TY - JOUR
T1 - Effects of aripiprazole and haloperidol on neural activation during the n-back in healthy individuals
T2 - A functional MRI study
AU - Goozee, Rhianna
AU - Reinders, Antje A T S
AU - Handley, Rowena
AU - Marques, Tiago
AU - Taylor, Heather
AU - O'Daly, Owen
AU - McQueen, Grant
AU - Hubbard, Kathryn
AU - Mondelli, Valeria
AU - Pariante, Carmine
AU - Dazzan, Paola
PY - 2015
Y1 - 2015
N2 - OBJECTIVE: Antipsychotic drugs target neurotransmitter systems that play key roles in working memory. Therefore, they may be expected to modulate this cognitive function via their actions at receptors for these neurotransmitters. However, the precise effects of antipsychotic drugs on working memory function remain unclear. Most studies have been carried out in clinical populations, making it difficult to disentangle pharmacological effects from pathology-related brain activation. In this study, we aim to investigate the effects of two antipsychotic compounds on brain activation during working memory in healthy individuals. This would allow elucidation of the effects of current antipsychotic treatments on brain function, independently of either previous antipsychotic use or disease-related pathology.METHODS: We carried out a fully counterbalanced, randomised within-subject, double-blinded and placebo-controlled, cross-over study of the effects of two antipsychotic drugs on working memory function in 17 healthy individuals, using the n-back task. Participants completed the functional MRI task on three separate occasions (in randomised order): following placebo, haloperidol, and aripiprazole. For each condition, working memory ability was investigated, and maps of neural activation were entered into a random effects general linear regression model to investigate main working memory function and linear load. Voxel-wise and region of interest analyses were conducted to attain regions of altered brain activation for each intervention.RESULTS: Aripiprazole did not lead to any changes in neural activation compared with placebo. However, reaction time to a correct response was significantly increased following aripiprazole compared to both placebo (p=0.046) and haloperidol (p=0.02). In contrast, compared to placebo, haloperidol dampened activation in parietal (BA 7/40; left: FWE-corr. p=0.005; FWE-corr. right: p=0.007) and frontal (including prefrontal; BA 9/44/46; left: FWE-corr. p=0.009; right: FWE-corr. p=0.014) cortices and the left putamen (FWE-corr. p=0.004). Compared with aripiprazole, haloperidol dampened activation in parietal cortex (BA7/40; left: FWE-corr. p=0.034; right: FWE-corr. p=0.045) and the left putamen (FWE-corr.p=0.015). Haloperidol had no effect on working memory performance compared with placebo.CONCLUSION: Cognitive functions are known to be impaired in schizophrenia and as such are an important target of treatments. Elucidating the mechanisms by which antipsychotic medications alter brain activation underlying cognition is essential to advance pharmacological treatment of this disorder. Studies in healthy individuals can help elucidate some of these mechanisms, whilst limiting the confounding effect of the underlying disease-related pathology. Our study provides evidence for immediate and differential effects of single-dose haloperidol and aripiprazole on brain activation during working memory in healthy individuals. We propose that these differences likely reflect their different receptor affinity profiles, although the precise mechanisms underlying these differences remain unclear.
AB - OBJECTIVE: Antipsychotic drugs target neurotransmitter systems that play key roles in working memory. Therefore, they may be expected to modulate this cognitive function via their actions at receptors for these neurotransmitters. However, the precise effects of antipsychotic drugs on working memory function remain unclear. Most studies have been carried out in clinical populations, making it difficult to disentangle pharmacological effects from pathology-related brain activation. In this study, we aim to investigate the effects of two antipsychotic compounds on brain activation during working memory in healthy individuals. This would allow elucidation of the effects of current antipsychotic treatments on brain function, independently of either previous antipsychotic use or disease-related pathology.METHODS: We carried out a fully counterbalanced, randomised within-subject, double-blinded and placebo-controlled, cross-over study of the effects of two antipsychotic drugs on working memory function in 17 healthy individuals, using the n-back task. Participants completed the functional MRI task on three separate occasions (in randomised order): following placebo, haloperidol, and aripiprazole. For each condition, working memory ability was investigated, and maps of neural activation were entered into a random effects general linear regression model to investigate main working memory function and linear load. Voxel-wise and region of interest analyses were conducted to attain regions of altered brain activation for each intervention.RESULTS: Aripiprazole did not lead to any changes in neural activation compared with placebo. However, reaction time to a correct response was significantly increased following aripiprazole compared to both placebo (p=0.046) and haloperidol (p=0.02). In contrast, compared to placebo, haloperidol dampened activation in parietal (BA 7/40; left: FWE-corr. p=0.005; FWE-corr. right: p=0.007) and frontal (including prefrontal; BA 9/44/46; left: FWE-corr. p=0.009; right: FWE-corr. p=0.014) cortices and the left putamen (FWE-corr. p=0.004). Compared with aripiprazole, haloperidol dampened activation in parietal cortex (BA7/40; left: FWE-corr. p=0.034; right: FWE-corr. p=0.045) and the left putamen (FWE-corr.p=0.015). Haloperidol had no effect on working memory performance compared with placebo.CONCLUSION: Cognitive functions are known to be impaired in schizophrenia and as such are an important target of treatments. Elucidating the mechanisms by which antipsychotic medications alter brain activation underlying cognition is essential to advance pharmacological treatment of this disorder. Studies in healthy individuals can help elucidate some of these mechanisms, whilst limiting the confounding effect of the underlying disease-related pathology. Our study provides evidence for immediate and differential effects of single-dose haloperidol and aripiprazole on brain activation during working memory in healthy individuals. We propose that these differences likely reflect their different receptor affinity profiles, although the precise mechanisms underlying these differences remain unclear.
U2 - 10.1016/j.schres.2015.02.023
DO - 10.1016/j.schres.2015.02.023
M3 - Article
C2 - 25778615
SN - 0920-9964
JO - Schizophrenia Research
JF - Schizophrenia Research
ER -