The relationship between apathy and impulsivity in large population samples

Pierre Petitet,Jacqueline Scholl,Bahaaeddin Attaallah,Sanjay Manohar,Daniel Drew,Masud Husain

doi:10.1038/s41598-021-84364-w

Abstract

Apathy and impulsivity are debilitating conditions associated with many neuropsychiatric conditions, and expressed to variable degrees in healthy people. While some theories suggest that they lie at different ends of a continuum, others suggest their possible co-existence. Surprisingly little is known, however, about their empirical association in the general population. Here, gathering data from six large studies (n = 3755), we investigated the relationship between measures of apathy and impulsivity in young adults. The questionnaires included commonly used self-assessment tools—Apathy Evaluation Scale, Barratt Impulsiveness Scale (BIS-11) and UPPS-P Scale—as well as a more recent addition, the Apathy Motivation Index (AMI). Remarkably, across datasets and assessment tools, global measures of apathy and impulsivity correlated positively. However, analysis of sub-scale scores revealed a more complex relationship. Although most dimensions correlated positively with one another, there were two important exceptions revealed using the AMI scale. Social apathy was mostly negatively correlated with impulsive behaviour, and emotional apathy was orthogonal to all other sub-domains. These results suggest that at a global level, apathy and impulsivity do not exist at distinct ends of a continuum. Instead, paradoxically, they most often co-exist in young adults. Processes underlying social and emotional apathy, however, appear to be different and dissociable from behavioural apathy and impulsivity.

Highlights

To being partly dissociable, these two neuropsychiatric disorders share some common neural substrates? The “dopamine overdose hypothesis” within the Parkinson’s disease (PD), schizophrenia, and addiction literature is compatible with this view
Using data collected in large population samples, we investigated the relationship between the two syndromes and their constituent dimensions
The result is consistent with recent observations in clinical populations such as ADHD5, frontotemporal lobar dementia[14,15], and P D35

Summary

Introduction

To being partly dissociable, these two neuropsychiatric disorders share some common neural substrates? The “dopamine overdose hypothesis” within the Parkinson’s disease (PD), schizophrenia, and addiction literature is compatible with this view. If the two disorders originate from the disruption of parallel circuits that may or may not partially overlap (e.g., “circuit-specific” model), their incidence should be either independent from one another, or positively correlated If, they implicate opposite neuromodulatory dysregulations of the same networks (e.g., “dopamine overdose hypothesis”), apathy and impulsivity should never be found concurrently, and should negatively correlate (within- and acrosssubjects). Apathy and impulsivity have mostly been described as separate, but positively correlated, factors[5,14,15,34], even in PD p atients[35] These observations seemingly provide little support for these constructs being at different ends of a single axis (as formulated by the “dopamine overdose hypothesis”), the following potential confound is worth considering. The fine-grained dissection of the components of apathy and impulsivity, and the characterisation of their relationship with one another, are essential prerequisites to any investigation of their brain bases and therapeutic treatments

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