Amotivation is associated with smaller ventral striatum volumes in older patients with schizophrenia

作者：Caravaggio Fernando; Fervaha Gagan; Iwata Yusuke; Plitman Eric; Chung Jun Ku; Nakajima Shinichiro; Mar Wanna; Gerretsen Philip; Kim Julia; Chakravarty M. Mallar; Mulsant Benoit; Pollock Bruce; Mamo David; Remington Gary; Graff-Guerrero Ariel^*

来源：International Journal of Geriatric Psychiatry, 2018, 33(3): 523-530.

DOI：10.1002/gps.4818

• accumbens
• amotivation
• apathy
• dopamine
• D2
• 3 receptor
• morphology
• motivation
• occupancy
• schizophrenia
• ventral striatum

ObjectiveMotivational deficits are prevalent in patients with schizophrenia, persist despite antipsychotic treatment, and predict long-term outcomes. Evidence suggests that patients with greater amotivation have smaller ventral striatum (VS) volumes. We wished to replicate this finding in a sample of older, chronically medicated patients with schizophrenia. Using structural imaging and positron emission tomography, we examined whether amotivation uniquely predicted VS volumes beyond the effects of striatal dopamine D-2/3 receptor (D2/3R) blockade by antipsychotics.
MethodsData from 41 older schizophrenia patients (mean age: 60.26.7; 11 female) were reanalysed from previously published imaging data. We constructed multivariate linear stepwise regression models with VS volumes as the dependent variable and various sociodemographic and clinical variables as the initial predictors: age, gender, total brain volume, and antipsychotic striatal D2/3R occupancy. Amotivation was included as a subsequent step to determine any unique relationships with VS volumes beyond the contribution of the covariates. In a reduced sample (n=36), general cognition was also included as a covariate.
ResultsAmotivation uniquely explained 8% and 6% of the variance in right and left VS volumes, respectively (right: =-.38, t=-2.48, P=.01; left: =-.31, t=-2.17, P=.03). Considering cognition, amotivation levels uniquely explained 9% of the variance in right VS volumes (=-.43, t=-0.26, P=.03).
ConclusionWe replicate and extend the finding of reduced VS volumes with greater amotivation. We demonstrate this relationship uniquely beyond the potential contributions of striatal D2/3R blockade by antipsychotics. Elucidating the structural correlates of amotivation in schizophrenia may help develop treatments for this presently irremediable deficit.

• 出版日期2018-3
• 单位McGill