Association between Cannabis use, Depression and Apathy: A Study of an Internet Community Sample of Young Adults

The trait of amotivation is commonly clinically described among chronic cannabis abusers but few empirical studies have provided data on this dimension. Thus, our objective was to determine to what extent apathy, evaluated in a multidimensional approach, is associated with cannabis use and misuse in a community sample of young adults. 677 participants with a mean age of 20.5 years completed several web-formatted self-reports including the Lille Apathy Rating Scale (LARS) adapted to a self-report format (LARS-SR) and the 13-item Beck Depression Inventory (BDI-13). Participants were asked about their use of cannabis and, if appropriate, the Cannabis Abuse Screening Test (CAST) was completed. The problematic CU according to the CAST presented higher scores on the LARS-SR total score, LARS-SR subscales “intellectual curiosity”, “emotion”, and “action initiation” and the BDI-13 in comparison with non-problematic users. Regression analyses revealed that both apathy and depression were signifi cant predictors of the CAST categories (non-symptomatic vs. moderate/severe). Despite some limitations, our study about the impairment of motivational functioning provides some new insight into the clinical implications of problematic patterns of cannabis use. Indeed, apathy was associated with both cannabis use and more severe patterns of cannabis use as evaluated with the CAST. The use of a scale investigating apathy as a multidimensional construct reveals that only some apathy dimensions seem involved in cannabis misuse independently of depression. Research Article Association between Cannabis use, Depression and Apathy: A Study of an Internet Community Sample of Young Adults Géraldine Dorard* and Manon Cebron De Lisle Laboratory of Psychopathology and Health Process EA 4057, University Institute Paris Descartes of Psychology, Paris Descartes University, Sorbonne Paris Cité, 71 avenue Édouard Vaillant, 92100 Boulogne-Billancourt, France Dates: Received: 14 February, 2017; Accepted: 20 March, 2017; Published: 21 March, 2017 *Corresponding author: Géraldine Dorard, Laboratoire de Psychopathologie et Processus de Santé (EA 4057), IUPDP, Université Paris Descartes, Sorbonne Paris Cité, Institut Henri Piéron, 71 avenue Édouard Vaillant, 92100 Boulogne-Billancourt, France, Tel: 843792 2322; Fax: 0033 (1)76 53 29 62; E-mail:


Introduction
Today, the use of illicit substances among adolescents and young adults is a major public health concern. Cannabis is the illegal substance most commonly abused by French young people [1]. This high prevalence of consumers is refl ected in the large number of specialized care demands motivated by problematic cannabis use, even if in most cases this use is recreational [2]. While dependence occurs in approximately 9% of users [3], problems associated with cannabis use may arise before addiction appears. Some patterns of use (e.g., use before midday, solitary use) have been consistently associated with adverse effects and in order to detect this problematic use in the general population, a standardized and sensitive scale has been developed and widely validated: the Cannabis Abuse Screening Test [4][5][6].
The evaluation of affective style and emotional functioning has become an important topic in the process of understanding the underlying mechanisms of substance use disorders [7][8][9][10]. The association between substance use and affective pathology, such as depressive and anxiety states, has been well demonstrated during adolescence and adulthood [11][12][13][14][15].
Beyond depression, since the early 1970s, the traits of passivity or amotivation have commonly been clinically described among chronic cannabis abusers. The term "amotivational syndrome" was proposed to describe decreased motivation, reduced ability to concentrate, loss of effectiveness, decreased capacity to carry out complex plans or prepare realistically for the future [16]. Some researchers suggest that this amotivational state could be linked to the biological action of cannabis on the brain, in particular dopamine synthesis. These brain effects could be sustained by the increasing concentration of THC consistently reported [17]. Although clinically well recognized, the syndrome is questioned in the empirical literature [16]. However, the numerous psychosocial correlates (i.e., poor school achievement, cognitive impairments) regularly associated with heavy cannabis use confi rm the need to clarify it [17,18]. One way to study this non-consensual complex multidimensional entity is to investigate apathy, which appears to be a key component of the amotivational syndrome. Apathy is defi ned as a multidimensional psychopathological state affecting cognitive, behavioral (sensory and motor) and emotional functioning, conceptualized as reduced motivation corresponding to goal-directed behaviors [19]. Descriptions of the syndrome are quite heterogeneous, however there is a relative consensus that it is mostly characterized by a reduced interest in and a diminution of everyday life activities, a lack of initiative and interest, a trend to quit initiated action prematurely (lack of perseverance in voluntary action), indifference and a fl attening of affect [19,20].  [21][22][23], although empirical studies favored a dimensional approach to apathy. Apathy is associated with a quantitative reduction in adaptive behaviors.
Despite their overlapping constructs, depression and apathy should be considered separate dimensions, as they can both co-occur and standalone [19,24,25]. Apathy is a motivational disorder whereas depression is an affective one and some studies, using validated apathy scales, have shown that apathy is a clinically distinct syndrome warranting specifi c treatment interventions [26]. However, because the two constructs share several common symptoms (e.g., fatigue, loss of pleasure, reduced concentration), they could easily be confused in a clinical setting without standardized evaluations [19], particularly in cannabis abusers who often have diffi culty in identifying or expressing feelings [8,12,27]. Moreover, some suggest that the two dimensions could have a cumulative effect on the expression of symptoms [28].
In their construction, apathy measures were not designed as a geriatric rating scale and should be suitable for adolescent and adult populations with various clinical disorders [19]. However, only a few studies have investigated apathy in other conditions than neurological or schizophrenia and depression. Yet, even before the concept was studied in these pathologies, Meerloo questioned its role in TV addiction as early as 1962 [29]. System Behavior Scale (FrSBe); see [24], two studies reported more apathy in cocaine-dependent subjects than in non-drugusing controls [36,37]. Another study revealed that apathy was associated with the intensity of the hedonic response during cocaine intake, but was independent of the craving response [38]. Looby and Earlywine [39], highlighted more apathy in methamphetamine users; a paradoxical effect considering the stimulant properties of the substance.
The relative scarcity and heterogeneity of the literature highlight the need for a better understanding of the link between apathy and substance use, cannabis in particular.
Moreover, because patterns of cannabis use differ between adolescents and adults (i.e., use before midday and intensity of smoking more frequent in young than in older adults), specifi c studies in samples of young adults are needed [4].
Thus, our objective was to determine to what extent apathy, evaluated in a multidimensional approach, is associated with cannabis use and misuse in a community sample of young adults. We hypothesized that the current cannabis users would have higher mean levels of depression and apathy than the non-users (not current users and never users), and that apathy would be associated with the problematic use of cannabis independently of depression.

Materials
Participants completed several self-reports including: An ad-hoc socio-demographic questionnaire: in addition to classic data (age, gender, level of education, professional activity), several precise but easily understandable questions were formulated in order to assess the exclusion criteria (listed above).
The Lille Apathy Rating Scale (LARS) [20,40], adapted to a self-report format for this study (LARS-SR). In its original format, the LARS is a 33-item apathy scale administered The self-report format of the LARS (LARS-SR) has only 31 items, as the two items evaluating reaction time were not adaptable for self-report and were removed. As in the original version, participants were fi rst asked to report their standard day-to-day activities, which were coded on a fi ve-point Likerttype scale (ranging from -2 to 2) according to their number and diversity. Then participants had to report their areas of interest. These answers were coded with two items: the fi rst was about the number of pastime (1: none or just one; 0: many; -1: plenty) and the second concerned their frequency (1: less than once a week; 0: once or many times a week; -1: no enough time for pastime activities). Afterward, participants responded to the remaining 28 items, having a binary responses format (true: 1 or false: -1) as in the original version. The binary (yes/ no) scale allows a self-reported adaptation since the "yes"or-"no" format reduces subjective interpretations as much as possible. Thus, the LARS-SR comprises 31 items and the overall score ranges from -32 (best possible score -no apathy) to +32 (worst possible score -severe apathy). The LARS has been validated in Parkinson's disease [20] and schizophrenia [41] and a caregiver version has been developed [40]. The scale also exhibited good psychometric properties in the healthy control group sample [20,41]. and problems linked to cannabis use. All items are answered on a fi ve-point scale (0 "never", 1 "rarely", 2 "from time to time", 3 "quite often", 4 "very often"). The total score ranged from 0 to 24. Empirical cut-off points for the CAST, ordering individuals along a continuum of problems, have been determined: non-symptomatic (score ≤ 2), moderate (score from 3 to 6) and severe (score ≥7). Its psychometric properties have been assessed in representative samples of adolescents and in small samples of young adults in various European countries [4]. Secondly, in order to test the effect of the severity of problematic cannabis use, the sample of Current Cannabis Users (C-CU) was separated into two groups according to their results on the CAST: the non-symptomatic versus the moderate and severe problematic users. Then, independentsample t-tests were calculated to determine the differences in dimensional measures. In addition to this two-group approach, ANOVA with Tukey post-hoc analyses were calculated in order to compare the distribution of the exhibited effects between the non-symptomatic, moderate and severe CAST categories.

Data management and statistical analysis
Next, several models of multivariate logistic regression analyses were designed with the CAST group (non-symptomatic vs. moderate or severe problematic users) as the dependent variable, the LARS-SR total score and subscale scores as predictors, and the BDI-13 score as a systematic covariable.
Separate models were calculated for each of the four LARS-SR subscales.
Finally, six distinct models of multivariate logistic regression analyses were designed with the 6 items of the CAST as the dependent variable, the LARS-SR total score as predictor, and the BDI-13 score as a systematic covariable.
All analyses were carried out with SPSS-24 and hypotheses were tested with a two-sided signifi cance level of 0.05.

Results
The fi nal sample comprised 677 participants (291 males -386 females) with a mean age of 20.5 (SD=1.9) ranging from 18 to 25 years. The socio-demographic and psychometric characteristics of the participants are described in Table 1.
The correlation between the LARS-SR and the BDI-13 was signifi cant and moderate (r=.312, p<.001).

Comparison between current (C-CU), not current (NC-CU) and never (N-CU) cannabis users
The ANOVAs highlighted some overall effects of the groups for age, the LARS-SR total score and the emotion subscale (Table 1).
The post-hoc analyses revealed that the participants that had experience of cannabis in their lifetime but had not used it during the previous year (NC-CU) were older (mean difference=.546; p=008) and more apathetic (mean difference =-1.42, p=.032), notably on the emotion subscale of the LARS-SR (mean difference =.473, p=.001) than the participants who had never tried cannabis (N-CU).
Then, there was no signifi cant difference between the mean age of the fi rst cannabis use of the C-CU (mean age (SD) = 15.9 (1.8)) and the NC-CU (mean age (SD) =16.3 (1.9)) participants (F=2.22, p=.137).

Determination of problematic cannabis use for the current users
The CAST mean score in the subsample of participants who reported current cannabis use (n=225) was 3.5 (SD=4.2); scores ranged from 0 to 19.

Differences between non-symptomatic and problematic cannabis users
Descriptive and comparative statistics between non- symptomatic and problematic cannabis users on the CAST are presented in Table 2.
Participants presenting a moderate or severe problematic cannabis use had a higher LARS-SR total score (p=.001). This signifi cant intergroup difference was also found for the LARS-SR subscales "intellectual curiosity" (p=.020), "emotion" (p=.009) and "action initiation" (p=.003). Moreover, they had a signifi cantly higher score on the BDI-13 (p<.0001).
The ANOVA exploring the differences between the three categories of the CAST (non-symptomatic, moderate and severe) revealed that severe users were more apathetic than non-symptomatic users on the LARS-SR (mean difference=-3.6, p=.001) and the action initiation subscale (mean difference=-.63, p=001).
No signifi cant differences were highlighted between moderate users and both non-symptomatic and severe users regarding the LARS-SR scores, but a signifi cant effect was found for the BDI-13 scores between moderate and severe categories (mean difference=-2.8, p=.022).

Multivariate logistic regression analyses
Regression analyses revealed that both apathy and depression scores were signifi cant predictors of the CAST categories (non-symptomatic vs. moderate/severe) (=1.07, p=.010 and =1.08, p=.008, respectively).
In order to determine precisely which of the behavioral issues investigated in the CAST questionnaire were predicted by apathy, multivariate logistic regression analyses were performed with each CAST item as a dependent variable and LARS-SR and BDI-13 as predictors.
Analyses revealed that solitary cannabis use (item 2) was signifi cantly predicted by the LARS-SR total score (=1.062, p=.012) as were items investigating problems related to cannabis use (item 6) (=1.062, p=.022). On the other hand, the item "tried to reduce or stop" was predicted by the BDI-13 score (=1.079, p=.020) ( Table 3).

Discussion
One of the main original features of our research was the transposition of the apathy concept, classically studied in neuropsychiatric disorders, to a young community sample, linked with an addictive behavior studied from a behavioral and psychopathological perspective. Considering the amotivational syndrome frequently described in the clinical presentation of cannabis abusers, we believe that the study of apathy may bring some insight into the understanding of this problematic behavior, widespread among young people. Moreover, whereas there is an extensive literature investigating the links between depression and cannabis use and misuse, few studies have investigated apathy in substance use disorders. Some have revealed specifi cities in cannabis-dependent and cocaine and methamphetamine abusers, who were found more apathetic than controls [33,36,37,39]. Others failed to demonstrate signifi cant differences between substance abusers and controls [31,35]. However, our study is the fi rst to investigate the presence of apathy in problematic cannabis users using a validated scale, in comparison to non-symptomatic users in a community sample of young adults.
Since our results, once again, confi rmed the strong association between problematic cannabis use and depressive symptomatology in a community sample of non-clinical participants [44], regression analyses were calculated in order to determine the discriminability of apathy and depression.
As predicted, both depression and apathy total scores were consistently associated with problematic patterns of cannabis use. One of the strengths of our study is also the use of a scale investigating apathy as a multidimensional construct, and revealing that only some apathy dimensions seem involved in cannabis misuse independently of depression: emotion and action initiation. Interestingly, whereas some research has demonstrated some diffi culties in self-perception, notably a lack of insight regarding emotional states e.g., alexithymia, [12,27], no signifi cant associations were revealed concerning the self-awareness apathy subscale.
Volkow, et al. concluded their review by stating that further studies are needed to determine whether the defi cits in motivation are linked to cannabis use disorders rather than cannabis use per se [17]. Our study provides some insight regarding this point since apathy was associated with both cannabis use and problematic patterns of cannabis use. However, the strongest associations were found with the cannabis-related social, cognitive, behavioral and physiological problems. In order to understand better the contribution of the pathological dimension associated with the substance use behavior, it would be helpful to reproduce our study using the new DSM-5 criteria for problematic use of cannabis [45].
Early cannabis initiation was associated with a more severe problematic pattern of cannabis use. This result once again underlines the need to delay the initiation of cannabis use in order to prevent the development of cannabis-related problems such as low educational attainment or poor psychosocial adjustment [14].
In terms of representability, our sample was deliberately chosen in an age range of young adults who tend to exhibit a specifi c pattern of substance use [4] and it allowed a certain homogeneity of the cannabis use patterns. Moreover, as previously reported, the level of current cannabis users was higher in males, which is a classic gender difference, although this heterogeneity tends to disappear when problematic use is considered [1,46]. However, a major limitation resides in the sample of participants. Overall, 1431 participants connected to the platform and gave their informed consent but 686 were excluded because of incomplete data (48% of the initial respondents). One can question the lack of motivation and perseverance in completing all the questionnaires, which may mean that the most apathetic or depressed participants were de facto not included in the analyzed sample.
Nevertheless, this recruitment method presents some advantages since participants should be sincerer in a completely anonymous and depersonalized procedure. Previous studies demonstrated this effect since young participants were found more likely to admit to substance use in a web-based questionnaire than on a paper-and-pencil questionnaire [47,48]. Moreover, we may hypothesize that the electronic format favors completion because of the easy access (adapted format for Smartphones) and enables the inclusion of young adults who are part of a highly connected generation.
One of the measurement limitations resides in the adaptation of the apathy measure to a self-report format in a young community sample, which led to the removal of the reaction time items. The impact of the adaptation is limited by the exclusive multidimensional approach in our study; however, taking into account the relevance of the concept, we consider that further studies exploring the psychometric validated version are needed in participants with effi cient cognitive functioning. Moreover, as in a clinical setting, a shortened version should be encouraged [49].
We chose to study the dimensions of depression and apathy only in a psychometric psychopathological perspective.
However, considering the empirical literature on cannabis and brain development or damage and the neurobiological evidence about apathy, multidisciplinary research linking both psychometric and biophysiological measures should be encouraged in the future. Taking into account the links between cannabis and psychosis on one hand [17], and between schizophrenia and apathy on the other [41], our study linking cannabis misuse and apathy in young adults raises some questions about potential mediating effects between these dimensions. In addition, a longitudinal assessment of individuals would have enabled us to determine the durability of these effects and/or whether the depressive and apathy syndromes are pre-existent to substance use. Such a design is needed and our results need to be replicated in a clinical setting and not only in a general population Whatsoever, this work provides an additional view of what studying apathy could contribute to research on addiction.