Endocrine News Podcast Episode 90: Early Life Stress and Substance Use
Date: September 4, 2024
Host: Aaron Lohr (A)
Guest: Dr. Alexandra Donovan (B), Charles R. Drew University of Medicine and Science

Overview: Main Theme and Purpose

This episode explores how early life stress affects the risk of substance use initiation in youth, focusing on the interplay between childhood experiences, puberty, hormone levels, and sex differences. Host Aaron Lohr interviews Dr. Alexandra Donovan, who presents findings from her research using data from the Adolescent Brain Cognitive Development (ABCD) Study. Key topics include the types and prevalence of early life stress, their physiological and psychological consequences, the moderating role of puberty and sex hormones, and the implications for substance use in adolescence.

Key Discussion Points & Insights

1. Defining Early Life Stress (01:02–02:52)

• Description: Early life stress (ELS) encompasses a range of negative experiences including abuse, neglect, family conflict, parental incarceration, socioeconomic hardship, and other chronic or intense stressors.
• Prevalence:
  • 61% of Americans report at least one ELS factor.
  • 17% have four or more ELS factors, associated with higher risks for heart disease, depression, substance use disorders.
• Impact: ELS is linked to physiological changes ("programming") in body systems, especially those related to stress and mental health.

“So early life stress is negative experiences that span the range from abuse to neglect to family conflict...it's the experiences of stress that are extremely large or chronic as well, and it's fairly prevalent.” – Dr. Donovan, (01:24)

2. The Intersection of ELS, Puberty, and Endocrine Systems (02:52–06:58)

• Puberty’s Role: Puberty is a transitional period where the brain and body (especially stress and sex hormone axes: HPA and HPG) undergo significant development.
• Physiological Mechanisms:
  • The hypothalamic-pituitary-adrenal (HPA) axis: Central to stress response; becomes more active during adolescence.
  • The hypothalamic-pituitary-gonadal (HPG) axis: Controls sex hormone production; interacts with the stress system.
• Programming Effects: Chronic early stress leads the body to adapt, potentially altering hormonal responsivity and brain circuitry related to decision-making and emotional regulation.
• Sex Differences: Emerging sex differences during puberty, with hormones “growing the brain” and influencing social and emotional behaviors differently.

“So there's an HPA and HPG axis and they talk back and forth to one another…in adulthood, it’s a direct activity of one suppresses activity of the other, whereas in growing it’s less clear.” – Dr. Donovan, (03:46)

3. Study Design & Approach (07:13–11:52)

• Research Questions: Investigate how different domains of ELS (environmental, family, traumatic events) predict substance use initiation by age 13, and whether these pathways differ by biological sex.
• Data Source: ABCD Study—a large, longitudinal cohort of U.S. youth starting at ages 9-10, with rich behavioral and biological data (including surveys from both parents and children).
• Domains Examined:
  • Environmental: Parental education, marital status, neighborhood income.
  • Family: Family history of psychopathology, family conflict, level of emotional support.
  • Traumatic Events: Abuse, witnessing domestic/neighborhood violence.
• Substance Use Measurement: Initial use of alcohol, nicotine (all products), or marijuana by age 13.

“The background literature on all these topics is more of a mosaic than a pathway...My hypothesis is that early life stress sets up this altered HPA axis function, which then throws off HPG axis function.” – Dr. Donovan, (07:18)

4. Main Findings & Surprising Results (11:59–17:58)

• Sex-Specific Patterns:
  • Males: Substance use (especially nicotine) more tightly linked to traumatic ELS (abuse, neglect, community violence).
  • Females: Substance use more associated with environmental/low-resource stressors.
  • Both Sexes: Family-related stress factors predicted substance use initiation.
• Overall Trend: Total ELS exposure correlated with higher risk for initiating substance use—even by age 13, at relatively low overall usage rates.
• Significance: Effects seen in a broadly representative, national sample, not just in high-risk subgroups. Database oversampling ensures racial and ethnic diversity.

“I was surprised to find that males had more of a response to the trauma events...for males, they’re more likely to use nicotine if they have more of a history of those traumatic events. That wasn’t the same in females.” – Dr. Donovan, (11:59)

“What was different in females...they were more likely to use substances by age 13 if they came from a low-resourced environment.” – Dr. Donovan, (13:54)

“Both males and females had a response that overall...early life stress, the higher amount...the increase in risk you had for starting any substance.” – Dr. Donovan, (15:21)

5. Potential Explanations for Sex Differences (18:16–20:41)

• Externalizing vs. Internalizing Pathways:
  • Males: More likely to externalize (e.g., oppositional behavior, conduct disorders)—may explain higher nicotine use in response to traumatic ELS.
  • Females: More likely to internalize (depression, anxiety, rumination).
• Puberty Timing: Low-resource environments often linked to earlier puberty in girls, which is associated with higher risk for depression, anxiety, and substance use.
• Study Limitations: Timing of puberty or stress exposure may further clarify observed sex differences; future analysis planned.

“There’s this idea of males tend to go the externalizing pathway...whereas females go the internalizing pathway…So it may be that we're seeing the males are using nicotine and it's part of this externalizing pathway.” – Dr. Donovan, (18:29)

6. Next Steps & Ongoing Research (20:41–23:35)

• Incorporating Hormone Data: Integration of salivary hormone measurements (DHEA, estradiol, testosterone) to clarify hormonal contributions to behaviors.
• Early Results:
  • Higher testosterone in females linked to alcohol use.
  • Higher estradiol in females linked to nicotine use.
• Future Directions: Stratification by pubertal timing, more detailed longitudinal analysis, consideration of further physiological and metabolic markers.
• Research Philosophy: Emphasis on holistic, interdisciplinary science spanning molecular to social levels.

“Higher levels of testosterone within females was associated with using alcohol, and higher levels of estradiol within females was associated with using nicotine.” – Dr. Donovan, (22:16)

“The more I'm here at the ENDO conference, the more other things I think about...It’s really great to see the academic silos being broken down as people are incorporating a more holistic view of the body.” – Dr. Donovan, (23:13)

Notable Quotes & Memorable Moments

• On Prevalence of Early Life Stress:
  “The latest CDC figures that I looked up said about 61% of Americans have at least one factor...About 17% have four or more early life stressors, and that tends to be the group that is suffering the most.” (01:45)

• On Brain and Hormone Development in Adolescence:
  “You have your prefrontal cortex and your executive decision making areas...growing and developing at that time. And part of that is connectivity to limbic systems and stress systems.” (03:21)

• On Surprising Results:
  “I was surprised a bit that it was already present so soon. It was a strong enough effect that we were able to detect it...even just 5% of that within that group, we were able to see who's connected and who used, who didn't use.” (15:35)

• On Breaking Negative Intergenerational Cycles:
  “Your parents don't know how to teach you good coping skills, you never pick up good coping skills. You have kids, you don't know how to teach them good coping skills. And cycles continues. The cycle continues.” (17:45)

Timestamps for Important Segments

• [01:24] – Defining early life stress and its prevalence
• [03:00] – Neuroendocrine changes in adolescence and interplay with stress
• [07:13] – Study design: ELS domains and ABCD Study overview
• [11:59] – Main findings, sex-specific pathways
• [18:16] – Discussion of externalizing/internalizing behavior and puberty timing
• [20:47] – Future research: adding hormone measures, early findings
• [23:13] – The importance of holistic, systems-based research

Tone and Language

Dr. Donovan communicates with enthusiasm, curiosity, and a commitment to science that bridges disciplines and methodologies. She emphasizes the importance of understanding both biological and social determinants of health and encourages broader, more inclusive research.

Summary for Listeners

This episode offers an insightful exploration of the links between early life stress, adolescence, hormones, and substance use, highlighting key differences in risk factors between males and females. Dr. Donovan’s work demonstrates that not only do social and environmental factors impact health outcomes, but biological transitions—particularly puberty—can modulate these risks in sex-specific ways. As the research evolves to incorporate precise hormonal and developmental markers, it underscores the nuanced, interconnected nature of youth health and behavior.

Listeners gain an understanding of the mechanisms by which early adversity "gets under the skin" and shapes trajectories into adolescence, with clear takeaways for parents, clinicians, and researchers interested in preventative health and the biology of stress.