Paradoxical prosopagnosia in semantic dementia

Objective: To study episodic and semantic memory for faces and other non-verbal information in semantic dementia (SD). Background: Semantic memory impaired in the rare diagnosis of SD by definition, including knowledge about well- known persons and their appearance. Episodic memory is held to be better preserved. Methods: Two computerized face recognition tests were administered, one measuring episodic memory (Male Faces) and one semantic memory (Political Faces) in addition to a comprehensive test battery. A computerised test of non-verbal semantic memory for national symbols (Euro Flags) was also administered druring the retention interval of the Male Faces test. Results: The SD participants were severely impaired in the episodic face recognition test. In contrast, their performance was in the normal range in Euro Flags and Political Faces, based on knowledge of national political figures. Conclusion: The results are discussed in terms of preserved dynamic memory and severely impaired memory for static facial information in semantic dementia. Research proposals regarding further studies of this paradoxical prosopagnosia in semantic dementia are presented in order to clarify issues regarding static versus dynamic aspects of face memory.

Associations of cerebrospinal fluid amyloidogenic nanoplaques with cytokines in Alzheimer’s disease

Background:The aggregation of amyloidβ(Aβ)is central in the pathogenesis of Alzheimer’s disease(AD).Recently it has been shown that specifically,larger,Thioflavin T-binding Aβaggregates are associated with increased neuroinflammation and cytokine release.This study was aimed to quantify fibrillary amyloid aggregates,so-called nanoplaques,and investigate their relationship with cytokines in the cerebrospinal fluid(CSF).Methods:CSF was collected from 111 patients assessed for cognitive complaints at the Oslo University Hospital Memory Clinic.The patients were grouped based on their amyloid status.The CSF nanoplaque concentration was quantified with the Thioflavin T-fluorescence correlation spectroscopy(ThT-FCS)assay.The levels of nine cytokines(eotaxin-1,granulocyte stimulating factor,interleukin[IL]-6,IL-7,IL-8,monocyte chemoattractant protein-1,gammainduced protein 10,macrophage inflammatory protein[MIP]-1α,and MIP-1β)were quantified with a magnetic bead-based multiplex assay and read on a Luminex IS 200 instrument.Results:There were 49 amyloid-negative and 62 amyloid-positive patients in the cohort;none of the cytokines differed significantly between the amyloid groups.The increased nanoplaque levels were associated with levels of MIP-1βbelow the lower limit of quantification,and with decreased levels of MIP-1αand IL-8.The associations remained significant when adjusted for age,sex,cognitive function,apolipoproteinε4 status and CSF core biomarker levels.Conclusion:The cytokine levels were not associated with amyloid status in this cohort.The nanoplaque levels were negatively associated with MIP-1β,MIP-1αand IL-8,which is in line with recent findings suggesting that the upregulation of some cytokine markers has a protective role and is negatively associated with AD progression.