Neuroinflammation and Mitochondrial Dysfunction in Parkinson's Disease: Connecting Neuroimaging with Pathophysiology.

There is a pressing need for disease-modifying therapies in patients suffering from neurodegenerative diseases, including Parkinson's disease (PD). However, these disorders face unique challenges in clinical trial designs to assess the neuroprotective properties of potential drug candidates. One of these challenges relates to the often unknown individual disease mechanisms that would, however, be relevant for targeted treatment strategies. Neuroinflammation and mitochondrial dysfunction are two proposed pathophysiological hallmarks and are considered to be highly interconnected in PD. Innovative neuroimaging methods can potentially help to gain deeper insights into one's predominant disease mechanisms, can facilitate patient stratification in clinical trials, and could potentially map treatment responses. This review aims to highlight the role of neuroinflammation and mitochondrial dysfunction in patients with PD (PwPD). We will specifically introduce different neuroimaging modalities, their respective technical hurdles and challenges, and their implementation into clinical practice. We will gather preliminary evidence for their potential use in PD research and discuss opportunities for future clinical trials.

Iron- and Neuromelanin-Weighted Neuroimaging to Study Mitochondrial Dysfunction in Patients with Parkinson's Disease.

The underlying causes of Parkinson's disease are complex, and besides recent advances in elucidating relevant disease mechanisms, no disease-modifying treatments are currently available. One proposed pathophysiological hallmark is mitochondrial dysfunction, and a plethora of evidence points toward the interconnected nature of mitochondria in neuronal homeostasis. This also extends to iron and neuromelanin metabolism, two biochemical processes highly relevant to individual disease manifestation and progression. Modern neuroimaging methods help to gain in vivo insights into these intertwined pathways and may pave the road to individualized medicine in this debilitating disorder. In this narrative review, we will highlight the biological rationale for studying these pathways, how distinct neuroimaging methods can be applied in patients, their respective limitations, and which challenges need to be overcome for successful implementation in clinical studies.

Esquizofrenia resistente: Definiciones e Implicancias del concepto de Esquizofrenia Resistente a tratamiento / Treatment resistant schizophrenia: definitions and implications of the Treatment Resistant Schizophrenia concept

Resumen La esquizofrenia (EQZ) es una entidad clínica altamente heterogénea. Determina un severo impacto en la calidad de vida de los pacientes y un alto costo para la sociedad. Los antipsicóticos son la primera línea de tratamiento, sin embargo, hasta un tercio de los pacientes presentaran una esquizofrenia resistente a tratamiento (ERT). Se ha propuesto que la ERT podría corresponder a un grupo neurobiológicamente distinto de la enfermedad con una arquitectura genética particular y no solo al extremo del espectro de severidad de la misma. A pesar de ello, actualmente no existe consenso en la literatura en torno a la definición de ERT. En este trabajo presentamos una revisión de diferentes definiciones de ERT centrándonos principalmente en las guías clínicas publicadas. Además se discuten las alternativas terapéuticas en ERT y, finalmente, se proponen perspectivas futuras en torno a la necesidad de desarrollar predictores de respuesta a antipsicóticos de primera y segunda línea, así como también la posibilidad de comprender la neurobiología de la ERT.

Schizophrenia (SZ) is a highly heterogeneous clinical entity. It causes a severe disruption in quality of life, and it imposes a significant burden to society. Antipsychotics are the first line treatment, however up to a 30% of the patients will present resistance to treatment. Treatment resistant schizophrenia (TRS) could be a neurobiologically distinct disorder and not merely an extremely severe form of SZ. However, there is no consensus in the literature as to the definition of TRS. In the present work we review different definitions of TRS, mainly from clinical guidelines. Furthermore, we discuss therapeutic alternatives for TRS and suggest future perspectives regarding the identification of response predictors and understanding the neurobiology of TRS.