Multiple sclerosis (MS) is a chronic, autoimmune pathology that affects the nervous system. It is characterized by inflammatory lesions that cause axonal damage with neurodegeneration. The signs and symptoms present in this pathology include among others, psychiatric disorders. In MS, depression is the most frequent psychiatric disorder, with prevalence levels of 40 to 60%; to date, the cause is unknown. The brain-derived neurotrophic factor (BDNF) is a neurotrophin related to neuroplasticity. The single-nucleotide polymorphism Val66Met, encoded by the BDNF gene, has been associated with various effects, including the presence of neuropsychiatric disorders. The purpose of our study was to evaluate the association between the BDNF Val66Met polymorphism and depression in MS patients. Methods: Study design, cases, and controls: Mexican mestizo MS patients. Cases: Patients diagnosed with depression. Controls: Patients without depression diagnosis. Measurements: For depression, the Beck Depression Inventory; for polymorphism, real-time PCR. Results: No statistically significant differences were found in sociodemographic and disease variables between the case and control groups. qPCR analysis showed that 68% of the participants were Val/Val wild-type homozygotes, 29% were Val/Met polymorphism heterozygotes, and 3% were Met/Met polymorphism homozygotes. The presence of the BDNF gene rs6265 polymorphism was associated with a 5.6-fold increase in the probability of depression in the cases compared to the controls. Conclusions: The BDNF Val66Met Polymorphism is associated with depression in Mexican mestizo patients diagnosed with MS.

Psychostimulants induce neuroplastic changes in the mesocorticolimbic system associated with the expression of the D2 receptor, which has two isoforms: D2long (D2L) and D2short (D2S). These isoforms seem to participate differentially in the plasticity changes induced by psychostimulants; however, the expression changes of this receptor induced by these substances remain unclear. Psychostimulants have a mechanism that involves the participation of monoamines, and there is evidence that the dopamine activation by modafinil (MOD) in combination with the serotonin activation by citalopram (CIT) enhances psychostimulant-like effects for this combination. The present study was designed to characterize the expression of the D2S, D2L isoforms and tyrosine hydroxylase in the medial prefrontal cortex, ventral tegmental area, nucleus accumbens and ventral pallidum of rats previously treated with modafinil alone or in combination with citalopram. Results show that MOD alone and co-administered with CIT induce overexpression of D2S and D2L in the ventral pallidum, and only the pretreatment with 60 mg MOD + 3 mg CIT generated a higher expression of D2L in the medial prefrontal cortex and ventral tegmental area. Tyrosine hydroxylase expression was reduced only with 60MOD +5 mg CIT in the nucleus accumbens. These findings suggest that MOD, alone or co-administered with CIT, produces differential changes in the D2R isoforms that coincide with the psychostimulant effects of these substances. This research highlights the importance of further exploring the expression and function of D2 receptors and their two isoforms, as such analyses will allow us to infer the pre- and post-synaptic modulation of these receptors on the reward system.

Background: Multiple Sclerosis (MS) is an inflammatory, autoimmune and neurodegenerative disease of the central nervous system that leads to the progressive loss of motor and sensory functions. Cognitive dysfunction is a common symptom that significantly affects quality of life and daily activities. The MS diagnosis involves progressive disability due to its neurodegenerative nature. Objective: to analyze the relationship between the Latin Norm Neuropsychological Assessment and Disability in Multiple Sclerosis (NLNAMS) battery and physical disability in patients with MS. Methods: A retrospective review of 100 medical records was conducted. Three sections of clinical information were analyzed: (1) sociodemographic data and medical history, (2) neurological examination including disability measures using the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Severity Score (MSS), and (3) neuropsychological assessment results obtained through the NLNAMS battery to evaluate cognitive functioning across multiple domains. Results: High correlations were observed between EDSS scores and performance on the Symbol Digit Modalities Test (SDMT) and the Hopkins Verbal Learning Test–Revised (HVLT-R), which assess attention, processing speed and memory. Strong correlations were also found between EDSS and performance on verbal fluency tests, Trail Making Test (TMT), Rey–Osterrieth Complex Figure copy (ROCF), and the Modified Wisconsin Card Sorting Test (M-WCST). No significant correlation with MSS was found. Conclusions: The neuropsychological evaluation conducted with the NLNAMS battery showed a relationship between physical disability in multiple sclerosis and the domains of attention, processing speed, and memory. Therefore, this battery may provide valuable information for disease monitoring and prognosis.