term interests. For example, heavy alcohol use may be used to manage emotion. Daily diary studies of alcohol use indicate that individuals drink more on days when they experience anxiety and stress (Swendson et al., 2000).

Indeed, negative affect states have been shown to correlate with a greater frequency of many maladaptive, addictive behaviors, including alcohol and drug abuse (Colder & Chassin, 1997;Cooper, 1994; Cooper et al., 2000; Martin & Sher, 1994;Peveler & Fairburn, 1990). This pattern also is true of bulimic behaviors; individuals tend to participate in more binge eating and purging behaviors on days during which they experienced negative emotions (Agras & Telch, 1998; Smyth et al., 2007). Emotions such as shame, guilt, anger, depression, loneliness, stress, anxiety, boredom, and rejection are often cited as triggers for binge and purge episodes (Jeppson, Richards, Hardman, & Granley, 2003). For bulimic women, engaging in binge eating produces a decline in the earlier negative emotion (Smyth et al., 2007). Because actions like these do appear to reduce negative affect, they are reinforced.

Brain Pathways Related to Emotion-Based Action

Brain system involved in emotion and action -the amygdala, the orbitofrontal cortex (OFC) and its medial sector (the ventromedial prefrontal cortex, or VM PFC:Bechara, 2005), and other areas of the prefrontal cortex (PFC:Barbas, 2007). The amygdala appears to be heavily involved in the experience of negative affect; more broadly, it is thought to play a role in directing attention to emotionally salient stimuli, particularly stressful or disturbing stimuli (Davidson, 2003).

orbitofrontaler_cortex

The OFC appears to be involved in the modulation of emotion-based reactivity (Davidson, 2003).

OFC activity overrides emotional responses, apparently by providing information and a bias toward long-term, goal-directed behavior (Lewis & Todd, 2007).

Davidson and his colleagues (Davidson, 1998, 2000,2003;Davidson & Irwin, 1999; Davidson, Putnam, & Larson, 2000) suggest the experience of intense emotion, and its accompanying potential actions, is inconsistent with one’s long-term goals. The OFC, perhaps particularly the left VM PFC, provides a biasing signal to avoid immediate reward, and thus maintain one’s pursuit of one’s longer-term goals. Davidson (2003) refers to this process as affect-guided planning and anticipation: with healthy left VMPFC functioning, one gains access to the emotion associated with anticipated outcomes consistent with one’s long-term goals. The ability to do so is, Davidson argues, the hallmark of adaptive, emotion-based decision making. At times, long-term affect-guided planning is difficult: the experience of intense emotions unrelated to one’s long-term interests may disrupt processing with regard to those interests (Gray, 1999; Preston, Buchanan, Stansfield, & Bechara, 2007). But healthy functioning of the left VM PFC helps one maintain an affective connection to one’s longer-term goals, and thus plan accordingly.

Damage to the OFC, and perhaps damage specifically to the VM PFC, results in affective lability and rash action particularly in inhibiting the action of amygdaloid reactivity.

Parasagittal_MRI_of_human_head_in_patient_with_benign_familial_macrocephaly_prior_to_brain_injury_(ANIMATED)

 

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The authors of this study put forward various reasons why OFC and VM PFC damage can cause rash action – we consider these before forwarding our own ideas of why OFC/ VM PFC damage may prompt distress based impulsivity.

The OFC, perhaps particularly the left VM PFC, provides a biasing signal to avoid immediate reward, and thus maintain one’s pursuit of one’s longer-term goals. Davidson (2003) refers to this process as affect-guided planning and anticipation: with healthy left VM PFC functioning, one gains access to the emotion associated with anticipated outcomes consistent with one’s long-term goals. Activation of the left VM PFC also appears to inhibit amygdalar activity (Davidson, 1998), thus shortening the time course of the experience of negative affect and attention to stressful stimuli. Because negative affect stimulates autonomic nervous system (ANS) activity, which provides support for action in response to distress, prolonged negative affect leads to prolonged ANS arousal (Davidson, 2000). Perhaps a greater duration of ANS arousal increases the likelihood of affect-triggered action. Activity in the amygdala appears to facilitate this process.

Damage to the OFC, and perhaps damage specifically to the VM PFC, results in affective lability and rash action. Individuals with PFC damage, and with OFC damage in particular, do not; they do not appear to have the normal anticipatory affective response to potential punishment (Bechara, 2004; Bechara, Tranel, Damasio, & Damasio, 1996; Cardinal et al., 2002).

Thus, OFC damage appears to impair affective anticipation of potential risk to one’s actions.

Bechara, Damasio, Damasio, and Anderson (1994) described OFC-damaged individuals as oblivious to the future consequences of their actions, but sensitive to immediate reinforcement and punishment. Thus, their actions tend to be guided by immediate consequences only. These patients had otherwise retained their intellectual capacities, including abstract reasoning skills. They could even describe possible future consequences in realistic language. They appeared simply to lack the anticipatory affect that others have; thus perhaps lacking the affect-guided anticipation described byDavidson (2003).

The authors then  suggest that  associations between the OFC/VM PFC-amygdala system and psychopathy are  consistent with their claim of an association between this system and the urgency traits. In other words, individuals high in psychopathy have reduced VM PFC functioning, and hence lack an affective connection to the consequences of their actions. Other studies have also documented similar OFC functioning deficits among psychopaths (Blair et al., 2006; Mitchell, Colledge, Leonard, & Blair, 2002).

This model is interesting but there is not mention of stress systems in this model although the authors mention distress and negative affect but not the stress chemicals underpinning these affective manifestations.

The authors also do no mention two hugely important points we believe;

a. that this amgydaloid (hyper) activity, caused by PFC dysfunction can also “offline” PFC activity (fig.1)

b. in favour of the compulsive, emotive-motoric behaviour of the dorsal striatum which drives rash action, distress-based impulsivity or compulsivity rendering the individual remote to negative consequence of actions, although he/she may be able to explain clearly these consequences. prior to or after seeming to not consider them. It is chronic stress dysregulation in addiction that “cuts off” access to action-outcome or goal-directed parts of the brain and recruits stimulus response, implicit, “must do” action instead.

fig 1.

nihms197465f5 (1)

This we believe is the mechanism of negative urgency rather than as the authors suggest in this article, but not included, that VMPFC damage renders individuals unknowing of consequence, when rather, consequence, negative or otherwise, has been cut off by this amygdaolid activity rendering action  outcome associations remote to consciousness.  The brain acts implicitly, procedurally or in a stimulus response way to distress we believe in addictive disorders when heightened amgydaloid reactivity  is in charge of behaviour with VMPFC deficit contributing to this amgydaloid dysfunction.

An argument against simply seeing rash behaviour as the result of OFC or VMPFC damage which leads to lack of knowledge of consequence is that it does not really consider the chronic stress that accompanies addictive behaviours and which creates a near constant distress which acts in the way we describe above.

This does not mean that there is a lack of emotionally guided behaviour or action on the part of addicts. It would appear, as discussed in previous blogs, that emotional processing deficits are common in addiction and may not recruit the goal-directed parts of the brain as the authors suggest. They do not guided action or choices effectively. As a result they manifest in perhaps crude, undifferentiated or processed forms as distress signals instead and recruit more limbic, motoric regions of the brain.  Hence they are not use to anticipate future, long term consequence.

We are simply adding that as addiction becomes more chronic, so does stress and emotional distress and this appears to lead to a distress-based “fight or flight” responding to decision making that the authors have mentioned in this article but not elucidated as above. Addicts increasing appear to recruit sub-cortical or limbic areas in decision making and this is prevalent in abstinence as in active using. it is the consequence of chronic and stress dysregulation.

We suggest that this chronic stress prompts negative urgency via an hypofunctioning ACC (2) and by a “emotional arousal habit bias” as seen in post traumatic stress disorder (3) whereby chronic emotional distress increasingly during the addiction cycle comes to implicitly activate dorsal striatal responding “offlining” the PFC in a similar manner to fig. 1.

References

1. Cyders, M. A., & Smith, G. T. (2008). Emotion-based dispositions to rash action: positive and negative urgency. Psychological bulletin, 134(6), 807.

2. Li, C. S. R., & Sinha, R. (2008). Inhibitory control and emotional stress regulation: neuroimaging evidence for frontal–limbic dysfunction in psycho-stimulant addiction. Neuroscience & Biobehavioral Reviews,32(3), 581-597.

3. Goodman, J., Leong, K. C., & Packard, M. G. (2012). Emotional modulation of multiple memory systems: implications for the neurobiology of post-traumatic stress disorder.

 

What recovers in Recovery? – Cognitive Control over emotions?

A core aspect of alcohol dependence is poor regulation of behavior and emotion.

Alcohol dependent individuals show an inability to manage the appropriate experience and expression of emotion (e.g., extremes in emotional responsiveness to social situations, negative affect, mood swings) (1,2). Dysfunctional emotion regulation has been considered a primary trigger for relapse (1,3) and has been associated with prefrontal dysfunction.

While current alcohol dependence is associated with exaggerated bottom-up (sub-cortical) and compromised top-down (prefrontal cortex) neural network functioning, there is evidence suggesting that abstinent individuals may have overcome these dysfunctional patterns of network functioning (4) .

Neuro-imaging studies showing chronic alcohol abuse to be associated with stress neuroadaptations in the medial prefrontal and anterior cingulate regions of the brain (5 ), which are strongly implicated in the self-regulation of emotion and behavioral self-control (6).

One study (2) looking at how emotional dysregulation related to relapse, showed compared with social drinkers, alcohol-dependent patients reported significant differences in emotional awareness and impulse control during week 1 of treatment. Significant improvements in awareness and clarity of emotion were observed following 5 weeks of protracted abstinence.

Another study (7) which did not look specifically at emotional regulation but rather on the recovering of prefrontal areas of the brain known to be involved also in the inhibition of  impulsive behaviour and emotional regulation showed that differences between the short- and long-abstinence groups in the patterns of functional recruitment suggest different cognitive control demands at different stages in abstinence.

The long-term abstinent group (n=9) had not consumed cocaine for on average 69 weeks, the short-term abstinent (SA) group (n=9) had an average 0f 2.4 weeks.

Relative to controls, abstinent cocaine abusers have been shown to have reduced metabolism in left anterior cingulate cortex (ACC) and right dorsolateral prefrontal cortex (DLPFC), and greater activation in right ACC.

In this study  the abstinent groups of cocaine addicts showed more elevated activity in the DLPFC ; a finding that has also been observed in abstinent marijuana users (8).

The elevation of frontal activity also appears to undergo a shift from the left to right hemisphere over the course of abstinence.  Furthermore, the left inferior frontal gyrus (IFG) has recently been shown to be important for response inhibition (9) and in a task similar to that described here, older adults have been shown to rely more on left PFC (10). Activity observed in these regions is therefore likely to be response inhibition related.

The reliance of the SA group on this region suggests that early in abstinence users may adopt an alternative cognitive strategy in that they may recruit the LIFG in a manner akin to children and older adults to achieve behavioral results similar to the other groups.

In longer,  prolonged abstinence a pattern topographically typical of normal, healthy controls may emerge.
In short-term abstinence there was an increased inhibition-related dorsolateral and inferior frontal activity indicative of the need for increased inhibitory control over behaviour,  while long-term abstinence showed increased error-related ACC activity indicative of heightened behavioral monitoring.
The results suggest that the improvements in prefrontal systems that underlie cognitive control functions may be an important characteristic of successful long-term abstinence.

Another study (11) noted the loss of grey matter in alcoholism that last from 6–9 months to more than a year or, in some reports, up to at least 6 years following abstinence (12 -14).

It has been suggested cocaine abuse blunts responses in regions important to emotional regulation (15)

Given that emotional reactivity has been implicated as a factor in vulnerability to drug abuse (16)  this may be a preexisting factor that  increased the likelihood of the development and prolonging of drug abuse

If addiction can be characterized as a loss of self-directed volitional control (17),  then abstinence (recovery) and its maintenance may be characterized by a reassertion of these aspects of executive function (18)  as cocaine use has been shown to reduce grey matter in brain regions critical to executive function, such as the anterior cingulate, lateral prefrontal, orbitofrontal and insular cortices (19-24) .

The group of abstinent cocaine addicts (11) reported here show elevations in  (increased) grey matter in abstinence exceeded those of the healthy control in this study after 36 weeks, on average, of abstinence .

One possible explanation for this is that abstinence may require reassertion of cognitive control and behavior monitoring that is diminished during current cocaine dependence.

Reassertion of behavioral control may produce a expansion (25)  in grey matter  in regions such as the anterior insula, anterior cingulate, cerebellum, and dorsolateral prefrontal cortex .

All brain regions implicated in the processing and regulating of emotion. 

 

References

 

 

1. Berking M, Margraf M, Ebert D, Wupperman P, Hofmann SG, Junghanns K. Deficits in emotion-regulation skills predict alcohol use during and after cognitive-behavioral therapy for alcohol dependence. J Consult Clin Psychol. 2011;79:307–318.

2.  Fox HC, Hong KA, Sinha R. Difficulties in emotion regulation and impulse control in recently abstinent alcoholics compared with social drinkers. Alcohol Clin Exp Res. 2008;33:388–394.

3..Cooper ML, Frone MR, Russell M, Mudar P. Drinking to regulate positive and negative emotions: A motivational model of alcohol use. J Pers Soc Psychol. 1995;69:990

4. Camchong, J., Stenger, A., & Fein, G. (2013). Resting‐State Synchrony in Long‐Term Abstinent Alcoholics. Alcoholism: Clinical and Experimental Research37(1), 75-85.

5. Sinha, R., & Li, C. S. (2007). Imaging stress- and cue-induced drug and alcohol craving: Association with relapse and clinical
implications. Drug and Alcohol Review, 26(1), 25−31.

6. Beauregard, M., Lévesque, J., & Bourgouin, P. (2001). Neural correlates of conscious self-regulation of emotion. Journal of
Neuroscience, 21(18), RC165

7. Connolly, C. G., Foxe, J. J., Nierenberg, J., Shpaner, M., & Garavan, H. (2012). The neurobiology of cognitive control in successful cocaine abstinence. Drug and alcohol dependence121(1), 45-53.

8.  Tapert SF, Schweinsburg AD, Drummond SP, Paulus MP, Brown SA, Yang TT, Frank LR. Functional MRI of inhibitory processing in abstinent adolescent marijuana users.Psychopharmacology (Berl.) 2007;194:173–183.[PMC free article]

9. Swick D, Ashley V, Turken AU. Left inferior frontal gyrus is critical for response inhibition. BMC Neurosci. 2008;9:102.[PMC free article]

10. Garavan H, Hester R, Murphy K, Fassbender C, Kelly C. Individual differences in the functional neuroanatomy of inhibitory control. Brain Res. 2006;1105:130–142

11. Connolly, C. G., Bell, R. P., Foxe, J. J., & Garavan, H. (2013). Dissociated grey matter changes with prolonged addiction and extended abstinence in cocaine users. PloS one8(3), e59645.

12. Chanraud S, Pitel A-L, Rohlfing T, Pfefferbaum A, Sullivan EV (2010) Dual Tasking and Working Memory in Alcoholism: Relation to Frontocerebellar Circuitry. Neuropsychopharmacol 35: 1868–1878 doi:10.1038/npp.2010.56.

13.  Wobrock T, Falkai P, Schneider-Axmann T, Frommann N, Woelwer W, et al. (2009) Effects of abstinence on brain morphology in alcoholism. Eur Arch Psy Clin N 259: 143–150 doi:10.1007/s00406-008-0846-3.

14.  Makris N, Oscar-Berman M, Jaffin SK, Hodge SM, Kennedy DN, et al. (2008) Decreased volume of the brain reward system in alcoholism. Biol Psychiatry 64: 192–202 doi:10.1016/j.biopsych.2008.01.018.

15, Bolla K, Ernst M, Kiehl K, Mouratidis M, Eldreth D, et al. (2004) Prefrontal cortical dysfunction in abstinent cocaine abusers. J Neuropsychiatry Clin Neurosci 16: 456–464 doi:10.1176/appi.neuropsych.16.4.456.

16.  Piazza PV, Maccari S, Deminière JM, Le Moal M, Mormède P, et al. (1991) Corticosterone levels determine individual vulnerability to amphetamine self-administration. Proc Natl Acad Sci USA 88: 2088–2092. doi: 10.1073/pnas.88.6.2088

17.  Goldstein RZ, Volkow ND (2002) Drug addiction and its underlying neurobiological basis: neuroimaging evidence for the involvement of the frontal cortex. Am J Psychiatry 159: 1642–1652. doi: 10.1176/appi.ajp.159.10.1642

18. Connolly CG, Foxe JJ, Nierenberg J, Shpaner M, Garavan H (2012) The neurobiology of cognitive control in successful cocaine abstinence. Drug Alcohol Depend 121: 45–53 doi:10.1016/j.drugalcdep.2011.08.007.

19.  Liu X, Matochik JA, Cadet JL, London ED (1998) Smaller volume of prefrontal lobe in polysubstance abusers: a magnetic resonance imaging study. Neuropsychopharmacol 18: 243–252 doi:10.1016/S0893-133X(97)00143-7.

20.  Bartzokis G, Beckson M, Lu P, Nuechterlein K, Edwards N, et al. (2001) Age-related changes in frontal and temporal lobe volumes in men – A magnetic resonance imaging study. Arch Gen Psychiatry 58: 461–465. doi: 10.1001/archpsyc.58.5.461

21. Franklin TR, Acton PD, Maldjian JA, Gray JD, Croft JR, et al. (2002) Decreased gray matter concentration in the insular, orbitofrontal, cingulate, and temporal cortices of cocaine patients. Biol Psychiatry 51: 134–142. doi: 10.1016/s0006-3223(01)01269-0

22.  Matochik JA, London ED, Eldreth DA, Cadet J-L, Bolla KI (2003) Frontal cortical tissue composition in abstinent cocaine abusers: a magnetic resonance imaging study. NeuroImage 19: 1095–1102. doi: 10.1016/s1053-8119(03)00244-1

23.  Lim KO, Wozniak JR, Mueller BA, Franc DT, Specker SM, et al. (2008) Brain macrostructural and microstructural abnormalities in cocaine dependence. Drug Alcohol Depend 92: 164–172 doi:10.1016/j.drugalcdep.2007.07.019.

24.  Ersche KD, Barnes A, Jones PS, Morein-Zamir S, Robbins TW, et al. (2011) Abnormal structure of frontostriatal brain systems is associated with aspects of impulsivity and compulsivity in cocaine dependence. Brain 134: 2013–2024 doi:10.1093/brain/awr138.

25.  Ilg R, Wohlschlaeger AM, Gaser C, Liebau Y, Dauner R, et al. (2008) Gray matter increase induced by practice correlates with task-specific activation: A combined functional and morphometric magnetic resonance Imaging study. J Neurosci 28: 4210–4215 doi:10.1523/JNEUROSCI.5722-07.2008.