Samples

The sample sizes of the population-based studies varied significantly from 99 to 56 786 participants. Thirteen studies focused on adolescents, 17 on young adults (mostly university students), one on middle-aged adults only, and 7 on the entire adult lifespan.

Notably, 18 studies used at least partially overlapping data, which need to be considered when interpreting results. Specifically, Allen, Vella, & Laborde (Reference Allen, Vella and Laborde2015), Hakulinen and Jokela (Reference Hakulinen and Jokela2019), and Jokela, Airaksinen, Kivimäki, and Hakulinen (Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018) used data from the Household, Income, and Labour Dynamics Study (HILDA) in Australia. Jokela et al. (Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018), Hakulinen and Jokela (Reference Hakulinen and Jokela2019), Luchetti, Terracciano, Stephan, and Sutin (Reference Luchetti, Terracciano, Stephan and Sutin2018), and Stephan, Sutin, Luchetti, Caille, and Terracciano (Reference Stephan, Sutin, Luchetti, Caille and Terracciano2019) used data from the Health and Retirement Study (HRS) in the US. Jokela et al. (Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018) and Stephan et al. (Reference Stephan, Sutin, Luchetti, Caille and Terracciano2019) used data from the Midlife in Japan Study (MIDJA). Jokela et al. (Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018), Hakulinen and Jokela (Reference Hakulinen and Jokela2019), and Turiano, Whiteman, Hampson, Roberts, and Mroczek (Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012) used data from the Midlife in the US Study (MIDUS). Jokela et al. (Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018) and Hakulinen and Jokela (Reference Hakulinen and Jokela2019) used data from the German Socio-economic Panel (GSOEP). Jokela et al. (Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018), Hakulinen and Jokela (Reference Hakulinen and Jokela2019), and Stephan et al. (Reference Stephan, Sutin, Luchetti, Caille and Terracciano2019) used data from the Wisconsin Longitudinal Study (WLS) in the US. Blonigen et al. (Reference Blonigen, Durbin, Hicks, Johnson, McGue and Iacono2015), Hicks, Durbin, Blonigen, Iacono, and McGue (Reference Hicks, Durbin, Blonigen, Iacono and McGue2012), and Samek et al. (Reference Samek, Hicks, Durbin, Hinnant, Iacono and McGue2018) used data from the Minnesota Twin Family Study in the US. Quinn and Harden (Reference Quinn and Harden2013) and Wright and Jackson (Reference Wright and Jackson2022) used data from the National Longitudinal Study of Youth (NLSY) in the US. Littlefield, Sher, and Wood (Reference Littlefield, Sher and Wood2009), Littlefield, Sher, and Wood (Reference Littlefield, Sher and Wood2010b), Littlefield, Sher, and Steinley (Reference Littlefield, Sher and Steinley2010a), Littlefield and Sher (Reference Littlefield and Sher2012), and Littlefield, Vergés, Wood, and Sher (Reference Littlefield, Vergés, Wood and Sher2012) used data from the same student sample with similar time frames but considered different measures of impulsivity and extraversion. Kaiser, Bonsu, Charnigo, Milich, and Lynam (Reference Kaiser, Bonsu, Charnigo, Milich and Lynam2016) and Kaiser, Davis, Milich, Smith, and Charnigo (Reference Kaiser, Davis, Milich, Smith and Charnigo2018) used data from the same sample and measure of impulsivity; time frames were partly overlapping.

Study designs

In line with our search criteria, all studies were based on a longitudinal design, with number of waves ranging from 2 to 14 (median: 3 waves). The time span over which personality changes were assessed varied between 17 months and 30 years (median: 5 years). We present standardized effect sizes as exemplary but refrain from interpretations due to the large heterogeneity of studies.

Substances

In the observational studies, 31 studies investigated alcohol, 12 nicotine, 9 cannabis, and one ecstasy use. In addition, 4 studies investigated multiple drug use including cocaine and sedatives, and 2 examined SU in general without differentiation between different substances. Indicators of both SU and personality are described in online Supplementary Table S2.)

Extraversion-related traits (18 studies)

Seven of 15 studies reported at least one significant association between alcohol use and changes in extraversion (Hakulinen & Jokela, Reference Hakulinen and Jokela2019; Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Klimstra et al., Reference Klimstra, Luyckx, Hale and Goossens2014; Luchetti et al., Reference Luchetti, Terracciano, Stephan and Sutin2018; Östlund, Hensing, Sundh, & Spak, Reference Östlund, Hensing, Sundh and Spak2007), positive emotionality (Blonigen et al., Reference Blonigen, Durbin, Hicks, Johnson, McGue and Iacono2015), or sociability (Gmel, Marmet, Studer, & Wicki, Reference Gmel, Marmet, Studer and Wicki2020). However, these findings were inconsistent and varied, for example, by facet of extraversion (Östlund et al., Reference Östlund, Hensing, Sundh and Spak2007), measure, and cohort (Hakulinen & Jokela, Reference Hakulinen and Jokela2019). Eight studies in adults of different ages found no significant associations between alcohol use and extraversion-related changes using various SU(D) measures (Allen et al., Reference Allen, Vella and Laborde2015; Hicks et al., Reference Hicks, Durbin, Blonigen, Iacono and McGue2012; Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Littlefield et al., Reference Littlefield, Sher and Wood2009, Reference Littlefield, Sher and Wood2010b; Robert et al., Reference Robert, Luo, Yu, Chu, Ing, Jia and Schumann2020; Stein, Newcomb, & Bentler, Reference Stein, Newcomb and Bentler1987; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012).

For nicotine use, research found that initiation of smoking was linked to a small increase in extraversion (β = 0.07) (Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018) or that persistent smokers became less extraverted (d = 0.09–0.22) (Stephan et al., Reference Stephan, Sutin, Luchetti, Caille and Terracciano2019). Other studies found that nicotine use was unrelated to changes in extraversion (Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012) and positive emotionality (Welch & Poulton, Reference Welch and Poulton2009).

For cannabis and other drug use, one study found that higher cannabis use was associated with increases in extraversion in university students (Klimstra et al., Reference Klimstra, Luyckx, Hale and Goossens2014), while 2 studies found no significant links in adult samples (Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012). Taken together, the evidence on alcohol, nicotine, and other SU and changes in extraversion was inconsistent, with different directions of change, depending on age and personality measure.

Neuroticism-related traits (21 studies)

Eleven of 16 studies found that alcohol use was associated with increases in at least one neuroticism-related trait in samples of all ages (Allen et al., Reference Allen, Vella and Laborde2015; Blonigen et al., Reference Blonigen, Durbin, Hicks, Johnson, McGue and Iacono2015; Gmel et al., Reference Gmel, Marmet, Studer and Wicki2020; Hakulinen & Jokela, Reference Hakulinen and Jokela2019; Hicks et al., Reference Hicks, Durbin, Blonigen, Iacono and McGue2012; Littlefield et al., Reference Littlefield, Sher and Wood2009, Reference Littlefield, Sher and Wood2010b; Malmberg et al., Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013; Östlund et al., Reference Östlund, Hensing, Sundh and Spak2007; Samek et al., Reference Samek, Hicks, Durbin, Hinnant, Iacono and McGue2018; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012), although these findings were small (e.g. β = 0.04 in Allen et al., Reference Allen, Vella and Laborde2015) and varied by trait: Increased alcohol use was associated with increases in aggressive undercontrol but not negative emotionality in Samek et al. (Reference Samek, Hicks, Durbin, Hinnant, Iacono and McGue2018), increases in aggression hostility but not neuroticism-anxiety in Gmel at al. (2020), and increases in hopelessness but not anxiety sensitivity in Malmberg et al. (Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013). Five studies found no significant associations between alcohol use and neuroticism-related traits (Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Klimstra et al., Reference Klimstra, Luyckx, Hale and Goossens2014; Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Luchetti et al., Reference Luchetti, Terracciano, Stephan and Sutin2018; Robert et al., Reference Robert, Luo, Yu, Chu, Ing, Jia and Schumann2020).

Six of 10 studies found that nicotine use was linked to increases in neuroticism-related traits (Allen et al., Reference Allen, Vella and Laborde2015; Littlefield & Sher, Reference Littlefield and Sher2012; Malmberg et al., Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013; Mathijssen, Rozema, Hiemstra, Jansen, & van Oers, Reference Mathijssen, Rozema, Hiemstra, Jansen and van Oers2021; Stephan et al., Reference Stephan, Sutin, Luchetti, Caille and Terracciano2019; Welch & Poulton, Reference Welch and Poulton2009), although these effects were small (e.g. β = 0.07 for hopelessness in Malmberg et al., Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013) and often not consistent over the study period (e.g. Littlefield & Sher, Reference Littlefield and Sher2012; Malmberg et al., Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013). One study found a small decrease in neuroticism following smoking initiation (Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021), and 3 studies found no significant association between nicotine use and neuroticism (Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012) or hopelessness (Mathijssen et al., Reference Mathijssen, Rozema, Hiemstra, Jansen and van Oers2021).

For cannabis and other drugs, one study found that increasing sedative use was associated with subsequent increases in neuroticism (Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021), while 2 studies found no significant associations (Klimstra et al., Reference Klimstra, Luyckx, Hale and Goossens2014; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012). In sum, this indicates an association between higher alcohol use and increases in some neuroticism-related traits, while the evidence is less consistent for nicotine and other substances.

Openness-related traits (11 studies)

Four studies found associations between higher alcohol use and increases in openness (Klimstra et al., Reference Klimstra, Luyckx, Hale and Goossens2014; Robert et al., Reference Robert, Luo, Yu, Chu, Ing, Jia and Schumann2020; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012) or novelty seeking (Littlefield et al., Reference Littlefield, Vergés, Wood and Sher2012), mostly in young adults. In contrast, 5 studies (mostly based on adults of all ages) found no such associations (Allen et al., Reference Allen, Vella and Laborde2015; Hakulinen & Jokela, Reference Hakulinen and Jokela2019; Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Littlefield et al., Reference Littlefield, Sher and Wood2010b; Luchetti et al., Reference Luchetti, Terracciano, Stephan and Sutin2018).

For nicotine use, one study found that openness decreased among persistent smokers (Stephan et al., Reference Stephan, Sutin, Luchetti, Caille and Terracciano2019), while 4 studies found no significant association between nicotine use and change in openness (Allen et al., Reference Allen, Vella and Laborde2015; Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012). For cannabis and other drug use, one study found that higher cannabis was linked to increases in openness and its facet unconventionality in a college sample (Klimstra et al., Reference Klimstra, Luyckx, Hale and Goossens2014), while other research found no significant associations in adults (Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021). Overall, some evidence suggests that alcohol and cannabis use may be associated with increases in openness in adolescents and young adults.

Conscientiousness-related traits (16 studies)

Eight of 14 studies found that alcohol use was associated with decreases in conscientiousness-related traits (Blonigen et al., Reference Blonigen, Durbin, Hicks, Johnson, McGue and Iacono2015; Hakulinen & Jokela, Reference Hakulinen and Jokela2019; Hicks et al., Reference Hicks, Durbin, Blonigen, Iacono and McGue2012; Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Klimstra et al., Reference Klimstra, Luyckx, Hale and Goossens2014; Littlefield et al., Reference Littlefield, Sher and Wood2010b; Luchetti et al., Reference Luchetti, Terracciano, Stephan and Sutin2018; Samek et al., Reference Samek, Hicks, Durbin, Hinnant, Iacono and McGue2018), with small effect sizes (e.g. β = 0.09 in Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018). Six studies found no significant associations (Allen et al., Reference Allen, Vella and Laborde2015; Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Robert et al., Reference Robert, Luo, Yu, Chu, Ing, Jia and Schumann2020; Roberts & Bogg, Reference Roberts and Bogg2004; Stein et al., Reference Stein, Newcomb and Bentler1987; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012), potentially because they mostly relied on frequency measures of SU (rather than problematic SU).

Four studies found that nicotine use was associated with decreases in conscientiousness, mostly in young adults (Allen et al., Reference Allen, Vella and Laborde2015; Roberts & Bogg, Reference Roberts and Bogg2004; Stephan et al., Reference Stephan, Sutin, Luchetti, Caille and Terracciano2019; Welch & Poulton, Reference Welch and Poulton2009), while 4 studies found no significant associations in adults of all ages (Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Stein et al., Reference Stein, Newcomb and Bentler1987; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012). Roberts and Bogg (Reference Roberts and Bogg2004) found that cannabis use was associated with decreases in social responsibility in young women, while Kroencke et al. (Reference Kroencke, Kuper, Bleidorn and Denissen2021) found no significant associations in an older sample of both genders. There were no significant associations between other drug use and changes in conscientiousness-related traits (Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Stein et al., Reference Stein, Newcomb and Bentler1987; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012). In summary, there is some (albeit inconsistent) evidence that SU may relate to small decreases in conscientiousness.

Agreeableness-related traits (13 studies)

Three studies found that higher alcohol use was associated with decreases in agreeableness (Hakulinen & Jokela, Reference Hakulinen and Jokela2019; Klimstra et al., Reference Klimstra, Luyckx, Hale and Goossens2014; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012), and one study found that trait (non)conformity ‘normalized’ after remission from alcohol use disorder (Östlund et al., Reference Östlund, Hensing, Sundh and Spak2007). However, in 7 studies, alcohol use was unrelated to changes in agreeableness-related traits (Allen et al., Reference Allen, Vella and Laborde2015; Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Littlefield et al., Reference Littlefield, Sher and Wood2010b; Luchetti et al., Reference Luchetti, Terracciano, Stephan and Sutin2018; Robert et al., Reference Robert, Luo, Yu, Chu, Ing, Jia and Schumann2020; Stein et al., Reference Stein, Newcomb and Bentler1987).

Other drug (Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012) and nicotine (Allen et al., Reference Allen, Vella and Laborde2015) use were linked to decreases in agreeableness, and, conversely, smoking cessation to increases in agreeableness (Stephan et al., Reference Stephan, Sutin, Luchetti, Caille and Terracciano2019). In other studies, nicotine (Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Stein et al., Reference Stein, Newcomb and Bentler1987; Turiano et al., Reference Turiano, Whiteman, Hampson, Roberts and Mroczek2012) and cannabis (Klimstra et al., Reference Klimstra, Luyckx, Hale and Goossens2014; Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021) use were unrelated to changes in agreeableness. Taken together, a few studies suggest that SU(D) is associated with decreases in agreeableness-related traits, but this evidence is inconsistent.

Impulsivity-related traits (19 studies)

Ten of 10 studies found that alcohol use was associated with changes in impulsivity (Ashenhurst, Harden, Corbin, & Fromme, Reference Ashenhurst, Harden, Corbin and Fromme2015; Kaiser et al., Reference Kaiser, Bonsu, Charnigo, Milich and Lynam2016; Reference Kaiser, Davis, Milich, Smith and Charnigo2018; Littlefield et al., Reference Littlefield, Sher and Wood2009; Reference Littlefield, Sher and Steinley2010a; Malmberg et al., Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013; Quinn & Harden, Reference Quinn and Harden2013; Riley, Davis, Milich, & Smith, Reference Riley, Davis, Milich and Smith2018; White et al., Reference White, Marmorstein, Crews, Bates, Mun and Loeber2011; Wright & Jackson, Reference Wright and Jackson2022), and 6 of 6 studies (based on adolescent and young adult samples) found at least one association with changes in sensation seeking (Ashenhurst et al., Reference Ashenhurst, Harden, Corbin and Fromme2015; Kaiser et al., Reference Kaiser, Bonsu, Charnigo, Milich and Lynam2016; Kaiser et al., Reference Kaiser, Davis, Milich, Smith and Charnigo2018; Malmberg et al., Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013; Quinn & Harden, Reference Quinn and Harden2013; Wright & Jackson, Reference Wright and Jackson2022). The direction of change was almost exclusively positive and small to moderate in size. For instance, a within-person increase in drinking problems were linked to increases in multiple facets of impulsivity (e.g. lack of planning, β = 0.18–0.20) among college students (Riley et al., Reference Riley, Davis, Milich and Smith2018). However, some studies only found associations between individual waves (Littlefield et al., Reference Littlefield, Sher and Steinley2010a) or for specific SU measures (Malmberg et al., Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013).

Five of 5 studies found that nicotine use was associated with increases in impulsivity (Littlefield & Sher, Reference Littlefield and Sher2012; Malmberg et al., Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013; Mathijssen et al., Reference Mathijssen, Rozema, Hiemstra, Jansen and van Oers2021; Quinn & Harden, Reference Quinn and Harden2013; Wright & Jackson, Reference Wright and Jackson2022), and 3 of 4 studies found that nicotine use was associated with increases in sensation seeking (Malmberg et al., Reference Malmberg, Kleinjan, Overbeek, Vermulst, Lammers and Engels2013; Mathijssen et al., Reference Mathijssen, Rozema, Hiemstra, Jansen and van Oers2021; Wright & Jackson, Reference Wright and Jackson2022) in adolescents.

For cannabis use, Quinn and Harden (Reference Quinn and Harden2013) found increases in impulsivity but not sensation seeking from age 15 to 25, consistent with Wright and Jackson (Reference Wright and Jackson2022). De Win et al. (Reference De Win, Schilt, Reneman, Vervaeke, Jager, Dijkink and van den Brink2006) found that higher ecstasy use was linked to increases in sensation seeking but not impulsivity. Wright and Jackson (Reference Wright and Jackson2022) found that impulsivity and sensation seeking increased more strongly in adolescent cocaine users v. non-users. In summary, several studies suggest that SU relates to increases in impulsivity and sensation seeking, especially in adolescents and young adults.

Self-esteem and related traits (4 studies)

Stein et al. (Reference Stein, Newcomb and Bentler1987) found that alcohol use was associated with increases in one facet of self-esteem in women, while Kroencke et al. (Reference Kroencke, Kuper, Bleidorn and Denissen2021) and Wright and Jackson (Reference Wright and Jackson2022) found no such association. Wright and Jackson (Reference Wright and Jackson2022) found that self-esteem increased less consistently during adolescence in smokers v. non-smokers, whereas 2 studies found no significant association (Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021; Stein et al., Reference Stein, Newcomb and Bentler1987). Moreover, self-esteem increased less consistently in adolescent users (Wright & Jackson, Reference Wright and Jackson2022) and decreased in adult users (Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021) of sedatives/downers, whereas Stein et al. (Reference Stein, Newcomb and Bentler1987) reported increases in one facet of self-esteem in young adults, although not differentiating between types of drugs. Taken together, previous research suggests no consistent association between SU and changes in self-esteem.

Other (4 studies)

Other studies investigated traits such as identity status (De Moor, Sijtsema, Weller, & Klimstra, Reference De Moor, Sijtsema, Weller and Klimstra2022), cognitive structure (Labouvie & McGee, Reference Labouvie and McGee1986), autonomy (Labouvie & McGee, Reference Labouvie and McGee1986; Quinn, Stappenbeck, & Fromme, Reference Quinn, Stappenbeck and Fromme2011), or psychosocial maturity (Chassin et al., Reference Chassin, Dmitrieva, Modecki, Steinberg, Cauffman, Piquero and Losoya2010). For instance, in adolescent juvenile offenders, Chassin et al. (Reference Chassin, Dmitrieva, Modecki, Steinberg, Cauffman, Piquero and Losoya2010) found higher alcohol/cannabis use being associated with decreasing psychosocial maturity (β = −0.03/–0.05).

Directionality and within-person changes

Most observational studies investigating the directionality of change (online Supplementary Table S4) yielded bidirectional associations between SU and personality change. However, there was slightly more evidence for personality predicting subsequent changes in SU than for SU predicting subsequent personality changes. Studies that modeled between-person v. within-person effects evidenced within-person increases in impulsivity with higher/increasing SU (in college students) (Riley et al., Reference Riley, Davis, Milich and Smith2018) but found little evidence for associations between SU and within-person changes in the Big Five (Jokela et al., Reference Jokela, Airaksinen, Kivimäki and Hakulinen2018; Kroencke et al., Reference Kroencke, Kuper, Bleidorn and Denissen2021) (in adults of all ages).

Samples

Sample sizes in the intervention studies varied from 28 to 798. In contrast to the observational studies, the samples of the intervention studies mostly consisted of patients with (sub-)threshold SUD undergoing treatment. Only 3 studies examined non-clinical student samples (Kazemi, Levine, Dmochowski, Angbing, & Shou, Reference Kazemi, Levine, Dmochowski, Angbing and Shou2014; Winkleby, Feighery, Altman, Kole, & Tencati, Reference Winkleby, Feighery, Altman, Kole and Tencati2001, Reference Winkleby, Feighery, Dunn, Kole, Ahn and Killen2004).

Study designs

Assessment periods of the intervention studies ranged from four weeks to considerably longer timeframes up to 15 months post-intervention. Most studies were based on 3 or 4 waves and were conducted without control conditions. Only 4 studies used a randomized controlled design (RCT) (Bayır & Aylaz, Reference Bayır and Aylaz2021; Kayaoğlu & Şahin Altun, Reference Kayaoğlu and Şahin Altun2022; Nurco et al., Reference Nurco, Primm, Lerner, Stephenson, Brown and Ajuluchukwu1995; Winkleby et al., Reference Winkleby, Feighery, Altman, Kole and Tencati2001), one study used a randomized design (Stieger, Allemand, Roberts, & Davis, Reference Stieger, Allemand, Roberts and Davis2022), 2 studies used a non-randomized control-group design (Can Gür & Okanli, Reference Can Gür and Okanli2019; Gonçalves et al., Reference Gonçalves, Ometto, Bechara, Malbergier, Amaral, Nicastri and Cunha2014), and one study used matched control groups (Oei & Jackson, Reference Oei and Jackson1980).

Substances

Of the 17 intervention studies, 4 focused on alcohol use, one focused on nicotine use, one focused on heavy use of opioids, cocaine, and heroin, respectively, and nine were intervention studies that focused on treatment programs for heavy SU of various kinds and did not test for substance-specific effects. Indicators of SU(D) and personality that were considered in these studies are described in online Supplementary Table S2.

Interventions

The studies encompassed various treatments, such as individual- and group-based cognitive-behavioral therapy and 12-step facilitation approaches to recovery (adapted from Alcoholics/Narcotics Anonymous) (Aklin, Tull, Kahler, & Lejuez, Reference Aklin, Tull, Kahler and Lejuez2009; Blonigen & Macia, Reference Blonigen and Macia2021; Can Gür & Okanli, Reference Can Gür and Okanli2019; Chodkiewicz & Gruszczyńska, Reference Chodkiewicz and Gruszczyńska2019; Kayaoğlu & Şahin Altun, Reference Kayaoğlu and Şahin Altun2022; Littlefield et al., Reference Littlefield, Stevens, Cunningham, Jones, King, Schumacher and Coffey2015; Stieger et al., Reference Stieger, Allemand, Roberts and Davis2022), motivational interventions (Gonçalves et al., Reference Gonçalves, Ometto, Bechara, Malbergier, Amaral, Nicastri and Cunha2014; Kazemi et al., Reference Kazemi, Levine, Dmochowski, Angbing and Shou2014), mindfulness-based interventions (Bayır & Aylaz, Reference Bayır and Aylaz2021; Stieger et al., Reference Stieger, Allemand, Roberts and Davis2022), but also less usual interventions such as motivational chess (Gonçalves et al., Reference Gonçalves, Ometto, Bechara, Malbergier, Amaral, Nicastri and Cunha2014), music (Kayaoğlu & Şahin Altun, Reference Kayaoğlu and Şahin Altun2022), or advocacy training for students (Winkleby et al., Reference Winkleby, Feighery, Altman, Kole and Tencati2001; Reference Winkleby, Feighery, Dunn, Kole, Ahn and Killen2004). Durations of the interventions ranged from 4 to 25 weeks.

Extraversion-related traits (6 studies)

Two studies found that extraversion increased from admission to 19-week follow-up in patients from an opioid treatment clinic using agonist medication and behavioral interventions (Carter et al., Reference Carter, Herbst, Stoller, van King, Kidorf, Costa and Brooner2001) and from pre-treatment to 12-month follow-up in patients from a residential alcohol treatment program using social skills training and supportive therapy (Oei & Jackson, Reference Oei and Jackson1980).

Three studies found that extraversion increased in SUD patients receiving cognitive behavioral therapy (CBT) and other multimodal interventions only from pre- to post-treatment, but not until 6-month (Stieger et al., Reference Stieger, Allemand, Roberts and Davis2022), 12-month (Blonigen & Macia, Reference Blonigen and Macia2021), or 15-month follow-up (Piedmont, Reference Piedmont2001). One study found no changes in extraversion in relation to SUD treatment (Borman et al., Reference Borman, Zilberman, Tavares, Surís, El-Guebaly and Foster2006). In summary, there is some evidence for increases in extraversion in SUD patients during treatment that, however, are not sustained in the long term.

Neuroticism-related traits (6 studies)

All studies found decreases in neuroticism-related traits in relation to different SU(D) interventions (e.g. CBT, motivation intervention program, social skills training) and settings (e.g. outpatient (Carter et al., Reference Carter, Herbst, Stoller, van King, Kidorf, Costa and Brooner2001; Piedmont, Reference Piedmont2001), inpatient (Blonigen & Macia, Reference Blonigen and Macia2021; Borman et al., Reference Borman, Zilberman, Tavares, Surís, El-Guebaly and Foster2006; Oei & Jackson, Reference Oei and Jackson1980), university (Kazemi et al., Reference Kazemi, Levine, Dmochowski, Angbing and Shou2014)). Lower levels of neuroticism-related traits were maintained up to 15 months post-treatment (d = 0.28 mean Big Five change) (Piedmont, Reference Piedmont2001). Social skills training was associated with greater decreases in neuroticism than supportive therapy in alcohol use patients (Oei & Jackson, Reference Oei and Jackson1980). Taken together, the evidence suggests that SU(D) interventions are associated with sustained reductions in neuroticism.

Openness-related traits (4 studies)

Two studies found increases in openness-related traits in SUD patients from pre- to post-treatment (i.e. CBT and comprehensive multimodal interventions) that, however, were not maintained until 6-month (Stieger et al., Reference Stieger, Allemand, Roberts and Davis2022) and 15-month (Piedmont, Reference Piedmont2001) follow-up. Conversely, no changes in openness-related traits were found in relation to multimodal (Borman et al., Reference Borman, Zilberman, Tavares, Surís, El-Guebaly and Foster2006) and opioid (Carter et al., Reference Carter, Herbst, Stoller, van King, Kidorf, Costa and Brooner2001) treatment. Thus, previous evidence suggests no lasting changes in openness-related traits following SUD treatment.

Conscientiousness-related traits (5 studies)

Four studies found lasting increases (up to 15-month follow-up) in conscientiousness (Carter et al., Reference Carter, Herbst, Stoller, van King, Kidorf, Costa and Brooner2001; Piedmont, Reference Piedmont2001; Stieger et al., Reference Stieger, Allemand, Roberts and Davis2022) and constraint (Blonigen & Macia, Reference Blonigen and Macia2021) in relation to (cognitive) behavioral approaches (e.g. d = 0.37 from pre- to post-treatment in Stieger et al., Reference Stieger, Allemand, Roberts and Davis2022). In contrast, Borman et al. (Reference Borman, Zilberman, Tavares, Surís, El-Guebaly and Foster2006) found no significant changes in conscientiousness and persistence but increases in self-directedness from admission to 6-month follow-up in an intervention focusing on physical, emotional, social, and spiritual factors. Taken together, there is initial evidence that cognitive-behavioral SUD treatment relates to increases in conscientiousness-related traits.

Agreeableness-related traits (4 studies)

One study found increases in agreeableness in SUD patients up to 6-month follow-up (Piedmont, Reference Piedmont2001), another found increases from pre- to post-treatment, but this effect disappeared at 6-month follow-up (Stieger et al., Reference Stieger, Allemand, Roberts and Davis2022). Two studies found no significant changes in agreeableness-related traits related to SUD treatment (Borman et al., Reference Borman, Zilberman, Tavares, Surís, El-Guebaly and Foster2006; Carter et al., Reference Carter, Herbst, Stoller, van King, Kidorf, Costa and Brooner2001). The evidence provides little support for lasting increases in agreeableness following SUD treatment.

Impulsivity-related traits (4 studies)

Kazemi et al. (Reference Kazemi, Levine, Dmochowski, Angbing and Shou2014) found a decrease in impulsivity among university students who participated in an alcohol intervention to motivate change in drinking behavior (either mandated or voluntarily) from baseline to 6-month follow-up, including booster sessions. In inpatient multimodal SU treatments, Littlefield et al. (Reference Littlefield, Stevens, Cunningham, Jones, King, Schumacher and Coffey2015) found decreases in some facets of impulsivity, while Aklin et al. (Reference Aklin, Tull, Kahler and Lejuez2009) found no significant changes in impulsivity but decreases in risk taking, both after 4 weeks of intervention. Gonçalves et al. (Reference Gonçalves, Ometto, Bechara, Malbergier, Amaral, Nicastri and Cunha2014) found no changes in impulsivity following a 4-week motivational interviewing and chess intervention for cocaine users in a psychiatric clinic. For sensation seeking, no significant changes in relation to SUD treatment were found (Kazemi et al., Reference Kazemi, Levine, Dmochowski, Angbing and Shou2014; Littlefield et al., Reference Littlefield, Stevens, Cunningham, Jones, King, Schumacher and Coffey2015). These results provide some, but inconsistent evidence for decreases in impulsivity-related traits in relation to SU(D) interventions.

Self-efficacy and related traits (7 studies)

Only studies that focus on general (but not domain-specific) self-efficacy are considered, as the focus of this review is on major personality traits. RCTs in SUD patients found that clinically guided self-help plus standard treatment (i.e. methadone maintenance and counselling) (Nurco et al., Reference Nurco, Primm, Lerner, Stephenson, Brown and Ajuluchukwu1995), mindfulness-based psychoeducation (Bayır & Aylaz, Reference Bayır and Aylaz2021), CBT with music intervention (Kayaoğlu & Şahin Altun, Reference Kayaoğlu and Şahin Altun2022), and advocacy training to reduce smoking in university students (Winkleby et al., Reference Winkleby, Feighery, Dunn, Kole, Ahn and Killen2004) led to increases in self-efficacy (or changes from external to internal locus of control, Nurco et al., Reference Nurco, Primm, Lerner, Stephenson, Brown and Ajuluchukwu1995). Two studies without a randomized controlled design also found that self-efficacy increased in university students following an advocacy intervention to reduce smoking (Winkleby et al., Reference Winkleby, Feighery, Altman, Kole and Tencati2001) and in alcohol use patients from pre- to post-treatment (i.e. CBT plus exercise incentives) but not to 4- or 6-month follow-up (Can Gür & Okanli, Reference Can Gür and Okanli2019). One study found no changes in self-efficacy after 6-week CBT (Chodkiewicz & Gruszczyńska, Reference Chodkiewicz and Gruszczyńska2019). Taken together, these findings suggest that most SU(D) interventions increase self-efficacy.

Other (3 studies)

Other personality-like traits investigated in the context of SU(D) interventions were reward dependence (Borman et al., Reference Borman, Zilberman, Tavares, Surís, El-Guebaly and Foster2006), psychoticism (Oei & Jackson, Reference Oei and Jackson1980), or resilience (Stieger et al., Reference Stieger, Allemand, Roberts and Davis2022). For instance, Stieger et al. (Reference Stieger, Allemand, Roberts and Davis2022) found that SUD patients exhibited increases in trait resilience up to 6 months after CBT.