The following is a summary of “Losing the chain of thought: A meta-analysis of functional neuroimaging studies using verbal tasks in schizophrenia,” published in the November 2023 issue of Neurology by Pilon et al.

Schizophrenia features disorganization symptoms encompassing illogical thinking, incoherent speech, tangentiality, and loose associations, often associated with language deficits. Understanding the neural underpinnings of these symptoms, numerous functional neuroimaging studies have investigated verbal tasks in schizophrenia. However, the outcomes across these studies have displayed heterogeneous findings. Consequently, a meta-analysis was conducted, drawing from 33 eligible functional neuroimaging studies retrieved through a systematic search of the Web of Sciences, PubMed, and EMBASE databases. These studies focused on verbal tasks such as verbal fluency and semantic processing in individuals with schizophrenia. The aim was to unravel the most consistent neural alterations observed during such tasks in individuals diagnosed with schizophrenia.

The meta-analysis utilizing the activation likelihood estimation (ALE) approach identified key neural alterations during verbal tasks in schizophrenia. Hyperactivations were evident in the left inferior frontal gyrus (IFG) and middle frontal gyrus (MFG), while hypoactivations were noted in the right IFG, precentral gyrus, and left caudate nucleus. Further analysis combining hyper and hypoactivations revealed altered activations in multiple brain regions. Notably, beyond classic language-associated areas, aberrant activations occurred in brain regions linked to executive functions, autobiographical memory, and, unexpectedly, motor functions. This suggests a broader neural network involvement beyond language processing deficits in schizophrenia. Intriguingly, the study emphasizes the need for further investigations focusing on the role of the striatum in linguistic sequencing among individuals with schizophrenia. Such future research could shed light on the intricate neural mechanisms underlying language deficits and disorganization symptoms in schizophrenia.

Source: sciencedirect.com/science/article/abs/pii/S0022395623005228