 Introduction/Background Degenerative disease of the central nervous system is a growing public health concern. The prevalence of dementia, one of the leading degenerative conditions, is expected to quadruple by 2050 [1]. Other degenerative diseases may affect the extrapyramidal system and the motor system. Dementia is characterized by a significant loss of function in multiple cognitive domains without affecting the general level of arousal. Several forms are now recognized, including Alzheimer disease (AD), frontotemporal dementia (FTD), Lewy bodies disease, vascular dementia (VaD), and mixed dementias [2]. Although the causes of most dementias remain elusive, genetic research has opened many frontiers to understanding the pathophysiology of heretofore enigmas such as AD [1,3]. Additionally, infectious, autoimmune, and toxic etiologies have become increasingly more appreciated as causes of cognitive decline. Trauma with brain injury may also be associated with premature dementia. AD dementia is part of a continuum of clinical and biological phenomena. The workgroup emphasizes that AD dementia is fundamentally a clinical diagnosis. To make a diagnosis of AD dementia with biomarker support, the core clinical diagnosis of AD dementia must first be satisfied. In these recommendations, the term mild cognitive impairment (MCI) that is due to AD is used to refer to the symptomatic predementia phase of AD [5]. Similar to AD dementia, MCI that is due to AD cannot be currently diagnosed by a laboratory test but requires the judgment of a clinician. In addition, similar to AD dementia, etiologies in addition to AD pathophysiological processes may coexist in an individual that meets the criteria for MCI that is due to AD but in whom the AD pathophysiological process is the main cause of the cognitive dysfunction.
Dementia.  Introduction/Background Degenerative disease of the central nervous system is a growing public health concern. The prevalence of dementia, one of the leading degenerative conditions, is expected to quadruple by 2050 [1]. Other degenerative diseases may affect the extrapyramidal system and the motor system. Dementia is characterized by a significant loss of function in multiple cognitive domains without affecting the general level of arousal. Several forms are now recognized, including Alzheimer disease (AD), frontotemporal dementia (FTD), Lewy bodies disease, vascular dementia (VaD), and mixed dementias [2]. Although the causes of most dementias remain elusive, genetic research has opened many frontiers to understanding the pathophysiology of heretofore enigmas such as AD [1,3]. Additionally, infectious, autoimmune, and toxic etiologies have become increasingly more appreciated as causes of cognitive decline. Trauma with brain injury may also be associated with premature dementia. AD dementia is part of a continuum of clinical and biological phenomena. The workgroup emphasizes that AD dementia is fundamentally a clinical diagnosis. To make a diagnosis of AD dementia with biomarker support, the core clinical diagnosis of AD dementia must first be satisfied. In these recommendations, the term mild cognitive impairment (MCI) that is due to AD is used to refer to the symptomatic predementia phase of AD [5]. Similar to AD dementia, MCI that is due to AD cannot be currently diagnosed by a laboratory test but requires the judgment of a clinician. In addition, similar to AD dementia, etiologies in addition to AD pathophysiological processes may coexist in an individual that meets the criteria for MCI that is due to AD but in whom the AD pathophysiological process is the main cause of the cognitive dysfunction.