Fibromyalgia (FM) is a disorder characterized by widespread chronic pain, significant depression, and various neural abnormalities. Recent research suggests a reciprocal exacerbation mechanism between chronic pain and depression. In patients with FM, dysregulation of tryptophan (Trp) metabolism has been identified. Trp, an essential amino acid, serves as a precursor to serotonin (5-HT), a neuromodulator that influences mood, appetite, sleep, and pain perception through the receptors 5-HT1, 5-HT2, and 5-HT3. Additionally, Trp is involved in the kynurenine pathway, a critical route in the immune response, inflammation, and production of neuroactive substances and nicotinamide adenine dinucleotide (NAD+). The activation of this pathway by pro-inflammatory cytokines, such as tumor necrosis factor α (TNF-α) and interferon gamma (IFN-γ), leads to the production of kynurenic acid (KYNA), which has neuroprotective properties, and quinolinic acid (QA), which is neurotoxic. These findings underscore the crucial balance between Trp metabolism, 5-HT, and kynurenine, where an imbalance can contribute to the dual burden of pain and depression in patients with FM. This review proposes a novel therapeutic approach for FM pain management, focusing on inhibiting QA synthesis while co-administering selective serotonin reuptake inhibitors to potentially increase KYNA levels, thus dampening pain perception and improving patient outcomes.

Background: Treatment-resistant depression (TRD) represents a major clinical challenge and is increasingly associated with persistent neuroinflammatory processes. Evidence suggests that dysregulation of the immune system, particularly the imbalance between pro-inflammatory and anti-inflammatory cytokines, contributes to poor therapeutic response. In this context, interleukin-10 (IL-10) has emerged as a key mediator in regulating the inflammatory response. Objective: To systematically analyze the evidence on neuroimmune dysregulation in depression, with an emphasis on TRD, and to evaluate the potential role of IL-10 as a biomarker and modulator of therapeutic response. Methods: A systematic review was conducted in accordance with PRISMA guidelines. Fourteen studies were included, comprising randomized clinical trials, longitudinal studies, a prospective cohort study, and exploratory designs. Methodological quality was assessed using the RoB 2 tool and complementary approaches. Data were integrated through a qualitative analysis focused on inflammatory biomarkers and clinical outcomes. Results: The studies consistently showed an association between elevated levels of pro-inflammatory cytokines, such as IL-6 and TNF-α, and the severity of depressive symptoms, as well as reduced response to conventional treatments. Immunomodulatory interventions, including ketamine, pentoxifylline, and minocycline, were associated with clinical improvement, particularly in patients with elevated baseline inflammation. IL-10 appears to be involved in counter-regulatory neuroimmune processes associated with inflammatory balance. Conclusions: Neuroinflammation plays a central role in TRD. IL-10 may serve as a relevant biomarker and a potential target for personalized therapeutic strategies informed by immune profiles, through modulation of neuroinflammatory pathways.

Background: The long-haul symptoms of COVID-19 have not been properly attended, especially those of the central nervous system. Attention, memory and executive functioning are the three main cognitive symptoms reported for long COVID patients. To this day, neurorehabilitation therapy to alleviate these symptoms has not been proposed. Objectives: The current study aims to evaluate the effect of a neurorehabilitation intervention on the three most prevalent symptoms reported for long COVID in Mexican patients: memory, attention and executive functioning. Methods: Subjects were recruited at Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra and underwent a novel neurorehabilitation intervention for 6 months. Baseline measurements were taken using validated instruments (Neuropsi, BANFE and CCQ) before the intervention and after it. Results: A significant decrease in the normalized score of the Memory component of the Neuropsi Atención y Memoria III test was found after the intervention, along with a decrease in two components of the BANFE-III test. Conclusions: In the current study, a successful neuropsychology intervention for the main cognitive symptoms of long COVID in a Mexican population reduced subjective self-perceived complaints and objectively measured cognitive symptoms.