What happens to semantic memory when formal thought disorder remits? Revisiting a case study

Abstract

Improvement in FTD in schizophrenia was accompanied by a better and more stable semantic memory performance in TC. The findings are consistent with, and expand upon the original suggestion that thought disorder reflects disorganised access to semantic memory.

Assessing the Relationship between Semantic Processing and Thought Disorder Symptoms in Schizophrenia

“…This also confirms a negative relationship between TD severity and SM task performance, which fits with reports that SM performance is worse in patients with diagnostic TD (Goldberg et al, 1998;Tan & Rossell, 2014). It also supports evidence that greater TD severity is associated with exacerbated SM deficits (Leeson et al, 2005). It is important to re-iterate that the analyses here were correlational so no causal conclusions can be drawn.…”

“…While the nature of the relationship cannot be established here, it is plausible that these two aspects may be linked by poor regulation of appropriate responses. This aligns with findings that TD is associated with a degree of stable underlying neurocognitive impairments outside the acute TD stage (Subotnik et al, 2006), and that semantic deficits do not completely remit outside of the acute TD state (Leeson et al, 2005). Such patients have markedly more severe TD symptoms as evidenced by diagnostic criteria (Andreasen, 1986).…”

“…Some support for a semantic store problem has emerged using verbal fluency tasks, for example, category naming. Improvements in semantic functioning have also been observed when TD symptoms remit (Leeson, McKenna, Murray, Kondel, & Laws, 2005), which does not support the notion of a degraded semantic network and instead suggests that overactivation/access problems are more likely involved. The reduction is thought to be the result of words being poorly hierarchically organized, or no longer available.…”

A systematic review of task-based functional neuroimaging studies investigating language, semantic and executive processes in thought disorder

“…Such behaviour could be broadly consistent with notions of increased spreading of semantic activation (Spitzer, 1997), as well as semantic preoccupation (Chaika, 1974), though they do not substantially test these interpretations. Regardless, a propensity for the inappropriate verification of false semantic relationships has been documented in individuals with TD elsewhere (Leeson et al, 2005a). Moreover, the corresponding pattern of activation reported by Assaf et al (2006) suggests that TD could involve both an increased tendency for semantic-related anterior cingulate activation, and a failure to modulate this activation when such semantic processing is inappropriate.…”

A systematic review of the structural neuroimaging correlates of thought disorder

“…Yet, there has been evidence to suggest that degraded semantic storage may also play a role in TD (Leeson et al, 2005a;Rossell and David, 2006). Another proposal was that there is disorganisation within the semantic system, which may better account for residual deficits after the remission of TD (Leeson et al, 2005b). Whilst Oh et al (2002) identified semantic speech errors in the expressive speech of those with TD that were consistent with problematic lexical-semantic processes, they also argued that individuals with TD show separate difficulties in constructing global semantic themes to guide discourse.…”