Cognitive reserve attenuates age-related cognitive decline in the context of putatively accelerated brain ageing in schizophrenia-spectrum disorders

Abstract

BackgroundIn schizophrenia, relative stability in the magnitude of cognitive deficits across age and illness duration is inconsistent with the evidence of accelerated deterioration in brain regions known to support these functions. These discrepant brain–cognition outcomes may be explained by variability in cognitive reserve (CR), which in neurological disorders has been shown to buffer against brain pathology and minimize its impact on cognitive or clinical indicators of illness.MethodsAge-related change in fluid reasoning, working memory and frontal brain volume, area and thickness were mapped using regression analysis in 214 individuals with schizophrenia or schizoaffective disorder and 168 healthy controls. In patients, these changes were modelled as a function of CR.ResultsPatients showed exaggerated age-related decline in brain structure, but not fluid reasoning compared to controls. In the patient group, no moderation of age-related brain structural change by CR was evident. However, age-related cognitive change was moderated by CR, such that only patients with low CR showed evidence of exaggerated fluid reasoning decline that paralleled the exaggerated age-related deterioration of underpinning brain structures seen in all patients.ConclusionsIn schizophrenia-spectrum illness, CR may negate ageing effects on fluid reasoning by buffering against pathologically exaggerated structural brain deterioration through some form of compensation. CR may represent an important modifier that could explain inconsistencies in brain structure – cognition outcomes in the extant literature.

Cognitive reserve in stroke patients

“…CR is a neuroprotective agent to buffer cognitive decline and promotes recovery regardless of the degree of traumatic brain injury involved (Steward et al, 2018). Low CR was associated with a decline in fluid reasoning skills, as seen in people with schizophrenia spectrum disorder (Van Rheenen et al, 2019). Such patients need intensive training to buffer from cognitive impairment (Buonocore et al, 2018).…”

Role of cognitive reserve in cognitive variability in euthymic individuals with bipolar disorder: cross-sectional cluster analysis

“…Cognitive reserve was estimated for each participant through a composite score of three proxy measures: years of education and the two intelligence indices, the TOPF and the Vocabulary subtest of the WASI-II, according to previous recommendations. 15 , 16 Using a factor analysis, a single score was derived from these three variables for each participant. 15 This factor score accounted for 59.8% of the shared variance in the three variables and was used as a measure of cognitive reserve in all subsequent analyses.…”

“… 14 The concept of reserve has been extensively explored in neurological and psychiatric disorders such as dementia, multiple sclerosis and schizophrenia, representing individual differences in the capacity to compensate for age- and illness-related cognitive decline in the presence of neuropathology. 14 – 16 Previous research in bipolar disorder suggests an association of cognitive reserve with cognitive performance, 17 but this has not been explored in the context of cognitive heterogeneity, particularly whether and to what extent cognitive differences between putative subgroups can be explained as a function of cognitive reserve.…”

Test–retest reliability and convergent validity of the test of nonverbal intelligence-fourth edition in patients with schizophrenia

“…Fluid intelligence is a critical cognitive ability affecting a wide variety of daily activities [5,6]. Fluid intelligence deficits are common in patients with schizophrenia, and these deficits are often associated with cognitive impairment in this group [7][8][9][10][11][12]. The deficits of fluid intelligence in patients with schizophrenia are associated with difficulties in daily independent functioning [10,11,13].…”