has been used as a primary diagnostic technique for discerning how SD patients understand word meaning.Speech of SD patients is marked by word-finding pauses, reduced frequency of content words, semantic paraphasias, circumlocutions, increased ratios of verbs to nouns, increased numbers of adverbs, and multiple repeats.SD patients sometimes show symptoms of surface dyslexia, a relatively selective impairment in reading low-frequency words with exceptional or atypical spelling-to-sound correspondences.It is currently unknown why semantic memory is impaired and semantic knowledge deteriorates in SD patients, though the cause may be due to damage to an amodal semantic system. This theory is supported by the atrophy of the anterior temporal lobe, which is believed to contain a component of the semantic system that integrates conceptual information. Others hypothesize that the damage is predominantly to the ventral temporal cortex, since SD patients remember numbers and music, but have trouble associating visual cues to concrete words.Due to the variety of symptoms dementia patients present, it becomes more difficult to assess semantic memory capability especially with regard to musical elements. In order to circumvent the explicit verbal learning tests for dementia, semantic melodic matching is a useful technique for detecting the semantic memory of semantic dementia patients. Moreover, it is important to maintain that these tests must be compared to nonmusical domain tests, as music cognition is not often measured in semantic dementia patients (less data available).
Based on the data of imaging studies that looked at the localization of processing melodies, it can be inferred that the anatomical location of the processes in consistent with the findings that some SD patients have intact melody recognition. Additionally, the neurobiological basis for musical emotion identification implicated the limbic and paralimbic structures in this process. Overall, the results of these studies suggest that the neurobiological basis of musical semantic memory is bilaterally located in the cerebral hemispheres, likely around the fronto-temporal areas of the brain. Unfortunately, due to the lack of studies studying musical semantic memory, conclusions cannot be more specific. Treatment
There is currently no known curative treatment for SD. The average duration of illness is 8–10 years, and its progression cannot be slowed. Progression of SD can lead to behavioral and social difficulties, thus supportive care is essential for improving quality of life in SD patients as they grow more incomprehensible. Continuous practice in lexical learning has been shown to improve semantic memory in SD patients. No preventative measures for SD are recognized. References
Reference 20: Rohani Omar, Julia C. Halistone, and Jason D. Warren, "Semantic Memory for Music in Dementia," Music Perception 29, no. 5 (June 2012):, doi:10.1525/mp.2012.29.5.467.Reference 21:Lise Gagnon, Isabelle Peretz, and Tamàs Fülöp, "Musical structural determinants of emotional judgments in dementia of the Alzheimer type.," Neuropsychology 23, no. 1 (2009): doi:10.1037/a0013790.Reference 22: J. C. Hailstone, R. Omar, and J. D. Warren, "Relatively preserved knowledge of music in semantic dementia," Journal of Neurology, Neurosurgery & Psychiatry 80, no. 7 (2009): doi:10.1136/jnnp.2008.153130.