Abstract
According to the World Health Organization (WHO), dementia is a disorder that occurs as result of a neurodegenerative process in brain, and usually is chronic or progressive by nature. Most descriptions of senile dementia date back to Alois Alzheimer. In 1906, Alzheimer described the first patient, Auguste Deter, who suffered from the disorder that later became known as Alzheimer’s disease. Although, the history of the disease before 1906 is quite rich, little has been said about the contributions of ancient and medieval physicians to the understanding of dementia. Over the centuries, the concept of senile dementia changed from an inevitable mental decline with aging, to different sets of clinical features with narrow limits of diagnosis of a disease in its own right. Documentation of the historical origins of prevention, diagnosis, and therapies of dementia would make an important contribution to a more complete understanding of this pathological degeneration of dementia. The present review focuses on the contributions of Avicenna (AD 980–1037) to the development of diagnosis and the discovery of etiology of different forms of dementia, with the goal of revealing the extent to which dementia was understood in the golden age of Islam in Persia.
INTRODUCTION
According to the World Health Organization (WHO), dementia is a disorder that occurs as result of a neurodegenerative process in brain, and usually is chronic or progressive by nature. The disorder is associated with impairment of several functions, most notably in the cognitive domain, such as thinking, memory, calculation, learning, language, judgment, and comprehension [1]. Alzheimer’s disease (AD), dementia of Lewy bodies, vascular dementia, and frontotemporal dementia are the most common types in individuals older than 65 years [2, 3]; less common types include Parkinson’s disease, Creutzfeldt-Jakob disease, syphilis, and infectious dementia. Although the precise prevalence of dementia remains unknown worldwide, it is likely due to multifactorial causes which vary in their distribution around the world.
It is estimated that around 47 million individuals suffer from dementia, of whom nearly 60% live in low and middle-income countries, and the number is projected to double every two years. As the population of elderly is growing rapidly worldwide, the increase is becoming a significant global problem [2, 4]. With the rising prevalence of AD in the world [5, 6], and the absence of any definite cure, the necessity to turn back to the bases of modern medicine is one possibility. An important source of potentially new therapies for dementia may be hidden in the annals of historical medicine [7]. During the 8th to 13th centuries, the Islamic world underwent remarkable development in scientific, economic, and cultural works and later spread throughout Europe. Scholars from various parts of world with different cultural backgrounds were mandated to gather and translate previous initiatives taken by the ancient Egyptians, Greeks, and Persians in old Persia. The result was an impressive achievement in all aspects of science [8, 9]. Different schools of traditional medicine advocated different definitions and therapies for the diseases. Among the adherents to these traditions, Greek, Persian, Indian, and Chinese physicians made valuable contributions to the development of the discipline of medicine. Persian Medicine scholars such as Avicenna and Rhazes contributed greatly to the development of medical science [10, 11]. They added their own experiences to the concept of “humorism” that most observers ascribe to Hippocrates as early as 400 BCE [12]. Despite the great accomplishments with which Persian physicians enriched medicine, little has been documented about their findings. Avicenna’s masterpiece, the Canon of Medicine, was taught in European universities for centuries [13–15]. Reviewing the opinions of the scholars of yore may broaden the horizons of knowledge and the practice of medicine. Documenting the historical origins of prevention, diagnosis, and therapies of the disorder of dementia therefore, would be an important step forward. Although his book was issued centuries ago, his explanation of different types of dementia has never been linked with modern medicine’s concepts before. The current study focuses on the contributions of the most famous physician of the Golden Age of Islam, Avicenna, to the development of diagnosis and etiology of different forms of dementia and relation to modern medicine.
Abu Ali al-Husayn ibn’ Abd Allah ibn al-Hasan ibn Ali ibn Sina, Avicenna (980–1037 CE)
Ibn Sina (“son of Sina”), known as Avicenna (Fig. 1) in the West, was born on August 23, 980 CE in Afshaneh, a city of Persia [13, 17]. When he was five years old, the family moved to Bukhara [12, 18]. Ibn Sina memorized the Quran by the age of just eight. A greatly talented youth, Ibn Sina learned logic and mathematics and became well-versed in subjects such as astronomy, geometry, algebra, and theology already as a child [18–21]. Ibn Sina found the practice of medicine very appealing and started his professional work at the age of no more than 17. He was allowed by the Samanid governor, Nuh Ibn Mansour, to access the Royal Library of Bukhara in reward for Mansour’s medical treatment. The library had unique books and treaties of Greek physicians [22]. When Ibn Sina’s encyclopedia of medicine, Al-Qanun fi al-Tibb (The Canon of Medicine) (Fig. 2) first appeared, it overshadowed the medical books of the past. The encyclopedia was translated into Latin in the years 1114–1187 CE, and then to English, German, and French, and it remained one of the most important medical reference works in European universities before the 18th century [21, 24]. The book is divided into five volumes of which Book 3 includes discussions about a number of diseases related to the brain [25–27].
A portrait of Avicenna drawn by Somaiyeh Taheri on a picture of the page of Canon of Medicine which relates to the manuscript.
A piece of the Canon of Medicine by Avicenna reproduced with the permission of Yale University.
NESYAN IN CANON OF MEDICINE
From Avicenna’s point of view, brain disorders are divided into the three categories [25] to be discussed below: Fisad-al-zekr (corruption of short-term memory); Fisad-al-fekr (corruption of thinking); and Fisad-al-takhayol (corruption of imagination).
Definition and etiology
Fisad-al-Zekr
According to Avicenna, common symptoms of patients with fisad-al-zekr are their inability to recall what they learned in the past. The patients cannot precisely interpret what they have seen or heard, although the five main senses appear to be intact. Sometimes they cannot recollect recent events but are able to recall events in the more distant past. In terms of the ability to remember past and recent events, the patients tend to have more intact memory of remote events. In general, they have problems in recalling past events. Avicenna believed that healthy individuals who suffered from nesyan are more susceptible to stroke and epilepsy.
Avicenna in third volume of the Canon of Medicine Quotes: “Different brain damages are due to changes in brain temperament. In patients with Fisad-al-Zekr, sensation is intact and imagination of ghost and objects in dream and awareness are correct. In these patients, the form and shape of things seen in dream or in awareness cannot be interpreted and whatever they have seen or heard doesn’t remain in their minds and the recall will be impaired. In this case the injury is in the posterior part of the brain”.
Fisad-al-Fekr
Patients of this type are not capable of distinguishing between appropriate and inappropriate behaviors. For example, they express or desire something that is not suitable in the given situation. They also cannot explain properly what they have seen. Ibn Sina has described a patient of this type who had thrown carpets and kitchen utensils from the roof of the house. Although his understanding of the objects was correct, he was unable to realize that he should not throw them.
Fisad-al-Takhayol
According to the Canon of Medicine, the patients of this group have problems of dreaming and imagining. They dream rarely and if so, they forget the dreams rapidly. Sometimes they see or imagine something that is not real such as people, animal, fire, and water. Avicenna believed that it could be the consequence of atrophy. In the encyclopedia, the etiologies of these brain disorders were categorized into two groups according to whether the causes originate outside or inside the body. Those causes include external factors such as head trauma, and internal factors, such as ailments of the stomach or uterus, fevers, lung malfunction, or brain disease. Table 1 demonstrates the criteria for dementia in modern medicine and as described by Avicenna to indicate the differences and similarities of Avicenna’s translational approach.
Comparison of the criteria of three types of dementia in modern medicine and Canon of Medicine
Contributions of Avicenna to our understanding of neurological disease and terms
DISCUSSION
In the Golden Age of Islam, scholars had a fundamental role in development of the medical sciences. They described numerous medical concepts, the main parts of which were first raised in the post-renaissance times [18]. In addition, these scholars had novel theories of categorization, definition, and etiology of brain cognitive function impairment [26]. Although some of the categorizations and justifications of etiology cannot be explained by reference to the current medical concepts, many are close to modern definitions of dementia. As an outstanding figure of the golden age of Islamic scholarship, Ibn Sina was one of the most prominent scientists of his era and the Canon of Medicine was a comprehensive encyclopedia of acquired knowledge and documentation from physicians throughout history [10]. Most of his descriptions of the etiology of dementia were based on the theory of humors and cannot be interpreted by the modern medicine, but his definitions and classifications of memory dysfunction are similar to the different types of dementia. Ibn Sina described the definition and etiology of each type in details.
As in modern medicine, Avicenna categorized memory loss, and divided it into three distinct types: Inasmuch as the first classification of the disease was done by Avicenna centuries ago, he defined three different types of memory loss according to their etiology [28].
Intact primary sensation, normal insight of objects, memory impairment, and problems of recall were described by Avicenna as the presentation of fisad-al-zekr. The criteria are very similar to those of AD in allopathic medicine. Intact primary sensation accompanied by failure to recognize an object and agnosia were mentioned in Canon of Medicine ten centuries ago.
Fisad-al-Fekr is the second category of memory impairment explained by Avicenna. No memory impairment, inability to distinguish between wrong and right, thoughtlessness, inability to describe precisely what one sees and hears described by Avicenna, is compatible with disinhibition, socially inappropriate behavior, tactlessness, and disobeying socially accepted norms, associated with the criteria of frontotemporal dementia. This type of dementia was also explained by Avicenna [29, 30].
Avicenna categorized patients with problems of dreaming and imagining unreal objects, such as the ones who suffer from Fisad-al-Takhayol. It seems that this type of ailment is similar to the symptoms of dementia with Lewy bodies. Recurrent visual hallucinations and fluctuations of alertness are the common criteria for two medical disciplines, just as described by Avicenna in Canon of Medicine of a patient who imagined fire and unreal objects [31].
Head trauma, vitamin B12 deficiency, inflammation due to fever, and multi organ failure are the possible etiologies of dementia, all of which Avicenna had also mentioned in other terms. Obviously vitamin B12 was unknown at the time of Avicenna. He had explained gastrointestinal problems as probable etiologies of dementia. On the other hand, allopathic medicine has proved that vitamin B12 is readily absorbed in duodenum. It can be concluded that gastrointestinal problems such as impairment of vitamin B12 absorption is one of the etiologies of dementia.
In conclusion, it is important to acknowledge that Avicenna categorized different types of memory impairment centuries ago without access to modern diagnostic modalities such as imaging. We believe that modern medicine owes its advances to the accomplishments and contributions of predecessors such as Avicenna throughout the history.
CONFLICT OF INTEREST
Authors’ disclosures available online (https://www.j-alz.com/manuscript-disclosures/19-0345r1).