Semantic Dementia Research Paper

The motivation behind this paper was to fully explain Semantic Dementia in order to distinguish it from other similar disorders such as dementia of Alzheimer type (DAT), Progressive Aphasia, and Pick’s Disease. The signs, symptoms, and prognoses of Semantic Dementia were addressed in five patients. Semantic memory is long-term and contains information about objects, facts, concepts, and words and their meanings. Tasks that may be affected by semantic memory impairment include: naming, defining spoken words, word-picture and picture-picture matching, and exemplars on category fluency tests. Semantic Dementia is characterized by: (i) selective impairment of semantic memory; (ii) relative sparing of comprehension, syntax, and phonology; (iii)

normal perceptual skills and non-verbal problem-solving abilities; (iv) preserved autobiographical and episodic memory; and (v) a reading disorder with a pattern of surface dyslexia (Hodges, Patterson, Oxbury, & Funnell, 1992).
The study examined five patients between the ages of forty-two and sixty-eight years old who had either atrophy, hypometabolism, or hypoperfusion affecting their temporal lobe(s). They all had anomia and difficulty naming people, places, or things. Nearly all five patients had impaired vocabulary comprehension of nominal terms. Other impairments experienced by two or more patients included: recognizing people, semantic paraphasias, alexia, coarticulation problems, regularized pronunciations of irregular words, poor spelling, identifying animals or objects as real, and change in personality.
Impairments of verbal and performance IQ were most apparent on vocabulary, information, and similarities. Three of the patients most affected by the syndrome had difficulty on picture completion. All five patients performed within the normal range on autobiographical episodic memory, facial recognition, and letter-based verbal fluency tests. However, they were all below average on verbal memory, verbal fluency categories, lexico-semantic memory, and personal semantic memory tests.
Neuropsychological test on semantic memory and visual semantic knowledge were done on the patients. On the semantic memory test battery, all five patients were severely impaired in naming and category fluency, but scored average on the picture sorting test. Semantic comprehension was proved to be impaired by the test of picture pointing in response to spoken word. Only three patients were tested for visual semantic knowledge, using non-verbal semantic memory tests and they scored below average for classifying items as real or unreal, match conceptually related pictures, and identify famous personalities.
Semantic Dementia consists of semantic deterioration which disrupts language, factual memory and knowledge, and object recognition. A loss of vocabulary is one of the main symptoms, along with preservation of syntax, phonology, and autobiographical and practical episodic memory. Word knowledge, notably information, similarities, and vocabulary were some of the most profound impairments, according to the data from the verbal subtests.
In nearly all cases of semantic dementia, there was damage to the left anterior temporal lobe, left temporal regions, or left temporo-parietal regions. This led Hodges et al. to conclude that semantic dementia results from excessive temporal neocortical damage (Hodges et al., 1992). The findings implicate that Semantic Dementia is not the same as DAT, Progressive Aphasia, and Pick’s Disease (though Semantic Dementia can sometimes lead to Pick’s disease).