Canine hyperactivity, impulsivity, and inattention share similar demographic risk factors and behavioural comorbidities with human ADHD

Sini Sulkama,Salla Mikkola,Milla Salonen,César Araujo,Emma Hakanen,Jenni Puurunen,Hannes Lohi

doi:10.1038/s41398-021-01626-x

Abstract

Attention-deficit hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder impairing the quality of life of the affected individuals. The domestic dog can spontaneously manifest high hyperactivity/impulsivity and inattention which are components of human ADHD. Therefore, a better understanding of demographic, environmental and behavioural factors influencing canine hyperactivity/impulsivity and inattention could benefit both humans and dogs. We collected comprehensive behavioural survey data from over 11,000 Finnish pet dogs and quantified their level of hyperactivity/impulsivity and inattention. We performed generalised linear model analyses to identify factors associated with these behavioural traits. Our results indicated that high levels of hyperactivity/impulsivity and inattention were more common in dogs that are young, male and spend more time alone at home. Additionally, we showed several breed differences suggesting a substantial genetic basis for these traits. Furthermore, hyperactivity/impulsivity and inattention had strong comorbidities with compulsive behaviour, aggressiveness and fearfulness. Multiple of these associations have also been identified in humans, strengthening the role of the dog as an animal model for ADHD.

Highlights

Attention-deficit hyperactivity disorder (ADHD) is a highly heritable, childhood-onset neurodevelopmental disorder with an estimated worldwide prevalence of 2–7% in humans [1, 2]
ADHD can be classified into three different presentations: predominantly hyperactive/impulsive, predominantly inattentive or combined type [3]
ADHD persists into adulthood with several comorbidities, such as learning impairments, autism spectrum disorder and anxiety disorders [1, 4], making the disorder a detrimental condition if not diagnosed and treated appropriately

Summary

Introduction

Attention-deficit hyperactivity disorder (ADHD) is a highly heritable, childhood-onset neurodevelopmental disorder with an estimated worldwide prevalence of 2–7% in humans [1, 2] It is characterised by the presence of persistent and inappropriate levels of motor overactivity, impulsivity and inattention [1, 3], caused by abnormalities in attention and reward processing, inhibitory control and emotional regulation [4, 5]. Impulsivity, a component of human ADHD [3], is characterised by impaired motor inhibitory control and an inability to tolerate gratification delay [6] It is a dimension of the normal personality continuum observed across species, including humans and dogs [6, 7]. High levels of impulsivity are considered abnormal and are associated with other detrimental behaviours, such as aggression, in several species, including humans [8,9,10], rodents [11, 12] and dogs [13,14,15,16,17]

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