How does feeling pain look like in depression: A review of functional neuroimaging studies

Prozac exposure during adolescence increases pain sensitivity in adulthood

Psychotropic medication prescription rates, particularly of the selective serotonin reuptake inhibitor fluoxetine (FLX; Prozac), are on the rise in the female adolescent population. Particularly, because FLX is dispensed for the treatment of numerous mood-related illnesses, premenstrual dysphoric disorder, as well as for pain management. Although FLX is deemed efficacious shortly post/during chronic treatment, the potential for unexpected long-term side effects has not been thoroughly assessed. For this reason, in this brief report, we examined whether exposure to FLX, during adolescence, influences thermal nociception in adulthood. To do this, postnatal day (PD)-35 female C57BL/6 mice were exposed to FLX (250 mg/L in drinking water) for 15 consecutive days (PD35-49). Once mice reached adulthood (PD70) they were evaluated on thermal nociception sensitivity adopting the hot plate test. We found that adult mice with FLX history displayed reductions in body weight (g) as well as reduced time (s) to display hindpaw-licking behavior, when compared to controls. These outcomes suggest that juvenile FLX exposure induces thermal hyperalgesia in adulthood, thus questioning the safety of antidepressant exposure during early-life stages of development in the female population.

Altered Amplitude of Low-Frequency Fluctuation of the Brain Regions Associated with Pain Symptoms and Negative Emotion in Trigeminal Neuralgia

OBJECTIVE

Using whole-brain functional magnetic resonance imaging, we aimed to investigate abnormal spontaneous brain activity in the resting state of patients with trigeminal neuralgia (TN) and explore their relationship with pain symptoms and negative emotions.

METHODS

This study included 46 patients with TN diagnosed at our hospital from December 2022 to June 2023 and 35 healthy controls. All patients with TN completed questionnaires related to pain and emotions. The data analysis compared amplitude of low-frequency fluctuation (ALFF) in the brain between TN and healthy control groups. Pearson correlation analysis was used to explore the intricate relationships between pain symptoms, negative emotions, and brain functional abnormalities in patients with TN.

RESULTS

Compared with healthy controls, patients with TN exhibited significantly reduced ALFF in the left superior frontal gyrus (SFG), bilateral middle frontal gyrus, bilateral inferior frontal gyrus, right precentral gyrus, right superior temporal gyrus, bilateral middle temporal gyrus, left inferior temporal gyrus, and right cingulate gyrus (CG) (P < 0.05). In correlation analysis, ALFF in the left SFG and right CG was negatively correlated with pain symptoms and negative emotions in patients with TN.

CONCLUSIONS

Patients with TN show functional abnormalities in several key brain regions that are involved in pain perception and emotion regulation. These abnormalities primarily manifest as a reduction in spontaneous neural activity. ALFF in the left SFG and right CG is negatively correlated with the severity of pain and negative emotions, indicating that as pain and negative emotions become more severe in patients with TN, neural activity decreases more significantly in specific brain regions. This suggests that the left SFG and right CG may be characteristic brain regions in the pathophysiological mechanism of TN.

Chronic Pain and Comorbid Emotional Disorders: Neural Circuitry and Neuroimmunity Pathways

Chronic pain is a multidimensional experience that not only involves persistent nociception but is also frequently accompanied by significant emotional disorders, such as anxiety and depression, which complicate its management and amplify its impact. This review provides an in-depth exploration of the neurobiological mechanisms underlying the comorbidity of chronic pain and emotional disturbances. Key areas of focus include the dysregulation of major neurotransmitter systems (serotonin, gamma-aminobutyric acid, and glutamate) and the resulting functional remodeling of critical neural circuits implicated in pain processing, emotional regulation, and reward. Given the contribution of neuroimmune mechanisms to pain chronicity and mood disorders, we further conducted an in-depth investigation into the role of neuroimmune factors, including resident immune cells, infiltrating immune cells, and the release of inflammatory mediators. This review further discusses current therapeutic strategies, encompassing pharmacological interventions, neuromodulation, and integrative approaches, and emphasizes the necessity of targeted treatments that address both pain and emotional components. Finally, it identifies gaps in the current understanding and outlines future research directions aimed at elucidating the complex interplay between chronic pain and emotional disorders, thereby laying the foundation for more effective and holistic treatment paradigms.

Associations between somatic symptoms and remission of major depressive disorder: A longitudinal study in China

Previous studies have documented negative associations between somatic symptoms and remission of major depressive disorder (MDD). However, the correlations of specific somatic symptoms with remission remain uncertain. We aimed to explore the associations between specific somatic symptoms and remission focusing on sex differences among patients with MDD. We used data from patients with MDD in the Depression Cohort in China. At baseline, total somatic symptoms were evaluated using the 28-item Somatic Symptoms Inventory and were categorized into pain, autonomic, energy, and central nervous system (CNS) symptoms. To measure remission of MDD, depressive symptoms were evaluated using the Patient Health Questionnaire-9 after 3 months of treatment. We ultimately included 634 patients. Compared with quartile 1 of total somatic symptom scores, the full-adjusted ORs (95% CIs) for remission from quartile 2 to quartile 4 were 0.52 (0.30, 0.90), 0.44 (0.23, 0.83), and 0.36 (0.17, 0.75), respectively (P-value for trend = 0.005). The restricted cubic spline showed no non-linear associations between total somatic symptoms with remission (P-value for non-linear = 0.238). Pain, autonomic, and CNS symptoms showed similar results. Sex-stratified analysis showed that total somatic symptoms, pain symptoms, and autonomic symptoms were negatively correlated with remission in females, whereas CNS symptoms were negatively associated with remission in males. Our findings indicate that specific somatic symptoms exert differential effects on remission of MDD. Therapeutic interventions that target pain, autonomic, and CNS symptoms may increase the probability of remission. Furthermore, interventions for somatic symptoms should be tailored by sex, and females deserve more attention.