Journal of Pain & Relief
Open Access

Chronic pain; Mental health; Depression; Anxiety; PTSD; HPA axis; Comorbidity; Pain perception

Introduction

Chronic pain, defined as pain persisting for more than three to six months, affects millions worldwide and presents a major public health concern. Beyond its physical burden, chronic pain has profound psychological implications. Mental health disorders, especially depression and anxiety, are commonly reported among individuals with chronic pain. Conversely, patients with psychiatric conditions often develop persistent pain symptoms, even in the absence of identifiable physical causes. The intertwining of pain and mental health issues can exacerbate the experience of pain, contribute to disability, and hinder recovery. Recognizing the interconnectedness of chronic pain and mental health disorders is crucial for developing effective and sustainable treatment plans. This article provides an overview of how chronic pain and mental health influence each other, explores the underlying mechanisms, and proposes holistic, interdisciplinary approaches to management [1, 2].

Description

Understanding chronic pain

Chronic pain differs fundamentally from acute pain, which serves as a biological warning signal. In chronic pain, the protective purpose becomes obsolete, and pain becomes a disease in itself. Common chronic pain conditions include fibromyalgia, chronic back pain, osteoarthritis, neuropathic pain, and headache disorders. These conditions often involve changes in both the peripheral and central nervous systems, including neuroplastic alterations that increase sensitivity to pain—a phenomenon known as central sensitization [3].

Mental health disorders associated with chronic pain

Depression: Major depressive disorder is highly prevalent among chronic pain patients. It is characterized by feelings of sadness, hopelessness, low energy, and anhedonia. Depression may amplify pain perception and interfere with treatment adherence.

Anxiety disorders: Generalized anxiety disorder (GAD), panic disorder, and health anxiety are commonly seen in chronic pain populations. Anxiety increases vigilance and catastrophizing, both of which worsen the subjective experience of pain.

Post-traumatic stress disorder (PTSD): Especially common in populations with injury-related pain, PTSD is associated with heightened arousal and reactivity, intrusive thoughts, and emotional numbing. Pain can serve as a constant reminder of trauma, reinforcing symptoms [4, 5].

Somatization and health anxiety: Some individuals express psychological distress through bodily symptoms, a process known as somatization. This further complicates diagnosis and management.

Discussion

Biopsychosocial model of pain

The biopsychosocial model offers the most comprehensive framework for understanding chronic pain. It acknowledges that pain is not solely a biological phenomenon but is influenced by psychological and social factors. According to this model:

• Biological: Includes injury, inflammation, and nervous system changes.

• Psychological: Encompasses emotions, cognition, beliefs about pain, and past trauma.

• Social: Includes support systems, work status, and socioeconomic conditions.

All three domains interact to influence pain severity, disability, and the response to treatment.

Shared neurobiology

The brain’s pain matrix: Regions such as the anterior cingulate cortex (ACC), prefrontal cortex (PFC), insula, and amygdala are involved in both pain and emotion regulation. Disruption in these areas can lead to both increased pain perception and emotional dysregulation.

Neurotransmitter imbalance: Chronic pain and mood disorders share dysregulation in neurotransmitters such as serotonin, norepinephrine, dopamine, and gamma-aminobutyric acid (GABA). This underlies the rationale for using antidepressants like SNRIs and tricyclics for both depression and pain relief [6].

Hypothalamic-pituitary-adrenal (HPA) axis dysfunction: Chronic stress alters the HPA axis, leading to increased cortisol levels that can suppress the immune system, increase inflammation, and disrupt pain processing. Dysregulation of this axis is common in both chronic pain and depression.

Neuroplasticity and central sensitization: Emotional stress can induce plastic changes in the central nervous system, increasing the sensitivity to pain stimuli and leading to prolonged or exaggerated pain responses [7].

Inflammation and immune activation: Pro-inflammatory cytokines like IL-6 and TNF-alpha have been implicated in both depression and chronic pain. These cytokines may act on the central nervous system, creating a feedback loop of pain and mood dysfunction.

The bidirectional relationship

Pain and mental health influence each other bidirectionally:

Pain can lead to mental health disorders: Persistent pain can reduce quality of life, limit activity, impair sleep, and induce social isolation—all of which contribute to depression and anxiety.

Mental health disorders can worsen pain: Depression and anxiety alter pain processing in the brain, reduce pain thresholds, increase attention to pain, and hinder coping abilities [8].

For example, individuals with untreated depression are more likely to report high pain intensity, greater disability, and less satisfaction with treatment outcomes.

Barriers to effective management

Several barriers persist:

Stigma: Many patients hesitate to acknowledge psychological factors in pain for fear of being labeled or dismissed.

Fragmented care: Often, pain and mental health are treated in silos, resulting in disjointed and less effective care.

Over-reliance on medications: Opioids and other painkillers may be prescribed without addressing underlying emotional issues, leading to dependency and inadequate relief [9, 10].

Conclusion

Chronic pain and mental health disorders are intricately connected through shared neurobiological mechanisms and mutual reinforcement. Understanding this interplay is vital for developing effective, individualized pain management strategies. A purely biomedical approach to chronic pain is insufficient; instead, treatment must also encompass psychological and social dimensions. By adopting the biopsychosocial model, clinicians can better address the emotional and cognitive challenges that accompany chronic pain. Interventions that combine pharmacologic and non-pharmacologic modalities, particularly those that target both pain and mental health, show the most promise in improving outcomes. Ultimately, integrating mental health services into pain care is not an option—it is a necessity for holistic, compassionate, and effective treatment.