Highlights Disturbed glycemic control is an intrinsic feature of schizophrenia. The neurotransmitter dopamine has a key role in regulating glucose homeostasis. We studied brain dopamine and blood glucose levels in first episode psychosis. The relationship between glucose and brain dopamine is altered in schizophrenia.

There are pronounced behavioural and neuroimaging parallels between cocaine abuse and narcissism. Although the observed commonalities are not specific to cocaine as opposed to other types of addiction, we argue that the relatively constrained molecular actions of cocaine and, more importantly, the covariance of narcissism-like behaviours with cocaine use build a strong case for taking the known effects of cocaine as a starting point for addressing the hitherto underinvestigated neurophysiology of narcissism. In this review, we discuss the potential relevance of cocaine abuse as a pharmacological model of narcissism. We outline previous research on the role of monoamines across several domains affected in narcissistic personality disorder and subclinical narcissism, namely, selected personality traits, social behaviour, emotional empathy and self-referential processing. We propose that dysregulation in dopamine signalling might underlie addiction-like features of narcissism and that altered serotonergic signalling may account for affective components of narcissism and, in particular, explain the differences between grandiose and vulnerable subtypes. In conclusion, we provide recommendations for future research.

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