Annual Research Review: Puberty and the development of anhedonia - considering childhood adversity and inflammation

Neural and immune interactions linking early life stress and anhedonia

Early experiences of stress and adversity are associated with blunted reward sensitivity and altered reward learning. Meanwhile, anhedonia is characterized by impairments in reward processing, including motivation, effort, and pleasure. Early life stress (ELS) and anhedonia share psychological, behavioral, and neurobiological correlates, and the system-level interactions that give rise to anhedonia have yet to be fully appreciated. The proposed framework uses a multilevel, multisystem approach to aid in understanding neural-immune interactions that link ELS and anhedonia. The interactions linking anhedonia and ELS presented here include reduced reward sensitivity, alterations in hypothalamic-pituitary-adrenal (HPA) axis response, elevated inflammatory cytokines or physiological markers of stress, and blunted reward circuitry functioning along the mesocorticolimbic pathway. The clinical implications and areas for future research are also discussed. Ultimately, this research may inform the development of more specific and individualized treatments for anhedonia.

The Reward Positivity Mediates the Association Between Adverse Childhood Experiences and Anhedonia in Young Adults With Drug-Naïve Major Depressive Disorder

BACKGROUND

Current clinical studies have indicated that major depressive disorder (MDD) concurrent with adverse childhood experiences (ACEs) is associated with greater anhedonia. However, little is known about whether the change in reward sensitivity among young individuals with MDD and ACEs is related to anhedonia.

METHODS

We evaluated anhedonia and ACEs in 86 patients with MDD (31 with no or 1 ACE and 55 with 2 or more ACEs) and 44 healthy control participants. Then, participants completed the Iowa Gambling Task during electroencephalography to measure the reward positivity (RewP) and its difference (ΔRewP; gains minus losses). Furthermore, we constructed a mediation model to assess whether aberrant ΔRewP mediated the relationship between ACEs and anhedonia.

RESULTS

Compared with healthy control participants and MDD patients with no or 1 ACE, MDD patients with 2 or more ACEs had the most severe symptoms of anhedonia and impaired decision making and showed significantly reduced reward sensitivity (most blunted ΔRewP). More importantly, ΔRewP mediated the relationship between ACEs and anhedonia in MDD.

CONCLUSIONS

We found that the ΔRewP partially mediated the association between ACEs and anhedonia in patients with MDD, which provides evidence for the neurobiological basis of abnormal changes in the reward system in MDD individuals with early adverse experiences.

Understanding the paradox: anhedonia and the unexpected divergence from reward seeking during adolescence - A commentary on Gupta et al. (2024)

Anhedonia is a symptom encompassing reduced or absence of motivation and pleasure that often emerges in adolescence and conveys risk for different mental illnesses and other difficulties. In their review, Gupta, Eckstrand, and Forbes (Journal of Child Psychology and Psychiatry, 2024) present an empirically-based conceptual neurodevelopmental model of anhedonia whereby brain development and pubertal maturation create openness to vulnerability to anhedonia that is influenced by early life adversity and chronic inflammation. This commentary considers anhedonia as a paradox of adolescence given its juxtaposition to the expected developmental milestones of adolescence. It highlights the need to consider anhedonia in terms of both variability and universality of children's experiences and biological development, missed opportunities for social relationships and experiences, and forms and functions of rewards and anhedonia.

Brain alterations in adolescents with first-episode depression who have experienced adverse events: evidence from resting-state functional magnetic resonance imaging

Introduction

Adverse life events constitute primary risk factors for major depressive disorder (MDD), influencing brain function and structure. Adolescents, with their brains undergoing continuous development, are particularly susceptible to enduring impacts of adverse events.

Methods

We investigated differences and correlations among childhood trauma, negative life events, and alterations of brain function in adolescents with first-episode MDD. The study included 23 patients with MDD and 19 healthy controls, aged 10-19 years. All participants underwent resting-state functional magnetic resonance imaging and were assessed using the beck depression inventory, childhood trauma questionnaire, and adolescent self-rating life events checklist.

Results

Compared with healthy controls, participants with first-episode MDD were more likely to have experienced emotional abuse, physical neglect, interpersonal relationship problems, and learning stress (all p' < 0.05). These adverse life events were significantly correlated with alterations in brain functions (all p < 0.05).

Discussion

This study contributes novel evidence on the underlying process between adverse life events, brain function, and depression, emphasizing the significant neurophysiological impact of environmental factors.