**2. Methodology**

the loss of cognitive and motor functions associated with the CNS. The causes that trigger this neuronal death are still unknown, but clinical evidence demonstrates that age is an impor‐ tant risk factor and that the number of people suffering from dementia and other neurodege‐ nerative conditions will increase as a consequence of increased life expectancies [1]. The main diseases that are defined by neurodegenerative processes are: AD and PD, but this term also includes other conditions such as amyotrophic lateral sclerosis (ALS), multiple sclerosis and products of viral infections. These diseases have an impact not only on the individual suffering from the disease but also on their families, causing social isolation, family misunderstand‐ ing, and loss of friendships and social ties [2]. This is an important issue and should be further considered, especially because itis currently estimated that 94% of people living with dementia are cared for at home, generating an important amount of distress and economic burden on their closest relatives. This is particularly true for many low- and middle-income countries, where in many cases patients and caregivers have access only to limited support from the state

According to epidemiological data from the "World Alzheimer Report 2015" [3], there are more than 46 million people with dementia worldwide, and it is estimated that this number will increase to 131.5 million by 2050. Moreover, it is also important to consider that this type of disease carries a huge economic impact. Currently, only AD monetarily translates in US \$818 million per year globally and is estimated to be billions of dollars by 2018 [3]. This amount will certainly rise significantly if we consider other neurodegenerative diseases mentioned above. The reasons that trigger neurodegenerative processes in these diseases remain unclear, especially considering the many variables that are involved in their development. One of these variables, inflammation, became more relevant in recent years. One example is the evidence that exists today on neurodegeneration induced by viral infections [1, 4], as it involves the interaction of the CNS, environmental factors, and immune response. In parallel there are also studies that link the rising number of mild proinflammatory conditions described with major degenerative diseases of the elderly [5]. Thus, the major pathologies, associated with aging and increased physical frailty, are also associated with changes in body composition, energy imbalance, homeostatic dysregulation, and neurodegeneration. Chronic inflammation is

The inflammatory response is triggered to fight and control an injury, infection or other stimulus and may involve many cell types. The impact of the response is dependent on the numerous factors secreted by these cells, and they have the ability to self-regulate their response in order to repair tissue damage and to eliminate pathogenic elements. But when the response is prolonged in time, it causes a chronic inflammatory environment that leads to progressive tissue damage [6]. One of the evidences that support the relation between inflammation and increasing age is given by the increase in inflammatory mediators IL-6 and IL-8 and the rise in C-reactive protein in men and women with age, and the fact that these

In this chapter, we present a complete summary of the neuroinflammatory process and we explain how it relates to the development of features of neurodegeneration and neuronal death as in dementia neuropathology. We describe the neuroinflammatory processes considering

strongly connected to each of these aging phenotypes [6].

values also increase in obesity and neurodegenerative diseases [7].

and health providers.

18 Update on Dementia

We performed a detailed assessment of current evidence about main and nascent topics in the area of "Neuroinflammation and Neurodegeneration." Additionally, we focused our search in the three prototypic neurodegenerative diseases, considering classical concepts on neuro‐ pathology and incorporating new evidence on the role of neuroinflammatory process.

The focus of this review is to show evidence on common pathological role of neuroinflamma‐ tory process and microglial cells in neurodegenerative diseases, proposing a new approach for research of these diseases, in order to give support for the development of innovative therapies.

We performed a systematic search in the main database of National Center for Biotechnology Information Database (PubMed). Key words were: *inflammatory response*, *neuroinflammation*, *neurodegeneration*, *neurodegenerative diseases*, *neuronal death*, *microglial cells*, *microgliosis*, *Parkin‐ son disease*, *Alzheimer disease and Amyotrophic Lateral Sclerosis*.
