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Theories of ADHD - Coggle Diagram
Theories of ADHD
What is ADHD
SUBTYPES OF ADHD
INATTENTION
: fail to pay attention, difficulty sustaining attention, does not seem to listen, fails to follow through on instructions, difficulty organising tasks, easily distracted, often forgetful or loses things
HYPERACTIVE-IMPULSIVE
: restless, fidgety, squirmy, often "on the go", talks excessively, difficulty awaiting turn, interrupts or intrudes, blurts out answers
DIAGNOSTIC CRITERIA
early onset of symptoms (prior to age 12)
symptoms occur in two or more settings
clear evidence of significant impairment
heterogeneity
Polanczyk et al 2014
: prevalence rates virtually unchanged across studies 1985-2012 when adhering to the strict diagnostic criteria
SEX DIFFERENCES WITHIN ADHD
Gaub and Carlson 1997
: boys have ADHD more than girls across community and referral samples
Martin et al 2018
: genetic risk manifests in differing symptom presentation in females versus males
Methods of diagnosis
Clinical interviews and questionnaires
Conners (parent, teacher, and self report scale)
SDQ (strengths and difficulties questionnaire)
SWAN (strengths and weaknesses of ADHD and normal behaviour)
Attention tasks
Conners Continuous Performance Task
Go/No-Go Task
Challenges to Diagnosis
No gold standard criteria/test/cognitive marker
criteria can be highly subjective
diagnostic methods and criteria do not include non-specific problems than are highly common in ADHD
high level of overlapping diagnostic behaviours with other conditions
ADHD, anxiety, mania, depression, and ODD all share some level of symptom overlap
lack of irritability as a diagnostic hallmark is only criteria separating ADHD from other conditions
behaviours reflecting the same diagnostic category can change with time
Galera et al 2011
: only 7-20% of children with ADHD at 6yo show persistent features across early development
CHALLENGES ASSOCIATED WITH ADHD
academic problems linked to inattention (
Breslau et al 2007
)
clinical and non-clinical social deficits (
Kofler et al 2011
)
discrimination (
Stickley et al 2019
)
higher risk of substance abuse linked to hyperactivity (
Elkins et al 2007
)
increased risk of mood, anxiety, and addictive disorders
NEUROCOGNITIVE THEORIES
EXECUTIVE FUNCTION
Suggests that ADHD is a deficit in normal executive functioning
SUPPORT
Willcutt et al 2005
: Group differences between ADHD and HC found across all executive functioning tasks
Nigg et al 2005
: fewer than half of children wit ADHD show a significant impairment on any one EF task
Sadozai et al 2024
: meta analysis showing group differences between ADHD and HC on different executive functioning tasks with
biggest effects within working memory domains
Skogan et al 2015
: parent-reported difficulties within inhibiton and working memory in pre-school significantly correlated with child ADHD symptoms
AGAINST
Sadozai et al 2024
: executive function difficulties are not specific to ADHD (common and transdiagnostic)
REWARD RESPONSE
suggests that ADHD is associated with delay aversion, poor delayed-gratification, and sub-optimal reward processing
Sonuga-Barke et al 1994
: individuals with ADHD choose immediate small rewards instead of larger delayed rewards
Tripp and Alsop 1999
: children with ADHD find it difficult to modify their behaviour in response to reinforcers
MULTIPLE PATHWAY MODEL
Solanto et al 2001
: considering performances on tasks measuring both inhibition and delay-aversion was better at classifying ADHD vs controls
Sonuga-Barke et al 2003
: both inhibition and delay-aversion predicted unique variance in preschoolers
ATTENTION
INTERFERENCE HYPOTHESIS
: suggests that ADHD is associated with difficulty in sustaining attention due to interference from the default mode network
Default Mode Network
: brain network anti-correlated with task-positive networks ("swicthed on" when we are "switched off")
AROUSAL
suggests that ADHD is a hypo-aroused cortical state, resulting in compensation such as hyperactive motor behaviour
Geissler et al 2014
: many of the observed features of ADHD (e.g. sleep, appetite, reaction time, EEG markers) consistent with the theory
NEUROBIOLOGICAL THEORIES
HERITABILITY
Faraone et al 2005
: meta analysis of twin studies showing 0.76 heritability rate of ADHD
high level of genetic influence on the condition
ENVIRONMENTAL FACTORS
Low birth weight (
Nigg et al 2006
)
neglect or abuse (
Famularo et al 1992
)
maternal alcohol abuse or dependence while in utero (
Knopik et al 2005
)
maternal smoking while in utero (
Kotimaa et al 2003
)
Interaction with genetic risk
pre-natal smoke exposure interacts with DAT1 polymorphism which is associated with ADHD subtypes (
Neuman et al 2007
)
DOPAMINERGIC TRANSMISSION
Typical Development
EXECUTIVE FUNCTION
: a set of domain-general skills used to control and co-ordinate other cognitive abilities and behaviours
Miyake and Friedman 2012
: executive functions show unity and diversity, have a genetic component, are related to clinical phenomena, and have developmental stability
Unity and Diversity framework
: suggests that three key EFs can be decomposed into a common EF, with a focus on how individual specific elements can map onto underlying cognitive processes
Common EF
: the ability to actively maintain task-goals and goal-related information, and the ability to use this information to bias lower-level processing
Shifting specific component
: reflects the flexibility and ease of transitioning to new task-set representations
Executive functions are the key building blocks for complex cognitive tasks such as planning and problem solving
Can be split into
HOT
and
COLD
functions
HOT EXECUTIVE FUNCTIONS
: related to arousal and motivation; linked to the orbitofrontal cortex, ventromedial prefrontal cortex, and anterior cingulate
COLD EXECUTIVE FUNCTIONS
: related to planning and task execution; linked to the rostral prefrontal and dorsolateral prefrontal cortex
Self regulation
: the ability to act and control behaviour in everyday situations