Evidence Building in Ayurveda: Generating the New and Optimizing the Old Could Be Strategic
Despite their traditional prevalence and new-found popularity, traditional systems of medicine have faced allegations of being healthcare practices based on empirical, anecdotal or experiential evidence bases. Ayurveda has been no exception to this; if anything, due to its connection to living systems of religion (unlike in Chinese medicine), the allegations against Ayurveda are stronger. These allegations mostly arise from the dominant scientific stream of laboratory-based modern medicine, which occupies not only the major share in national healthcare systems but also exercises a disproportionately large influence on the minds of policy-makers. To develop Ayurveda into a dependable, reliable and reproducible system of medicine, the ayurvedic intellectual fraternity must make a concerted effort to examine the science of evidence-building in Ayurveda (Singh 2010a).
One of the features which distinguishes a traditional system of medicine from folk medicine is the presence of a systematic organization of its knowledge, a sort of higher order of learning.
All textbooks in the ayurvedic canon exhibit this property, by being organized into sections of fundamentals (siitra) passing through cause and diagnostics (nidana), treatment (cikitsa), prognosis (indriya) and successful intervention (siddhi). As an illustration, the organization of Caraka Samhita is presented (Figure 7.1). Since most of these texts were composed at a time when the knowledge base and practice of Ayurveda was flourishing, one may conclude that the very existence of such a higher order of learning indicates a certain level of sophistication and intelligence in the process. By having such an organization, Ayurveda has risen above the random and chance-based approach of folk medicine.
FIGURE 7.1 Organizational order of Caraka Samhita.
In between the hardened skeptics and the blind followers of Ayurveda, there exists a not-insig- nificant population of moderate practitioners and academics of Ayurveda, who have sought to demystify, decode and interpret the principles of Ayurveda using the language and logic of modern science (Rastogi and Singh 2012). This population of moderate in-betweeners may be further divided into two cohorts. In the first cohort are those who find the Ayurveda modalities useful, but do not subscribe to its fundamentals and philosophy. People do reverse pharmacology for new drug development, taking cues from ayurvedic classics. Pancakarma and ksarasfitra applications are used in intractable conditions. Prakrti analysis is carried out for possible personalized disease management propositions. Such individuals are actually progressive and liberated members of modern science, who consider that carefully chosen techniques of patient care in Ayurveda may be provided some sort of place in modern science. The second cohort of moderates are those who sense the deep philosophical and biological connotations behind the dictums of Ayurveda and hence warn that without understanding the ayurvedic science and its philosophy, its applications may be deleterious (Valiathan 2016).
To make a distinction between modern functional biology and the ayurvedic conceptualization of system functioning, a new term “Ayurvedic biology” was even proposed by such enlightened thinkers who stressed that Ayurveda should be understood within its own frame of knowledge without getting adulterated or diluted by any uncanny scientific idea (Valiathan 2006). However, the efforts of such moderates may go waste in contemporary times when evidence-based practice is a public policy requirement for both national healthcare systems and scientific research bodies (Patwardhan 2013). Evidence-based practice has found favor with the patient community as well, since with the rising levels of education, awareness and the ease of access to information through digital technologies, patients are able to make more informed decisions when evidence-based practices are implemented in healthcare delivery. For this reason, assembling evidence has become a crucial step for the further development of Ayurveda (Patwardhan 2014).
Assembling Evidence in Ayurveda
The practice of Ayurveda is guided by the dictum of unity and interconnectivity of microcosm and macrocosm (yat pindi tatha brahmaride). This dictum has led to distinct and unique methods of decision-making in Ayurveda. From an early stage in its development as a healthcare system, Ayurveda has emphasized the need for meticulous observations, experimentation and the uniquely peculiar method of challenge and re-challenge to improvise the theories through debates. Ayurvedic texts, in common with the canonical texts of Chinese medicine, are much more than pharmacopeias or formularies, since these textbooks assemble the evidence arising out of these observations, experimentations and debates.
With regard to evidence generation, Ayurveda utilizes its own unique system. It strives to generate “unquestionable knowledge”, i.e. evidence by distinctly distinguishing the sata (truth or existent) from asata (untruth or nonexistent). A useful aphorism in this context is the saying that the sata never ceases to exist, whereas asata never actually comes into existence, as enunciated in the Bhagavad Gita (Fosse 2007; Rastogi 2010). The methods employed for acquiring true knowledge are pratyaksa (direct evidence), anumana (indirect evidence), yukti (experimental evidence) and dpta (documented evidence).
Direct and Indirect Evidence
Duly acknowledging the limiting factors related to the means of gaining knowledge, and suggesting the ways to remove them in order to acquire absolute knowledge is akin to the idea of bias and errors of current research methodology. The ayurvedic proposition of factors limiting the procurement of knowledge is actually more pervasive than the idea of systemic and random errors alone (Figure 7.2). Science, however, has made fascinating progress in countering these limiting factors
FIGURE 7.2 Factors limiting knowledge gain.
related to the direct observations by devising appropriate technologies and obtaining a fair amount of reliable knowledge. Inferences of indirect observation are principally based upon the factual observations made in the past and finding a resemblance between past events and the happenings of the present. Indirect evidence, however, finds a much wider application in contemporary science and forms the basis of almost every imaging investigation done currently.
This is most fascinating of all research methods adopted in the past. Yukti begins with formulating a hypothesis about the disease in terms of its cause, presentation and prognosis and subsequently proposes a rational plan to manage it on the basis of the conceived hypothesis. Samprapti is the process of pathogenesis, where disease-related offensive and individual-related defensive mechanisms interact to generate a new biological entity - vikrti - which was nonexistent before this mutual interaction. The treatment proposition in Ayurveda essentially aims to dissociate the samprapti (sampraptivighatana) and hence to restore the pre-morbid state (Singh 2010b). A yukti hypothesis is like a superiority hypothesis testing where assumed treatment plan is hypothesized to be better than other treatment options on the basis of previous experiences or textual knowledge (Wang et al. 2017).
Āpta (Documented Evidence)
After assembling the knowledge from all resources and checking it for all possible errors, what remains is the absolute knowledge, called apta in Ayurveda. The concept of apta is uniquely described in Ayurveda as being knowledge (1) devoid of raja (bias) and tama (errors), and (2) which is internally as well as externally valid in reference to time (yisam trikalamamalam). Such knowledge may be considered highest on the evidence hierarchy and is proposed as vakyam asamsayam (undoubted statements) in Ayurveda. Caraka Samhita states that the strength of knowledge gathered through perseverance, by those who are devoid of raja and tama, is true beyond time and space (Tripathi 1983a).
Journeying through the Evidence in Ayurveda
A journey through the various disciplines of Ayurveda is an extraordinary and exemplary account of an evolutionary course taken to make it dynamic, versatile and applicable through the ages. In almost every single segment, ranging from diagnostics to treatment, drug procurement to drug processing and formulating, basic sciences and applied sciences, Ayurveda presents a glittering account of its diligent and meticulous efforts, applying the intuitive wisdom and deductive inferences generated through trial and error to reach its propositions recounted in various classics. While documenting such observations, Ayurveda seems to adhere strongly to the principles of ethics, which are very similar to the ethics of scientific writing, as known today. Caraka Samhita clearly states that it is the original work of Agnivesa redacted by Caraka and subsequently replenished by Drdhabala, which is the utmost example of adhering to the ethics of scientific writing (Tripathi 1983b). Similar publication honesty and ethics were followed by all subsequent treatises of Ayurveda which borrowed from the three big classics (Brhatrayi namely Caraka Samhita, Susruta Samhita and Astangahrdaya) with due acknowledgment and citations of the original work.
Evidence Pertaining to the Etiopathogenesis and Disease Presentation
Modern scientific medicine derives its scientific base almost entirely from randomized control trials, conditioned by the clarity of its output and arrived at in a relatively short time frame (rarely more than 5-10 years). The practitioners of modern medicine allege that Ayurveda cannot and does not measure up to this standard. This is wrong, for much of the evidence in Ayurveda actually comes from what may be described as self-styled longitudinal cohort studies passing through succeeding generations with the observations carried forward from one generation of investigators to another. The time span of these studies could be at least several decades, spanning up to a few hundred years. It is only with the evidence from such extremely long time span studies that one may arrive at the etiological description (hetu) of various diseases in Ayurveda. We see, surprisingly, that the кёш are not only generic in terms of causes, leading to the gross disequilibrium in various dosas, but are also specifically leading only to a particular set of disorders. Such an approach enabled ancient exponents of Ayurveda to unravel and discover the existence of multiple etiopathogenetic factors, despite the overall clinical manifestations being relatively similar and monotonous. Diabetes is a good example of the case. Being incriminated for disharmonic energy expenditure and intake for a large part of its history, now it is fairly understood that diabetes is a heterogeneous disease arriving from too many distinct pathways joining a common tract to make the distinct manifestations (Pietropaolo et al. 2007; Staimez et al. 2019). This is obvious to note that the treatment would not be effective unless it acts precisely at the path of its origin and this makes diabetes a difficult to cure condition with insufficient care, despite all the advancements made in its management (Rastogi
FIGURE 7.3 Heterogenic pathogenesis in diabetes and arc of action for its management.
2019). For a comprehensive management plan of diabetes, an arc of action would eventually be required, cutting across all the possible causes of the disease in a given case (Figure 7.3).
Another example of the success of the ayurvedic evidence gathering is the acknowledgment of phenotypic variations of pathology. Phenotypic variability in a disease with differential symptom dominance in different disease subpopulations is another recent realization in modern science, although it is defined exponentially in Ayurveda, in almost every single disease. A disease distinguishable into subtypes on the basis of precipitating dosa subsequently also defines the phenotypic variability of the disease by means of dominating clinical features. The diseases, therefore, can be of vata, pitta or kapha subtype, or their variable combinations or can be exogenous, where dosa disharmony arises subsequent to the initiation of the primary cause. Sandhivdta (osteoarthritis) which is a vata nanatmaja (caused by vata alone) disease is another good example of the case. Keeping vata alone as the major cause of the disease, it varies phenotypically owing to the primary pathology leading to vata imbalance. If it is due to an excess of kapha, it would present dhatvagni mandya (hypometabolic state) as a cause and would present as obese osteoarthritis. On the other hand, if it
FIGURE 7.4 Phenotype variability in osteoarthritis warranting a search for its cause.
is marked with pitta and vata predominance, it would present with dhatu ksaya (degenerative state) marked by emaciation (Figure 7.4). Phenotypical variability in osteoarthritis is recently recognized in modern healthcare, and a differential treatment plan is proposed to tackle such cases originating through different routes, despite their common clinical features (Deveza et al. 2017).