Abstract
BackgroundIndividuals at ultra-high risk for psychosis (UHR) present with subtle alterations in cerebral white matter (WM), which appear to be associated with clinical and functional outcome. The effect of cognitive remediation on WM organization in UHR individuals has not been investigated previously.MethodsIn a randomized, clinical trial, UHR individuals aged 18 to 40 years were assigned to treatment as usual (TAU) or TAU plus cognitive remediation for 20 weeks. Cognitive remediation comprised 20 x 2-h sessions of neurocognitive and social-cognitive training. Primary outcome was whole brain fractional anisotropy derived from diffusion weighted imaging, statistically tested as an interaction between timepoint and treatment group. Secondary outcomes were restricted to five predefined region of interest (ROI) analyses on fractional anisotropy, axial diffusivity, radial diffusivity and mean diffusivity. For significant timepoint and treatment group interactions within these five ROIs, we explored associations between longitudinal changes in WM and cognitive functions/clinical symptoms. Finally, we explored dose-response effects of cognitive remediation on WM.ResultsA total of 111 UHR individuals were included. Attrition-rate was 26%. The cognitive remediation group completed on average 12 h of neurocognitive training, which was considerably lower than per protocol. We found no effect of cognitive remediation on whole-brain FA when compared to treatment as usual. Secondary ROI analyses revealed a nominal significant interaction between timepoint*treatment of AD in left medial lemniscus (P=0.016) which did not survive control for multiple comparisons. The exploratory test showed that this change in AD correlated to improvements of mental flexibility in the cognitive remediation group (p=0.001). We found no dose-response effect of neurocognitive training on WM.ConclusionsCognitive remediation comprising 12 h of neurocognitive training on average did not improve global or regional WM organization in UHR individuals. Further investigations of duration and intensity of cognitive training as necessary prerequisites of neuroplasticity-based changes are warranted.Clinical Trial RegistrationClinicalTrials.gov, identifier NCT02098408.
Highlights
Individuals at ultra-high risk (UHR) for psychosis present with cognitive impairments [1], intermediate between the marked cognitive deficits observed in patients with manifest psychotic disorders, and unaffected healthy controls [2,3,4]
At a whole-brain level, we identified an association between globally higher fractional anisotropy with a pattern of better cognitive functions in UHR individuals, but not in healthy controls
We identified cognitive functions associated with regional white matter (WM)-interaction in five regions when comparing UHR individuals to healthy controls
Summary
Individuals at ultra-high risk (UHR) for psychosis present with cognitive impairments [1], intermediate between the marked cognitive deficits observed in patients with manifest psychotic disorders, and unaffected healthy controls [2,3,4]. Fractional anisotropy (FA) is the currently most widely applied index of WM organization [8], sensitive to a broad range of neurobiological substrates, such as axonal density, axonal crosssection, myelin and crossing fibers [9]. These WM-alterations have been associated with severity of cognitive deficits [10] and functional outcome [11], and appear to convey a liability for transition to frank psychosis [12]. Individuals at ultra-high risk for psychosis (UHR) present with subtle alterations in cerebral white matter (WM), which appear to be associated with clinical and functional outcome. The effect of cognitive remediation on WM organization in UHR individuals has not been investigated previously
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