Editorial

Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease. Inflammation has been observed in both the idiopathic and familial forms of PD. Importantly, PD is reported more often in men than in women, men having at least 1.5- fold higher risk to develop PD than women. This review summarizes the impact of biological sex and sex hormones on the neuroimmune contributions to PD and its investigation in animal models of PD. Innate and peripheral immune systems participate in the brain neuroinflammation of PD patients and is reproduced in neurotoxin, genetic and α-synuclein based models of PD. Microglia and astrocytes are the main cells of the innate immune system in the central nervous system and are the first to react to restore homeostasis in the brain. Analysis of serum immunoprofiles in female and male control and PD patients show that a great proportion of these markers differ between males and females. The relationship between cerebrospinal fluid inflammatory markers and PD clinical characteristics or PD biomarkers shows sex differences. Conversely, in animal models of PD, sex differences in inflammation are well documented and the beneficial effects of endogenous and exogenous estrogenic modulation in inflammation have been reported. Targeting neuroinflammation in PD is an emerging therapeutic option but gonadal drugs have not yet been investigated in this respect, thus offering new opportunities for sex specific treatments.

Disorders of the central nervous system are worldwide causes of morbidity and mortality. Neurological disorders pose a large burden on worldwide health. The Global Burden of Disease Study shows that the neurological disorders such as Alzheimer's and other dementias, Parkinson's disease, multiple sclerosis, epilepsy, muscular dystrophy, and headache disorders represent 3% of the worldwide. Neurological disorders are defined as an inappropriate or impaired function of the peripheral or CNS due to impaired electrical impulses throughout the nervous system that may show the heterogeneous symptoms according to the parts of the system, which is involved in these pathologic processes. Some growing evidence on brain inflammation, viral or bacterial infection, and genetic components of neurological disease has been collected during recent years. On the basis of this evidence, we focused on the association of brain inflammation, viral or bacterial infection, mitochondrial gene, and other genetic components or mutations with neurological disorders.

According to the findings obtained in the context of a Global Initiative on Neurology and Public Health carried out by the World Health Organization (WHO), there has been a lack of reliable and comparative data on services and other resources for neurological disorders in many parts of the world. In view of these findings and in collaboration with the World Federation of Neurology (WFN), WHO has recently organized an international Survey of Country Resources for Neurological Disorders, which involved 109 countries and covered over 90% of the world's population. This large WHO/WFN collaborative endeavour collected expert information on a number of aspects of neurological care provision around the world including availability of neurological services in primary care; human resources for neurological disorders; sub-specialized neurological services; primary method of financing of neurological care; and disability benefits for patients with neurological disorders. The WHO/WFN Survey results clearly demonstrate that there are inadequate resources for patients with neurological disorders in most parts of the world, and highlight inequalities in the access to neurological care across different populations, and in particular in those living in low-income countries and in developing regions of the world. The key findings of the WHO/WFN Survey including their impact on delivery of neurological care around the world are presented and discussed in this paper. The entire set of WHO/WFN Survey results including numerous tables, graphs and accompanying commentaries can be found in the WHO/WFN Atlas of Country Resources for Neurological Disorders, which is available on request from WHO or at http://www.who.int/mental_health/neurology/.

The World Health Organisation (WHO) occupies a unique position in the area of health care and represents a neutral platform that can be used to bring about international collaboration in research. International projects carried out by WHO follow public health principles and are devoted to problems and diseases that are frequent, cause severe disability and represent a significant burden on communities and societies all over the world. One of such projects is the WHO Global Initiative on Neurology and Public Health, which aims to increase public and professional awareness of the prevalence, severity and costs of neurological disorders as well as of the possibilities for their prevention. In the context of this Global Initiative and in order to raise awareness of the public health importance of Parkinson's disease, WHO has established a WHO Working Group on Parkinson's disease. The recommendations produced by this Working Group have guided WHO's work on public health aspects of Parkinson's disease including epidemiology, organisation of services and treatment, education, training and information, and direct and indirect costs of care.