Dementiaa



IntrodWhat is Dementia ?uction

Dementia is an organic brain syndrome which results in global cognitive impairments. Dementia can
occur as a result of a variety of neurological diseases. Some of the more well known dementing diseases
include Alzheimer’s disease (AD), multi-infarct dementia (MID), and Huntington’s disease (HD).
Throughout this essay the emphasis will be placed on AD (also known as dementia of the Alzheimer’s type,
and primary degenerative dementia), because statistically it is the most significant dementing disease
occurring in over 50% of demented patients (see epidemiology).

The clinical picture in dementia is very similar to delirium, except for the course. Delirium is an acute
transitory disorder. By contrast Dementia is a long term progressive disorder (with the exception of the
reversible dementias). The course of AD can range anywhere from 1.5 to 15 years with an average of
about 8.1 years (Terry , 1988). AD is usually divided into three stages mild, moderate, and severe.
Throughout these stages a specific sequence of cognitive deterioration is observed (Lezak, 1993). The mild
stage begins with memory, attention, speed dependent activities, and abstract reasoning dysfunction. Also
mild language impairments begin to surface. In the moderate stage, language deficits such as aphasia and
apraxia become prominent. Dysfluency, paraphasias, and bizzare word combinations are common midstage
speech defects. In the severe stage the patient is gradually reduced to a vegetative state. Speech becomes
nonfluent, repetitive, and largely non-communicative. Auditory comprehension is exceedingly limited, with
many patients displaying partial or complete mutism. Late in the course of the disease many
neuropsychological functions can no longer be measured. Also primitive reflexes such as grasp and suck
emerge. Death usually results from a disease such as pneumonia which overwhelms the limited vegetative
functions of the patient.
According to the Encyclopedia of Neuroscience dementia is defined as a “…sustained, multidimensional

loss of cognitive function secondary to organic central nervous system damage, unaccompanied by evidence

of an acute superimposed state of clouded consciousness as occurs with delirium or reduced arousal.”

Dementia is not a disease but rather a symptom of many conditions causing brain dysfunction. It arises as

a result of severe and diffuse brain damage. The essential feature of dementia is an intellectual decline

resulting from a progressive deterioration in brain functioning.

Dementia can occur as a result of a variety of neurological diseases. These include: Alzheimer’s disease

(dementia of the Alzheimer type), cerebrovascular disease in particular Multi-infract dementia (vascular

dementia), alcohol related diseases such as Marchiafava-Bignami disease (alcoholic dementia), AIDS (AIDS

dementia complex), Creutzfeldt-Jakob disease (myoclonic dementia), Pick’s disease, Huntington’s disease,

Parkinson’s disease, normal pressure hydrocephalus (NPH), and progressive supranuclear palsy (PSP).


Dementia is commonly differentiated along two dimensions: age and cortical level. The first dimension,

age, distinguishes between senile and presenile dementia. Senile dementia is used to describe patients

who become demented after the age of 65, whereas presenile dementia applies to patients who become


demented prior to that age. Late onset AD (LOAD)Alzheimer’s disease also known as senile dementia Alzheimer’s

type
(SDAT) is the predominant cause of senile dementia. Early onset AD (EOAD)lzheimer’s disease is the most

frequent cause of
presenile dementia,; but HDuntington’s disease, Pick’s disease and Creutzfeldt-Jakob

disease though not as frequent are also
important causes in presenile dementia.

The second dimension,

cortical level, differentiates between cortical and subcortical dementia. Cortical

dementia is used to

describe dementia which results from brain lesions at the cortical level, whereas

subcortical dementia

describes dementia resulting from subcortical brain lesions. ADlzheimer’s disease (AD) and Pick’s disease

are

the best known examples of cortical dementia; whereas HD, Parkinson’s disease (PD),ntia; while Huntington’s disease (HD), Parkinson’s disease

(PD), and progressive

supranuclear palsy (PSP)PSP are good examples of subcortical dementia (Mayke, 1994). Dementia with both

cortical and subcortical

features is also possible, in that case the term mixed dementia is used. Multi-infract dementiaID is a

common

example of mixed dementia.

Historical developments in dementia

Pre-Modern Developments

The use of the term dementia dates back to Roman times. “The Latin word dementia, derived from the Latin demens , did not originally

have the specific connotation

that it does today. It meant ‘being out of one’s mind’ and, as such, was a

general term for insanity or

insanitymadness (Pitt, 1987).” It was the encylopedist Celsus who first used the word

dementia in his “De re medicina”,,

published around AD 30. A century