| Substance use disorder(SUD)refers to a cluster of addictive disorders due to continuous use of psychoactive drugs or substances,such as tobacco,alcohol,marijuana and opioids.The basic characteristics of SUD comprise cognitive,behavioral,and physical symptoms.Besides,individuals with substance use disorders continue to use drugs despite significant substance related problems.Although the specific categories of SUD differ from each other,they do have in common that if they are overtaken,all of these substances directly or indirectly activate the brain's reward system.As a result,individuals who abuse drugs often neglect normal activities and spend a lot of time,energy or money on drug use.By contrast,many behaviors such as gambling and online gaming do not involve the ingestion of psychoactive substances,but they can still activate the reward system similar to substance use disorders,leading to clinical symptoms that could be similarly seen in substance use disorders.However,there is not enough research focused on the mechanisms of behavioral addiction nowadays.More importantly,no definite and effective treatments for severe SUD and behavioral addictions are proposed.Thus,early identification and intervention are the key to the prevention and treatment of different addictive behaviors.Recently,impulsivity has been shown to be a risk factor for the initiate and development of substance use disorders.Given the fact that adolescence and early adulthood are usually the core periods when SUD begins and impulsive behavior increases,it is very important to study the relationships between impulsivity and SUD in young people.Although impulsivity might be an important target for early identification and intervention of addictive behaviors,this view is still inconclusive because of the limitations and flaws of current studies.In particular,most of the existing research results are based on SUDs,but lack of prospective designs,cross-spectrum comparisons and other data.It is believed that the occurrence and development of substance use disorders are influenced by both individual susceptibility and biochemical effects of substances,so the nature of neurocognitive abnormalities of the addicted individuals(e.g.,high impulsivity,decreased behavior inhibition,compromised functions of the brain system)is quite difficult to explain: are these abnormalities a predisposition of individuals,or are they the result of chronic damage to brain structure and function caused by drugs?By comparison,behavioral addictions do not involve the toxic effects of substances and effectively eliminate the interference of drug abuse,therefore they provide an ideal model for studying the basic or primordial susceptibility mechanisms of addictive disorders.In addition,definitions and measurements of impulsivity have varied greatly from one study to another study(e.g.,some studies just share no more than 5% of the common variance),but a large body of literature labels these different impulsive structures as identical,leading to quite different results that cannot be compared and explained directly.Based on these above-mentioned important questions,the present study comprehensively adopted self-reports,experimental methods,event-related potentials(ERP)and other methods,and compared the characteristics of impulsivity between SUD and behavioral addiction,including trait impulsivity,behavioral impulsivity,and physiological or neural correlates of impulsivity.The purpose of this study was to explore the similarities and differences of impulsivity between SUD and behavioral addiction,as well as the neurobiological basis of impulsivity,through a cross-spectrum comparison design of different addictions.There were four sub-studies:(1)Study 1 is the revision of research tools.Items Analysis,Exploratory Factor Analysis,Rasch Model Analysis,and Confirmatory Factor Analysis were used to revise the BIS-11 and UPPSP,the two most widely used questionnaires for trait impulsivity at present.After the four stages of revision,the final forms of each tool(i.e.,BIS-11,UPPSP)are finally obtained for subsequent research;(2)Study 2 used the revised BIS-11 and UPPSP scales to directly compared the impulsive characteristics of problem smoking behavior and problem Internet use among Chinese college students,simultaneously including two independent samples over three years to examine the consistency of smoking behavior,problem Internet use and impulsivity;(3)Study 3 adopted the Delay Discounting Task(DDT),the Stop Signal Task,and the Stroop Task,and compared the commonality and specificity of impulsive decision-making and impulse inhibition between disordered tobacco users and Internet addicts;and(4)Study 4 employed the electrophysiological technology of event-related potentials(ERP)to compare the impairments of impulsive control and the related neurophysiological bases in disordered tobacco users and Internet addicts.The main findings of this study are as follows:(1)SUD and behavioral addiction share some common patterns of trait impulsivity,such as that Internet addiction and problem smoking behavior have similar high level of attentional impulsiveness,but both behaviors also have specific characteristics of impulsivity that lack of perseverance,non-planning impulsiveness,and negative urgency(impulsivity under negative emotions)predicted Internet addiction,while sensation seeking predicted problem smoking behavior;(2)In terms of the inhibition of impulsive behavior,SUD and behavioral addiction exhibit an evident spectral separation model.For one thing,disordered tobacco users showed significant impairments on cognitive inhibition function(i.e.,dominant mental representation),which might attribute to the toxic effects of the long-term use of nicotine,while Internet addicts did not have significant impairments of cognitive inhibition.For another thing,On the specific function of impulse response inhibition(i.e.,the dominant response inhibition function)closely related to the control of addictions,both disordered tobacco users and Internet addicts showed the similar characteristics of impaired impulse control functions.This might account for their inability to control the cravings for cigarettes or Internet use;and(3)the ERP data revealed that during the impulse response inhibition,the amplitudes of P300 of Internet addicts and disordered tobacco users were significantly lower than that in healthy controls,displaying the similar abnormalities of cognitive electrical activity between the two groups.Meanwhile,diffuse electrical activity abnormalities(e.g.,higher latency of N200 and P300,lower amplitudes of N450 and P300)were observed in disordered tobacco users,representing the potential neurophysiological mechanisms of cognitive conflict monitoring and processing dysfunction.To sum up,this study initially revealed the common and specific characteristics of impulsivity as well as the neurophysiological bases in substance use disorder(i.e.,problem tobacco use)and behavioral addiction(i.e.,problem Internet use).Nevertheless,the nature of this study design was a cross-sectional investigation essentially,thus it was not able to determine causal relationships,and it is necessary to conduct longitudinal studies in the future.Besides,the study samples consisted of young college students mostly,so these findings could not be generalized to the other populations(e.g.,community samples,treatment-seeking samples),or to the other age groups(e.g.,middle and late adulthood). |
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