About this Research Topic
A quarter of patients present multiple health problems; More than half of those with a chronic disorder. However, the role of comorbidity (co-occurrence of two diseases) or multimorbidity (co-occurrence of two or more diseases) in medical research and practice is relatively unexplored in comparison to that of individual diseases. Complex disorders, arising from the combined effect of multiple genes and their interactions with the environment, including cancers, neurological disorders or endocrine diseases, are leading causes of global disease burden and mortality. A better understanding of the connections and interactions between these disorders could improve the quality of life and healthcare outcome of millions worldwide.
The development of large-scale genomics and proteomics methods, large medical databases and new systems biology approaches, now allows us to examine complex disorder relationships. There is, for example, an ongoing debate on the associations between cancers and CNS disorders. Certain combinations of cancers and CNS disorders co-occur more while others co-occur less often than expected by chance. Multiple Sclerosis for instance, is associated with a higher risk of developing brain tumors, pointing to a direct comorbidity between these diseases. Contrarily, numerous epidemiological and clinical studies revealed that Parkinson’s or Alzheimer’s diseases seem to lower the risk of developing certain forms of cancer, including solid or smoking-related tumors. This apparent protective anticancer effect, which we have termed ‘inverse cancer comorbidity’, seems to be produced by many serious central nervous system and immune disorders.
We believe that a better understanding of the direct and inverse comorbidities between complex disorders could improve the diagnosis, prognosis and knowledge on the molecular bases leading to the emergence of these diseases and could direct drug repositioning. For instance, understanding why people with certain CNS disorders are protected against certain forms of cancer could be the key to finding novel treatments for both conditions.
In this Frontiers Research Topic, we wish to explore the different research fields and interdisciplinary approaches that will have an impact on the study of comorbidities. Epidemiological and clinical population studies can reveal statistical associations between complex disorders. Bioinformatics, with the integrative analysis of massive post-genomic data, offers an interesting avenue for the understanding of comorbidities while studying, for instance, the participation of genes at the level of pathways and networks. Molecular biology can address the molecular mechanisms that could account for comorbidities at the cellular level. Finally, all these interdisciplinary approaches are linked by the shared final goal of finding new drugs and improving medical care.
We welcome and encourage submission of original papers, scholarly reviews, comments and hypotheses about any aspect of nosology, epidemiology, genomics, bioinformatics, clinical and overall systems medicine of direct and inverse comorbidities in people with complex disorders.
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.