Allostatic Load and Allostatic Overload: Preventive and Clinical Implications (2025)

Allostasis, Allostatic Load, and Allostatic Overload

Allostasis has been defined as an organism’s capacity to achieve and maintain stability through change. The human brain being an “organ for predictive regulation of the internal milieu,” allostasis aims at optimal flexibility in response to anticipated changes or challenges [1]. A number of biological systems are involved in allostasis, including the cardiovascular, endocrine, immune, inflammatory, and autonomic nervous systems. As long as these systems work well, both physical and mental well-being are ensured. However, in times of long-lasting, chronic stress, allostatic load or allostatic overload may occur. According to McEwen and Stellar, allostatic load refers to “the strain on the body produced by systems under challenge and the changes in metabolism and wear and tear on a number of organs and tissues” [2]. On the cellular level, mitochondria seem to play a crucial role [3]. On the level of the individual, a number of biological as well as psychosocial correlates have been identified [4], while on the interpersonal level, social support is negatively related to allostatic load [5]. When environmental challenges exceed an individual’s ability to cope, the allostatic system becomes dysregulated and allostatic overload may ensue [6, 7]. Clinically, allostatic overload manifests in symptoms such as sleep disturbances, irritability, impaired social or occupational functioning, and feelings of being overwhelmed by the demands of daily life. If it persists, allostatic overload may ultimately result in physical and/or mental health problems [8]. However, it does not necessarily have a medical or psychiatric connotation but should rather be understood as a transdiagnostic categorization [8].

Clinical Applications of the Concept of Allostatic Load

In clinical practice, patients do not usually present with a certain, well-defined textbook diagnosis of an illness or disorder, but rather with a multitude of problems, signs, and symptoms. When it comes to clinical decision-making, biographical information, as well as biological markers, and, in case psychological issues are involved, psychometric data will need to be taken into consideration. This applies to somatic and psychosomatic medicine as well as to mental health. The clinical interview is the basis of every comprehensive health assessment. The wise clinician will apply the principles of clinimetrics [9–13], incorporate allostatic load parameters [4], and take into consideration additional biological markers if needed, in both diagnostic procedures and therapeutic recommendations [14].

Fava and colleagues [7] emphasized that “consideration of allostatic load allows clinicians to create individually tailored interventions to prevent or decrease the negative impact of environmental factors on health,” and that “healthy lifestyle behavior and euthymia may modulate the vulnerabilities induced by allostatic overload.” For instance, in endocrinology, taking allostatic load into account may lead to a better understanding of patients with regard to, e.g., maladaptive illness behavior, health-damaging lifestyle habits, and response to treatment or lack thereof [15]. Moreover, there is emerging evidence showing that allostatic load itself may be amenable to change: for example, cognitive behavioral therapy as well as Tai Chi Chih for insomnia, and group resilience training for women with metastatic breast cancer showed promising results in terms of reducing allostatic load parameters [16]. Fava and colleagues [7] recently introduced a staging system [17] to indicate where an individual is in the process of developing a clinical condition, with stage 0 standing for “euthymia” (i.e., functional allostasis), stages 1 and 2 representing allostatic load and overload, and stage 3 marking the onset of physical and/or mental illness [7].

There is now also an emerging body of literature on allostatic load in children and adolescents. Lucente and Guidi’s [18] systematic review in this issue reveals that greater allostatic load is associated with poorer mental and physical health outcomes in both clinical and non-clinical pediatric populations. Long-term investigations into the relationship between allostatic load and health outcomes are scarce, though, which is why we still need to be careful with regard to causal attributions. Moreover, all mental (i.e., emotional and cognitive) processes have their physiological correlates, and mental and physiological processes mutually influence each other [19]. It might thus be adequate to conceptualize allostatic load as a risk factor for health consequences in a broader sense, which entails both mental and physical aspects that are closely coupled and affect one another (e.g., [20]). Such a conceptualization aligns well with suggested clinical criteria for the assessment of allostatic overload, which include both psychosocial and physical symptoms [8].

Allostatic Load in Psychotraumatology

The concept of allostatic load is of particular relevance for the field of traumatic stress research and clinical practice. In allostatic load, it is the accumulation over time of the “wear and tear on a number of organs and tissues” [2] that leads to physiological dysregulation and ultimately, via allostatic overload, to physical or mental illness. Similarly, in traumatic stress, while there are certain types of potentially traumatic events (such as, e.g., torture or rape) that carry an especially high conditional risk of precipitating posttraumatic stress disorder (PTSD) [21], it is often striking how seemingly minor events (e.g., an accident without severe physical injuries) can result in PTSD as well. In such cases, we often find prior exposure to various isolated traumatic events, or a history of chronic, repetitive, sequential traumatization starting in childhood. Research has demonstrated that, depending on the number of traumatic events a person has been confronted with, at some point even the most resilient people will develop PTSD [21, 22]. Second, it is the subjective interpretation or meaning of a traumatic event, including the link the affected person makes to past trauma, rather than the event per se and its objective components that determine if and when PTSD develops and how severe the symptoms are. Again, the parallels with the concept of allostatic load, reflecting “the cumulative effects of experiences in daily life that involve ordinary events (subtle and long-standing life situations that may be experienced by the individual as taxing or exceeding his/her coping skills)” [7, 8, 18], are obvious.

In view of research findings demonstrating the strong relationship between both traumatic exposure and PTSD on the one hand, and physical health on the other hand, Schnurr and Green suggested a conceptual framework based on allostatic load, linking traumatic exposure and PTSD to physical health outcomes [23, 24]: On the one hand, traumatic exposure per se can lead to psychological and biological alterations as well as to dysfunctional attentional processes (e.g., altered symptom perception), which in turn impact negatively on health risk behaviors (e.g., substance abuse, smoking, poor self-care) and illness behavior, creating physical health problems. On the other hand, the model suggests that PTSD itself will lead to physical morbidity, including mortality, via the same pathways [24]. In fact, PTSD is strongly related to various physiological dysregulations. For instance, the hypothalamic-pituitary-adrenal axis as well as the inflammatory, cardiovascular, and metabolic systems were found to be malfunctioning in both PTSD and allostatic load [25]. Given that many of these systems are related to the cannabinoid system, Lohr and colleagues [25] have recently proposed that cannabinoid agonists might be used to address allostatic load pharmacologically in patients suffering from PTSD. Such approaches and their potential as isolated or add-on treatments to psychotherapeutic strategies (focusing on coping with stress, lifestyle modifications and emotional well-being; see [8]) deserve further exploration.

While PTSD can develop following various types of trauma across all ages, child maltreatment by definition occurs early in life and is typically characterized by repeated, sequential exposure to physical, emotional, and/or sexual trauma as well as neglect. Accordingly, in survivors of child maltreatment, allostatic load can occur early in life already, exerting its deleterious effects longitudinally throughout the lifespan [26–28]. In fact, child abuse and neglect predict not only allostatic load [29] but also physiological dysregulation and physical health in adulthood [30]. Furthermore, the concept of allostatic load is also used to explain the causal link between child maltreatment and accelerated biological aging [31]. Accordingly, it has been suggested that in providing treatment for child maltreatment survivors, the effects of allostatic load should be addressed [32].

Complex PTSD can occur after prolonged or repetitive distressing experiences such as child maltreatment. In addition to the typical symptoms of PTSD, complex PTSD includes symptoms in the social realm such as difficulties in sustaining relationships and in feeling close to others, and avoidance of social engagement [33]. Such impairments in social well-being are particularly concerning, given that supportive social relationships are inversely related not only to mental but also to physical health problems and are assumed to buffer or even counteract the deleterious effects of allostatic load and overload [27]. Thus, in patients with a history of child maltreatment, interventions that increase social well-being might be needed. Furthermore, experimental research suggests that individuals exposed to child maltreatment show generalized negative responses to socially relevant stimuli (e.g., neutral facial expressions, social touch) [34, 35] as well as a lowered threshold to respond to the presence of others with unpleasant emotions and physiological states (e.g., [36]), likely as a result of early negative social learning. In addition to treatments focusing on the enhancement of patients’ well-being [37, 38], interventions might thus target the development of a sense of safety, e.g., by means of body-oriented approaches [39, 40]. Such approaches might transdiagnostically reduce allostatic (over)load and its negative consequences as they specifically aim to change the body’s responses to trauma reminders by establishing emotion regulation capacities that diminish physiological arousal and increase patients’ capacity to relax [40, 41].

To sum up, conceptualizing allostatic load as a risk factor for mental and physical health impairments opens up opportunities for the development of empirically evaluated treatment options, focusing not only on the treatment of (mental or physical) disorder-specific symptoms but on transdiagnostically relevant processes such as perceived safety and well-being in social situations. Such interventions will contribute to health and well-being more broadly, not only taking into account but actually making use of the complex interactions between social, psychological, and biological processes. Interventions aiming to treat symptoms of allostatic overload are particularly relevant when it comes to working with patients who have been exposed to multiple stressors or to prolonged (traumatic) stress. Next to evaluating the potential of novel interventions such as body-oriented treatment approaches [39, 40], it is important to implement standardized interviews to screen for clinical manifestations of allostatic overload [8]. Additionally, screenings for child maltreatment as one of the most common, transdiagnostically relevant precursors of allostatic overload should become routine in both physical and mental health care services. Such screenings might also aid the implementation of early interventions, aiming to prevent the occurrence of allostatic overload and its long-term consequences as early on as possible in child and adult patient populations.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

No funding was received.

Author Contributions

Monique C. Pfaltz and Ulrich Schnyder contributed equally to this editorial.

Funding Statement

No funding was received.

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