Semantic dementia

Clinic

• SD also known as semantic variant primary progressive aphasia (svPPA),
• It is a progressive neurodegenerative disorder characterized by loss of semantic memory in both the verbal and non-verbal domains.
• The most common presenting symptoms are in the verbal domain (with loss of word meaning).
• Semantic dementia is a disorder of semantic memory that causes patients to lose the ability to match words or images to their meanings. However, it is fairly rare for patients with semantic dementia to develop category specific impairments, though there have been documented cases of it occurring. Typically, a more generalized semantic impairment results from dimmed semantic representations in the brain.

• SD is one of the three subtypes of frontotemporal lobar degeneration (FTLD).

• SD is a clinically defined syndrome but is associated with predominantly temporal lobe atrophy (left greater than right) and hence is sometimes called temporal variant FTLD (tvFTLD).
• SD is one of the three variants of primary progressive aphasia (PPA), which results from neurodegenerative disorders such as FTLD or Alzheimer's disease.

Semantic dementia vs Alzheimer

• Alzheimer's disease is affecting mainly episodic memory, defined as the memory related to specific, personal events distinct for each individual.
• Semantic dementia generally affects semantic memory, which refers to long-term memory that deals with common knowledge and facts.

Presentation

The defining characteristic of SD is decreased performance on tasks that require semantic memory. This includes

• Difficulty with naming pictures and objects
• Single word comprehension
• Categorizing, and knowing uses and features of objects
• Spontaneous speech creation, using words such as "this" or "things" where more specific and meaningful words can be used.
• Syntax is spared, and SD patients have the ability to discern syntactic violations and comprehend sentences with minimal lexical demands.
• SD patients have selectively worse concrete word knowledge and association, but retain knowledge and understanding of abstract words.
• SD patients are able to retain knowledge of numbers and music, but have more difficulty with concrete concepts with visual associations.
• Impairments of processing of phonemic structure and prosodic predictability have also been observed.

Semantic dementia Black-box

	Entities	miasms	remedies
	Apahasia Cognition impaired Dementia	BKV / JCV JE