The Japanese journal of neuropsychology

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ArticleTitle	Symptoms and classification of right-dominant semantic dementia
Language	J
AuthorList	Mamoru Hashimoto¹⁾, Naoko Ichimi²⁾, Naoko Tsunoda³⁾, Shizuka Sakuta¹⁾
Affiliation	¹⁾Department of Neuropsychiatry, Kindai University Faculty of Medicine ²⁾Department of Medical Quality and Safety Management, Kumamoto University Hospital ³⁾Mitsugumachi Memory Clinic
Publication	Japanese Journal of Neuropsychology: 40 (3), 177-186, 2024
Received
Accepted
Abstract	This review discussed the symptoms and classification of right-dominant semantic dementia (R-SD) from a symptomatological perspective. Brain functions related to visual semantic knowledge including face recognition, and social cognition such as emotional recognition, are localized in the right temporal lobe. On the other hand, cognitive functions related to verbal semantic knowledge are localized in the left temporal lobe. In R-SD, loss of visual semantic knowledge such as prosopagnosia and behavioral disorder including lack of empathy precede, followed by loss of verbal semantic knowledge. Conversely, L-SD is preceded by semantic variant primary progressive aphasia, followed by the appearance of loss of visual semantic knowledge and behavioral disorder. The difference in initial symptoms between R-SD and L-SD can be considered to reflect functional differences between the right and left temporal lobes. Therefore, rather than classifying R-SD and L-SD as different disorders, they should be univocally classified as temporal lobe variant FTD with semantic memory loss and behavioral disorder as the main symptoms.
Keywords	semantic dementia, right dominant SD, loss of semantic knowledge, behavioral disorder