Naming and conceptual understanding in frontotemporal dementia

Abstract

Behavioural variant frontotemporal dementia (bvFTD) is characterised by behaviour change and impaired executive skills. There is growing evidence that naming difficulties may also be present but the basis for these is unclear. A primary semantic deficit has been proposed, although executive contributions to naming breakdown are also possible. The study aimed to improve understanding of the naming disorder in bvFTD through direct comparison with semantic dementia (SD), and examination of neural correlates. It aimed also to address current controversies about the role of the anterior temporal lobes in semantic memory. We studied 71 bvFTD and 32 SD patients. Naming data were elicited by two picture naming tests (one challenging and one less demanding) and word comprehension by word-picture matching. Structural magnetic resonance images were rated blind using a standardised visual rating scale. Around half of bvFTD patients showed impaired naming and 17% impaired word-picture matching. Deficits in bvFTD were less severe than in SD, but showed a similar pattern. There were strong inverse correlations between naming scores and atrophy in temporal structures, particularly temporal pole and fusiform gyrus. Word comprehension scores correlated more strongly with posterior than anterior temporal lobe atrophy in SD. Error analysis highlighted a significant relationship in both groups between associative-type responses and temporal pole atrophy. By contrast, ‘don't know’ responses, suggesting a loss of conceptual knowledge, correlated with more posterior temporal regions. There was some correlation in bvFTD between naming and executive test performance but not with frontal lobe atrophy. The findings support the view that naming problems can arise in bvFTD independently of patients' ‘frontal’ executive impairment and highlight clinical overlap between bvFTD and SD. We discuss the findings in relation to the hub and spoke model of semantic memory and argue against the notion of an anterior temporal lobe semantic hub.

When it is not primary progressive aphasia: A scoping review of spoken language impairment in other neurodegenerative dementias

“…Sixteen studies examined language impairment in bvFTD. Nine studies reported impairments in naming 49,[66][67][68][69][70][71][72] with four of these studies specifically identifying action naming as a deficit. 49,66,71,72 Other impairments included errors in word repetition, phonological errors, reduced speech output, verbal perseverations and echolalia, 69 and difficulties with organizing narratives 73 and with grammar.…”

Anomia is present pre-symptomatically in frontotemporal dementia due to MAPT mutations

“…These findings are consistent with previous studies which have identified different regions to be related to anomia according to the likely linguistic subdomain affecting naming ability. Whilst anterior temporal regions have been found to correlate with naming deficits when semantic impairment is present, such as in the semantic variant of PPA [ 9 , 10 , 23 ], frontal lobe regions may be involved when there is impairment of word generation and motor aspects of speech and language, such as in the non-fluent variant of PPA. These include the inferior frontal lobe, opercular and anterior insula [ 24 – 26 ], as was seen here in both GRN and C9orf72 mutation carriers.…”

“…Although mutations in any of these genes can lead to impaired naming ability (anomia), MAPT mutation carriers tend to show the most pronounced deficit with previous studies showing that such difficulties can even be detected before symptom onset [ 3 – 5 ]. Importantly, whilst anomia is one of the key manifestations of people with the language variant of FTD [ 6 ], a similar pattern of naming deficits, albeit often less severe, has been found in the early stages of people presenting with both behavioural and motor symptoms [ 7 – 9 ], suggesting that impairment could potentially be seen in all of the phenotypes of genetic FTD.…”

One-Year Analysis of Risk Factors Associated With Cognitive Impairment in Newly Diagnosed Epilepsy in Adults

“…After 1 y of anti-seizure medication treatment, picture-naming function improved in PWE with FLE in our study. Functional magnetic resonance imaging was used to locate the encephalic region and network connectivity responsible for naming, and temporal lobe was involved in it ( 39 , 40 ). It might be the pathological changes in the temporal lobe for PWE with TLE leading to no improvement in picture-naming function to anti-seizure medication treatment.…”