IQ Subtypes in Schizophrenia

Abstract

Intellectual decline, a key component of cognitive impairment in schizophrenia, varies considerably across individuals. To examine such cognitive heterogeneity, we applied cluster analysis of IQ and oral reading scores in 73 patients with schizophrenia. The following 3 empirically-derived subtypes emerged: intellectually compromised (42%) with similarly subaverage IQ (M = 79.90) and oral reading (M = 84.03); intellectually deteriorated (29%) with subaverage IQ (M = 86.81) but average oral reading (M = 107.71); and intellectually preserved (29%) with average IQ (M = 108.38) and oral reading (M = 104.43). Compromised and deteriorated clusters showed impairments in both executive function and memory, whereas the preserved cluster showed only reduced executive functioning. The 3 clusters also differed in symptom patterns; with intellectually compromised and intellectually deteriorated both rated with higher negative than positive symptoms, in contrast to the opposite pattern of intellectually preserved. Cluster symptom and neuropsychological profiles may help to validate empirically-derived IQ subtypes in schizophrenia.

Exploring Heterogeneity on the Wisconsin Card Sorting Test in Schizophrenia Spectrum Disorders: A Cluster Analytical Investigation

“…While mixed reports have been published regarding the clinical significance of cognitive subgroups (Dawes et al, 2011;Geisler et al, 2015), the severely impaired subgroup in this instance was detected to exhibit greater negative symptomology compared to the moderate impairment and relatively intact subgroups. This is in line with several studies which suggest that individuals with SSD classified as having compromised cognitive capacity also experience more severe negative symptomology (Cobia et al, 2011;Potter & Nestor, 2010;Van Rheenen et al, 2018;Weinberg et al, 2016). However, as with previous research subgroups did not significantly differ in positive or affective symptom severity, suggesting that the cognitive subgroups identified in the current study do not reflect distinct clinical profiles, rather distinct executive phenotypes.…”

“…To date, investigations using cluster analytical techniques to characterise the cognitive heterogeneity within the schizophrenia spectrum have typically employed multidimensional batteries of cognition, with some studies entering indices of EF into the subgrouping analysis among other non-executive measures (Cobia et al, 2011;Dawes et al, 2011;Hill et al, 2002;Liu et al, 2011;Sauvé et al, 2018;Van Rheenen et al, 2017). When emergent subgroups are compared on select EF indices, meaningful differences are reported for some (Cobia et al, 2011;Gilbert et al, 2014;Liu et al, 2011;Van Rheenen et al, 2017), however not all subgroup comparisons (McDermid Vaz & Heinrichs, 2006;Potter & Nestor, 2010).…”

Neurocognitive heterogeneity across the spectrum of psychopathology: need for improved approaches to deficit detection and intervention

“…The cluster analysis approach has been successfully utilized in adults (13 studies) to detect neurocognitively homogenous subgroups in psychiatric disorders. Studies have examined neurocognitive clusters within specific disorders (i.e., schizophrenia, bipolar disorder, and gambling disorder) [27][28][29][30][31] or more commonly, across psychiatric disorders, such as examining across affective disorders, 32 across psychotic disorders, [33][34][35] and across the affect-psychosis spectrum. [36][37][38][39] The majority of studies identified three to four neurocognitive clusters, including a neurocognitively intact cluster and a globally impaired cluster.…”

“…Some degree of variability in the affected domain was noted across studies due to the range of assessed neurocognitive domains, although visual memory deficits, psychomotor speed deficits, and executive deficits were specifically identified. Importantly, these distinct subgroups were associated with critical clinical/functional variables, in that generally the more impaired clusters were associated to worse outcomes/variables, such as symptomology, 27,31,32,35,[40][41][42][43] psychiatric episodes, 30,34 and response to clinical treatment 28 as well as years of education, 32,34 age, 31,34 employment status, 30,31 community functioning, 33 and socioeconomic status. 32…”

Towards Therapeutic Applications of Arthropod VenomK+-Channel Blockers in CNS Neurologic Diseases Involving Memory Acquisition and Storage

“…Weickert et al [142] found that 51% of 117 patients with schizophrenia and decline in intelligence quotient (IQ) also exhibited deficits of executive function, memory, and attention. Deficits of executive function and memory also were found in 71% of 73 individuals with schizophrenia that showed intellectually compromised or deteriorated [143]. …”