Cognitive deficits are a common, but not consistent, feature of schizophrenia. Indeed, whilst most patients exhibit some general cognitive impairment compared to antecedent expectations, up to a quarter display cognitive performance in the normal range.
The heterogeneous cognitive profile associated with schizophrenia poses potential problems for pro-cognitive drug trials. Including cognitively normal patients within a sample may inflate baseline scores, thus reducing the scope to see improvement between treatment and placebo groups.
In order to examine this potential issue, this research, presented at ISCTM / SIRS / CINP 2018, investigated participant-level trajectories of cognitive performance among patients with schizophrenia.
A post-hoc analysis was conducted using existing trial data from 463 patients with schizophrenia who participated in a randomized, double-blind, placebo-controlled, Phase II, pro-cognitive drug trial.
Participants completed the Cambridge Neuropsychological Test Automated Battery (CANTAB) and the MATRICS Consensus Cognitive Battery (MCCB) at four separate time points (screening, baseline, week six and week 12).
Participants performing within a clinically-normal range at screening (on the MCCB composite) were also performing within the top 35% on domain-specific subtests of CANTAB and MCCB for visual learning and memory, working memory and sustained attention / vigilance.
Poorer performers on CANTAB Paired Associates Learning task (PAL) (>10 errors) at screening demonstrated an improvement in performance across baseline, week six and week 12 time points. In contrast, the top 25% of good performers on PAL at screening (<10 errors) demonstrated stable performance indicative of little, or no change, across the remainder of the study visits.
Interested in learning more about participant-level trajectories of cognitive performance in patients with schizophrenia? Download this poster.