These results indicate that METH may not only hinder brain development and The present study examined how differences in the stress response related to substance use in a sample of Mexican-origin youth growing up in a low-income region with high levels of adversity . Using a longitudinal study design, we tested whether differences in HPA axis reactivity and emotion and recovery to stress at age 14 were associated with use of alcohol, marijuana, and cigarette use by age 14 ; use of alcohol, marijuana, cigarettes, and vaping of nicotine by age 16; and onset of alcohol, marijuana, and cigarette use between ages 14 and 16. Finally, we tested whether associations between stress reactivity, stress, recovery, and substance use varied by poverty status and sex. Substance use greatly increases during adolescence, as the percentage of students who have used an illicit drug doubles from 8th to 10th grade, and nearly half of students report using at least one substance by 12th grade . Although experimentation is common in adolescence, youth who use alcohol, tobacco, and marijuana earlier in adolescence are at higher risk for psychopathology and substance use disorders in adulthood . Previous research has also consistently found that use of alcohol and marijuana by ages 14 and 16 specifically are related to poorer adjustment and higher use later in adolescence and adulthood . Risk is particularly high for Latinx adolescents, who show higher lifetime use of varied substances by 8th grade and by 12th grade compared to White and Black youth, and tend to begin using cigarettes, alcohol, and other drugs at earlier ages than other ethnic minorities . Furthermore, prior research suggests that Mexican American adolescents, specifically, are more likely to have initiated substance use by the eighth grade than non-Latinx and other Latinx youth . People generally respond to stress by showing increased negative emotion, decreased positive emotion, and activation of the HPA axis, a biological system especially sensitive to social-evaluative stressors .However,cannabis grow kit inability to mount a response or showing blunted reactivity to stress may suggest disengagement and has also been related to poorer well-being .
Dampened reactivity and recovery following stress have also been related to poorer health including depression and externalizing problems . Individuals can show blunted rather than exaggerated stress reactivity and recovery for many reasons . Individuals who experience chronic or repeated stress may initially show heightened emotional and biological stress reactivity and recovery, and these responses may habituate and show a blunted profile over time . Therefore, whereas unpredictable, acute stressful life events may promote a profile of exaggerated reactivity to stress, living in adversity can serve as a chronic stressor and consequently can promote inflexibility of psychobiological systems over time, such that individuals are incapable of responding to acute stressors . Indeed, youth and adults who experience more adversity generally show blunted rather than enhanced cortisol and heart rate reactivity to acute stress , as well as reduced activation of neural regions involved in threat such as the amygdala . It has been posited that individuals who experience high levels of adversity may be inclined to disengage from stressors, which can attenuate psychobiological reactivity and recovery . Lastly, low reactivity may result from socialization from peers and parents . For instance, youth who experience adversity may interact with deviant peers or bullies who prompt them to be less responsive to stress and may be socialized by parents to be less affected by daily stressors . Just as heavy substance use can dysregulate HPA axis function , dysregulation of the HPA axis may also contribute to substance use risk. Youth with blunted HPA axis reactivity to stress may lack physiological inhibitory control, such that they may be less inhibited by the social consequences of risk-taking compared to adolescents who show greater cortisol reactivity to stress . Alternatively, adolescents with chronic under arousal may be generally more inclined to pursue risky behaviors to promote physiological arousal . Youth may not show cortisol reactivity to a stressor because they are not sensitive to that stressor, or because they have already become elevated in anticipation of a stressor .
That is, certain youth may be more responsive to the threat such that they already show elevated levels of cortisol prior to stress onset and consequently show no further elevation in cortisol thereafter. Both blunted cortisol reactivity and anticipatory cortisol have been associated with more frequent substance use later in adolescence, especially among youth with difficulties in emotion regulation . Dysregulation of HPA axis function may similarly promote risk for lifetime substance use during adolescence. Adolescents with higher basal cortisol had earlier onset of substance use, although cortisol was not assessed following stress , and blunted cortisol secretion in anticipation of a laboratory task has been linked to greater substance use in pre-pubertal boys . Given the potential for bidirectional associations between HPA axis function and substance use, longitudinal studies are needed to disentangle whether HPA axis reactivity to and recovery from stress relate to risk for substance use onset during adolescence. Specifically, it is well-established that heavy substance use—as opposed to substance use initiation or less frequent substance use—can dysregulate physiology , so researchers may be best positioned to examine the role of physiology on substance use risk during adolescence when youth are initiating substance use but have not yet engaged in heavy substance use. In addition to cortisol reactivity, emotion reactivity to stress may relate to substance use. There are several emotion-related risk factors for substance use and substance use disorders in both adults and adolescents, including greater negative emotions, emotional lability, and emotional dysregulation . Although it is well-established that emotions influence frequency of substance use among users, it remains unclear whether emotion reactivity to stress relate to adolescents’ risk for substance use initiation. Emotion reactivity to stress often includes increases in negative emotions of both high arousal and low arousal and decreases in positive emotion, and each form of emotional change can have unique implications for health . Youth with exaggerated and dampened stress reactivity and recovery with respect to emotion may be particularly at risk for earlier onset of substance use, especially for Mexican-heritage adolescents, who experience culturally-specific stressors .
Therefore, research is needed to determine whether emotion reactivity to stress and recovery from stress is related to substance use and the emergence of substance use among these youth.The impact of stress reactivity and recovery on substance use during adolescence may vary by sex. Adolescents’ motivations for substance use differ by sex . Male youth tend to be more motivated to use substances for social enhancement whereas female adolescents are more motivated to use substances to cope with negative emotion and stress . Further, female adolescents show higher comorbidity between substance use and depression relative to male adolescents,cannabis grow supplies suggesting that emotion and stress may be particularly tied to female adolescents’ substance use . Therefore, although male adolescents tend to show earlier and more frequent substance use relative to female adolescents , substance use may be particularly related to the stress response among female adolescents. Indeed, prior research regarding youth who have used substances by age 16 in this cohort of Mexican-origin adolescents has found that greater cortisol reactivity relates to earlier age of initiation of alcohol use for girls, whereas blunted cortisol reactivity was related to earlier initiation of marijuana use only for boys with less advanced pubertal status . It is critical to disentangle whether differences in stress reactivity and recovery precede substance use across the sexes.Poverty status may also moderate associations between responses to stress and substance for two reasons. First, early life adversity including poverty status has been found to influence psychobiology such that youth who experience early life adversity, including youth below the poverty line, tend to show profiles of blunted cortisol responses to stress . Because these youth are already at heightened risk for blunted cortisol responses, the association between these responses and substance use may be stronger among these youth. Second, poverty status may influence adolescents’ propensity for substance use. Youth below the poverty line may experience earlier exposure to substance use and substance-related crime, more targeted marketing of substances, and lower parental involvement . They may also be more motivated to use substances for reasons beyond stress, such as due to boredom, sensation seeking, and pursuit of enhancing effects in order to compensate for a lack of pleasurable substance-free daily activities . Poverty status may similarly influence the types of substances that adolescents use. Whereas cigarette use is more common among youth with lower socioeconomic status, marijuana, alcohol, and vaping are generally more prevalent among more affluent youth, potentially due to differences in cost, availability, and social norms . As a result, associations between stress reactivity and recovery and certain substances may differ by poverty status. The present study investigated whether adolescents’ HPA axis and emotion responses to the Trier Social Stress Test , a validated paradigm for eliciting social-evaluative threat, were related to the use of various substances among Mexican-origin youth growing up in a low income, high-risk agricultural setting . Responses to a social stressor were selected because adolescents tend to be particularly responsive to social threats, compared to younger children and adults , and youth often use substances in peer contexts to reduce social stress or enhance social experiences.
In line with prior research highlighting how people vary in the types of emotions they experience in response to stress , we examined changes in three emotions following stress: anger, sadness, and happiness. Discrete emotions have different functional purposes and have unique impacts on cognitions and judgments . Therefore, rather than aggregating across emotions, we assessed unique effects of each emotion. We tested whether stress reactivity and recovery related to substance use among adolescents at heightened risk for substance use, in line with previous studies that have examined substance use initiation in high-risk samples . Most prior studies examining stress responses and substance use have been conducted in the context of adult substance users or with cross-sectional designs . Therefore, we employed a longitudinal design to disentangle whether dampened psychobiological stress reactivity and recovery at age 14 precede the emergence of substance use initiation by age 16. Models examined whether differences in adolescents’ HPA axis and emotion reactivity and recovery to the TSST at age 14 were related to a) use of substances by age 14, b) use of substances by age 16, and c) emergence of substance use between ages 14 and 16, excluding youth who had already used by age 14. Given the high levels of adversity in this sample, dampened psychobiological stress reactivity and recovery were predicted to be associated with use of alcohol and marijuana among these youth, in line with previous research . Although not previously tested with use of cigarettes and vaping, we examined whether dampened psychobiological reactivity and recovery would similarly relate to these substances which are also commonly used in adolescence. Finally, models examined whether associations between HPA axis and emotion stress reactivity and recovery and substance use differ by sex and poverty status. Given that female adolescents may be more inclined than male adolescents to use substances to reduce negative emotion , we predicted that associations between dampened stress reactivity and recovery and substance use would be stronger for female adolescents than male adolescents. Because poverty status can promote profiles of dampened reactivity and can influence the types of substances that youth use , we tested whether associations differ by poverty status.Adolescents provided four 1-2 mL saliva samples via passive drool throughout the task. They provided the first sample after spending over two hours in the laboratory environment, during which they completed benign surveys, and then resting in the lab for 10 min. The second sample was collected immediately after the TSST was completed, roughly 15 min. after TSST onset. The third sample was collected 30 min. after TSST onset, and the fourth and final sample was collected 60 min. after TSST onset. This sampling procedure was similar to previous administrations of the TSST .