An Integrative Review to Develop the Unified Neuromatrix Allostatic Load and Resiliency Model (UNALARM) and Apply It to the Health of Firefighters and Other Public Safety Personnel

A challenge in studying the health of firefighters and other public safety personnel (PSP) is the lack of a comprehensive model that integrates physical, psychological, and social health. A completely comprehensive model may exceed our knowledge and may not be practical. However, a model that better integrates different aspects of health can guide more holistic research, intervention design and policies. We conducted an integrative review focusing on the brain (neuromatrix) and physiologic stress response models (allostatic loading and general stress responses) that can cause mental and physical health changes. We summarized evidence on allostatic loading in firefighters and conducted a systematic review and meta-analysis to synthesize the risk for chronic pain due to psychological factors in PSP. This work informed the Unified Neuromatrix Allostatic Load and Resiliency Model (UNALARM). The theory focuses on how physical, social, and psychological factors (alarms or supports) contribute to allostatic loads that initiate adaptive responses in the brain neuromatrix and peripheral stress regulation systems, which influence thinking, memory and physiologic responses to manifest in physical (e.g. pain) and mental symptoms, leading to a changed health state. Where the system can adapt to the allostatic load, an elevated health state with better resiliency and capacity may occur. However, when allostatic loads exceed the individual’s adaptive capacity, then chronic stress, persistent symptoms, and maladaptive coping strategies result in a compromised, exhausted health state, which is less able to resist further loading. This model explains why firefighters and other PSP are at-risk of concurrent physical (musculoskeletal, cancer) and mental health illnesses (occupational stress injuries).