Historical Perspective

The diagnosis and understanding of neurocognitive disorders have evolved significantly over time. Descriptions of cognitive decline resembling neurocognitive disorders can be found in ancient civilizations; however, the concept of neurocognitive disorders as a distinct medical condition was not well-defined during this period. It wasn’t until the early 19th century, that the term “senile dementia” was coined by French physician Jean Étienne Dominique Esquirol. He recognized that older individuals could experience progressive cognitive decline without an apparent cause. This marked the first attempt to classify dementia as a distinct disorder (Vatanabe, Manzine, & Cominetti, 2020).

In the early 1900s, German psychiatrist Alois Alzheimer observed a patient named Auguste Deter with severe memory loss, language difficulties, and behavioral changes. After Deter’s death, Alzheimer examined her brain and discovered neurofibrillary tangles and plaques, which are characteristic pathological features of what became known as Alzheimer’s disease. Over the course of the 20th century, researchers began to distinguish different subtypes of dementia. They recognized that Alzheimer’s disease was the most common cause, but other forms like vascular dementia were also identified (Vatanabe, Manzine, & Cominetti, 2020).

The Diagnostic and Statistical Manual of Mental Disorders (DSM), published by the American Psychiatric Association, has described neurocognitive-type disorders which have evolved over time as more was understood about the conditions. The first edition of the DSM did not include specific diagnostic criteria for dementia. It classified cognitive disorders under the broad category of “Organic Brain Syndromes” without detailed subcategories. The second edition of the DSM introduced the term “Senile Dementia” and included a separate category for it however, the diagnostic criteria were relatively vague and did not provide a comprehensive framework for diagnosing or classifying different types of dementia (Vatanabe, Manzine, & Cominetti, 2020).

The third edition of the DSM brought significant changes to the classification of dementia. It introduced more specific diagnostic criteria and listed dementia as a distinct disorder under the category of “Organic Mental Disorders.” This edition emphasized the importance of cognitive impairment and functional decline in the diagnosis of dementia. These criteria provided a standardized framework for diagnosing dementia and distinguishing it from other mental disorders. The revised third edition of the DSM made some refinements to the diagnostic criteria for dementia. It introduced the term “Dementia of the Alzheimer’s Type” as a specific subtype and included additional subtypes such as vascular dementia and dementia due to other medical conditions (Vatanabe, Manzine, & Cominetti, 2020).

The fourth edition of the DSM further expanded the classification of dementia. It introduced a more detailed and comprehensive framework for diagnosing different types of dementia. This edition included specific criteria for Alzheimer’s disease, vascular dementia, dementia due to other medical conditions, substance-induced dementia, and dementia not otherwise specified (Vatanabe, Manzine, & Cominetti, 2020).

The fifth edition of the DSM brought further revisions to the diagnostic criteria for neurocognitive disorders, replacing the term “dementia.” It introduced the category of “Neurocognitive Disorders.” This edition emphasized a continuum of cognitive impairment, ranging from mild to major, and incorporated changes in criteria for specific disorders like Alzheimer’s disease and frontotemporal neurocognitive disorder. The DSM is periodically updated to reflect advances in research and understanding. The changes in the diagnostic criteria have aimed to improve accuracy, reliability, and consistency in the diagnosis of dementia and related neurocognitive disorders (Vatanabe, Manzine, & Cominetti, 2020).

A factor in the evolution of diagnostic criteria in the DSM was the development of neuroimaging techniques. Magnetic resonance imaging (MRI) and positron emission tomography (PET) allowed researchers to visualize brain changes associated with neurocognitive disorders. These imaging technologies have contributed to the understanding of different subtypes and improved diagnostic accuracy. In 2011, the National Institute on Aging and the Alzheimer’s Association published new diagnostic guidelines, emphasizing the importance of biomarkers and the preclinical stage of Alzheimer’s disease (Vatanabe, Manzine, & Cominetti, 2020).

Presently, there is a growing emphasis on early detection and prevention of dementia. Efforts are underway to identify biomarkers and develop interventions to delay the onset or slow the progression of cognitive decline. Understanding and diagnosis of neurocognitive disorders are still evolving, and ongoing research continues to refine our knowledge (Vatanabe, Manzine, & Cominetti, 2020).