Defining Dementia
The word dementia comes from the Latin demens meaning 'without a mind'. References to dementia can be found in Roman medical texts and in the philosophical works of Cicero. The term dementia came into common usage from the 18th Century when it had both clinical and legal connotations. Dementia implied a lack of competence and an inability to manage one's own affairs. In the French Revolution dementia became enshrined in law through Article 10 of the Napoleonic Code 1808:
'There is no crime when the accused is in a state of dementia at the time of the alleged act'.
Medical use of the term dementia evolved throughout the 19th century and was used to describe people whose mental disabilities were secondary to acquired brain damage, usually degenerative and often associated with old age. In this way dementia was distinguished from other forms mental disorder such as depression or schizophrenia. Loss of intellectual functioning was identified as being a pivotal aspect in the definition of dementia.
From the 20th century onwards scientific knowledge was supplemented through the examination of the brain and brain tissue. The brains of people who had died with a diagnosis of dementia were examined and compared to 'normal' and non demented people. Marce, in 1863, first described the shrinkage (cortical atrophy) present, the enlarged ventricles and 'softening' of the brain.
In 1907 Alois Alzheimer identified the senile plaques and neurofibrillary tangles that are common to the brains of people with Alzheimer's type dementia.
Current definition of dementia
Definitions of dementia have become more precise in the last twenty or so years. Currently the diagnostic criteria for dementia refers to the multiple cognitive and intellectual deficiencies and decline involving memory, new and previously learnt information and problems with language, impairment of motor skills, inability to recognize familiar people or objects and impairments in planning, organizing and abstract reasoning.
Current definition of Alzheimer's disease
Currently there are two main sets of diagnostic criteria that are used by the medical profession and psychologists to define a diagnosis of Alzheimer's disease:
Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV-TR) and
The National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorder Association (NINDS-ADRDA).
