**1. Introduction**

Dementia is a neurodegenerative disorder characterized by a progressive decline in multiple cognitive domains leading to deterioration of daily living activities, including social and professional functioning. The aging population has been increasing gradually, and in 1990, 26 countries with more than 2 million elderly citizens aged 65 years and older were identified. It is expected that by 2013 another 34 nations will be added in the list. On the other hand, calculations made in 2000 about the number of elderly peoples (over 65 years old) in the world reached the 420 million (7%), and they estimated around 1 billion by 2030 (12%), mainly in developing countries [1].

Without doubt, the most common form of dementia in elderly people is Alzheimer disease (AD), but it can occur even in patients with 40 years of age.

AD is a progressive disorder of multifactorial origin, well defined clinically with a number of biomarkers also well documented. According to the World Alzheimer Report from 2015, AD will increase exponentially as population ages being one of the biggest problems of our society in this century [2]. Currently, 46.8 million people live with dementia all over the world, and this number will be duplicated every 20 years. Today, the calculated incidence of dementia is 9.9 million new patients, one new one every 3.2 s.

The Monzino 80+ population-based study made in 2015 found that one quarter of 80+-yearold person had dementia even in advanced stages which increased prevalence in extreme ages such as: 15.7% in persons aged 70–84 years to 52 and 65.9% in peoples aged 95–99 and in beyond 100 years, accordingly [3].

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Another author reports that 24.3 million patients have dementia at the present moment, and the incidence is 4.6 new cases yearly. They said the number of patients will be duplicated every 20 years to more than 81 million (71%) by 2040 most of them in developing nations [4]. Other author highlighted that the number of patients living with dementia (PLWD) will be a triple by 2050 [5].

The Greek statesman and poet Solon established that if a male people's loss his capacity for judgment due to old age then terms of man's will might be invalidated, this happened in 550 BC and the Chinese authors considered the medical term of dementia related to "foolish

Introductory Chapter: Cognitive Disorders and Its Historical Background

http://dx.doi.org/10.5772/intechopen.77084

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Two ancient Greeks Aristotle and Plato (**Figures 1** and **2**) wrote about mental decay in elderly persons and they considered that process as an inevitable one affecting all old peoples without possibility of its prevention. They also said that these kinds of person were not suitable to carry out high responsibilities or any position because this disorder affects their judgment,

A more advanced statement about dementia was established by Cicero who defined it as a process not inevitable related with the aging that "*affect only those old men who were weak-willed*." Cicero also said that dementia could not happen in those persons who remained mentally active and with the capacity to learn new things. Unfortunately, the Aristotle's medical writing prevailed for several centuries above the most modern Cicero's views on aging, and other physicians such as Galen and Celsus simply highlighted the Aristotle's belief [13]. Nevertheless, other authors from Greece and Rome delivered other ideas more similar to our modern concept of dementia including many cognitive and behavioral symptoms of dementia [14].

*May et al. [15] delivered the results of electronic searches of Zhong Hua Yi Dian ("Encyclopaedia of Traditional Chinese Medicine"), a CD of 1000 premodern (before 1950) medical books, for single herbs,* 

They found 127 different books containing 731 citations about products for treatment of memory disorders. A total of 110 natural products for the management of memory problems were identified including yuan zhi (Polygala tenuifolia), fu shen (Poria cocos), and chang pu (Acorus spp.) All the above-mentioned products have been cited many times in the literature over the past 180 years.

**Figure 1.** Roman copy in marble of a Greek bronze bust of Aristotle by Lysippos, c. 330 BC. The alabaster mantle is modern. Born 384 BC in Northen Greece. Died 322 BC in Euboea Greece (Source: https://en.wikipedia.org/wiki/Aristotle).

*and other natural products used for dementia, memory disorders, and memory improvement.*

old person" [11].

imagination, reasoning and memory [12].

We also agree with Vito Moretti [6] who wrote about "Update on Dementia" that the whole society should be involved in the mental health promotion to reduce risk of dementia and in new priorities for research purposes to identify new approaches to this problem and eradicate stigma and discrimination.

The delivery of therapeutic agents specifically designed to enhance memory and cognition in AD patients is increasing gradually. The limited efficacy of the drugs currently available is well known, and the introduction of these medications has shed an entirely new light on the field. Therefore, we believe that this is the best time to look at the past to understand the present and perhaps gain insight into the future [7].
