1. Introduction
Countless lives have been saved with antibiotics and vaccines for various communicable diseases [1,2]. However, chronic disease is currently the most significant burden on health systems globally and the cause of approximately 70% of deaths worldwide [3,4].
Alzheimer's disease (AD) and other neurodegenerative diseases have not specifically been included in those numbers and therefore the situation may be much worse. Approximately 45% of all Americans suffer from one or more chronic diseases [5].
In Europe, current estimates are that 50 million people live with multiple chronic conditions and this number is expected to increase during the next decade [6]. In 2015, dementia affected 47 million people worldwide (or roughly 5% of the world's elderly population), a figure that is predicted to increase to 75 million in 2030 and 132 million by 2050.
Recent reviews estimate that globally nearly 9.9 million people develop dementia each year. People diagnosed with one or more chronic conditions often have complex health needs, die prematurely and have poorer overall quality of life [3]. Patients with multiple chronic conditions generally receive ineffective, incomplete and fragmented care [6].
According to the Grattan Institute, ‘Australian primary care is failing in one crucial area: the prevention and management of chronic disease’ [4], and it is probably the same globally. Professor Allen D. Roses has provided two excellent reviews on the economics and future of using pharmacogenetics to produce drugs with greater efficacy and safety on a more personalized treatment basis instead of limited efficacy for 30–40% of medicated patients [7,8]. However, it may take another 10 years or more for clinically trialled drugs to be brought to market.
Medicinal drugs used to treat chronic illnesses need to be taken daily for the rest of each patient's life [9] and are therefore very profitable for the companies that produce them. These medicines, which provide symptomatic relief, are used in chronic diseases without the prospect of providing a cure. Unless there is a paradigm shift away from single-mode to multimodal medicines, or to combinations or cocktails of medicines which address all the factors of the disease process, it is unlikely that a cure will be found for chronic degenerative or neurodegenerative diseases [10,11].
Focusing research efforts, drug development strategies and healthcare approaches predicated on a single component of a system, rather than the interacting network of components comprising such a system, may obscure important aetiological principles and/or disease mechanisms, including those evident during presymptomatic stages of disease. The application of systems science and its extension into healthcare therefore posits that health and/or disease result from the dynamic interactions of an individual's intrinsic multiomic components (e.g. genetic, epigenetic, etc.), their resultant phenotype, and the extrinsic (environmental) factors influencing the intrinsic milieu [12,13].
A holistic approach to healthcare to delay and prevent chronic disease by lifestyle changes that optimize individual diet, exercise, sleep and stress reduction is beneficial. Nutrition is also a central tenet of functional or integrative medicine, traditional Chinese medicine, Ayurveda and naturopathic medicine [12,13].
It is imperative that effective treatments for chronic diseases are implemented, reducing hospitalizations and serious complications to improve the quality of life of patients and lower the ever-increasing cost of healthcare, which we all share [5,6,14]. Research has demonstrated that a natural approach to preventing, delaying, and even reversing chronic degenerative and neurodegenerative diseases is effective [15–40].
In this review, we will focus on nutritional, nutraceutical and antioxidant treatments of AD, although they can also be used in other chronic degenerative and neurodegenerative diseases.
