ADHD and Autism Overview

ADHD: Over-Diagnosis and Under-Diagnosis

• ADHD is a common neurodevelopmental disorder characterized by:
  • Persistent inattention
  • Hyperactivity
  • Impulsivity
• The consistency of ADHD diagnosis is questioned, with concerns about over-diagnosis in some populations and under-diagnosis in others.

ADHD Over-Diagnosis

• Empirical evidence suggests over-diagnosis due to contextual or methodological errors.
• Relative Age Effect: Younger children in school cohorts are more likely to be diagnosed due to developmental immaturity.
  • Zoega et al. (2012) found that in Iceland, children born just before the school-entry cutoff were more likely to be prescribed ADHD medication.
  • Elder (2010) documented similar patterns in the US and Canada.
  • Highlights a lack of developmental sensitivity in clinical examinations.
• Subjective and Biased Reporting: ADHD diagnosis relies on conduct, with strong reliance on subjective parent and teacher reports.
  • Merten et al. (2017) hypothesized that teachers might over-report disruptive behaviors, especially in boys, mistaking normal hyperactivity for psychopathology.
• Gender Prejudice:
  • Boys are three times more likely to be diagnosed with ADHD than girls (Bruchmuller et al., 2012).
  • Girls often have inattentive symptoms, which are less likely to be flagged.
  • Bruchmuller's study found doctors were more likely to diagnose ADHD when the hypothetical child was male, despite a similar symptom profile.
• Medicalization of Conduct: Concerns that behavioral checklists medicalize conduct, failing to account for normative developmental variability (Mandy, 2017).
• Biopsychosocial Model:
  • Timimi & Taylor (2004) argue that Western societies' growing intolerance of childhood behavioral variance has resulted in the pathologization of natural developmental differences.
  • Singh (2008) contests this view, suggesting high diagnostic rates may reflect better access to mental health treatments and more knowledge.
• Over-diagnosis may occur in settings that prioritize discipline and academic performance, leading to quick diagnoses and pharmaceutical treatments.
• Teacher-reported checklists are susceptible to bias due to classroom demands and gendered expectations.

ADHD Under-Diagnosis

• Ethnic Disparities:
  • Black and Latino children in the US are less likely to be diagnosed or treated for ADHD than white children, despite similar symptom severity.
  • Cultural stigma, clinician bias, and inadequate access to healthcare are factors.
  • Eiradi et al. (2006) found minority parents were less likely to report ADHD symptoms or seek treatment due to concerns about labeling and distrust of healthcare experts.
  • UK studies show Black Caribbean children are less likely to be diagnosed with ADHD but more likely to be reprimanded at school (House of Commons Education Committee, 2021).
• Socioeconomic Status:
  • Lower-income families may have less access to mental health examinations and face service delays (Russell et al., 2016).
  • Inadequate housing can worsen ADHD-like behaviors, confounding the diagnosis process.
• Girls are frequently underdiagnosed because they present with inattentive symptoms, which are less disruptive.
• Cultural norms may discourage mental health care or lead to interpreting symptoms using non-clinical frameworks.

Gene-Environment Interaction

• Twin studies indicate ADHD is highly heritable (around 70%) (Faraone, 2019).
• Environmental risk factors like prenatal exposure to smoking play a significant role.
• Symptoms change with age, environment, and other factors.
• Leitner (2014) discusses how autism can disguise ADHD symptoms, leading to missed diagnosis.

Medical Treatment and Diagnostic Approaches

• Early ADHD work used cross-sectional designs and parent-teacher rating instruments, which are prone to informant bias and do not account for developmental change.
• Neuroimaging research (Shaw et al., 2017) has found evidence of neurodevelopmental abnormalities in ADHD, including delayed cortical maturation.
• NICE guidelines (2018) urge multimodal assessment involving teachers, parents, and clinicians, considering co-occurring disorders and developmental stages.
• Children in underdiagnosed groups are less likely to get behavioral therapies or medication, leading to poor long-term outcomes (Danielson et al., 2018).

Conclusion

• Understanding ADHD through developmental psychopathology emphasizes the role of genetic vulnerabilities, environmental impacts, and clinician training.
• Dynamic relationships exist between individual predispositions and contextual effects like parental style, peer interactions, and school environment.
• ADHD symptoms are influenced by a child’s larger ecology.

Additional Information (Lecture Notes)

• ADHD symptoms interfere with social or school functioning.
• Prevalence:
  • Poland: 0.8%
  • Northern Ireland: 6.0%
  • Global: Around 5% (Saya et al., 2018)
• Some children hide symptoms due to stigma.
• Gender Differences:
  • Boys are three times more likely to be diagnosed than girls (Willcutt, 2012).
  • Boys are more likely to be referred for clinical treatment (Sayal, 2006).
• Working memory is a better predictor of academic achievement than classroom behavior (Rapport et al., 2000).

Autism: Diagnostic Criteria and Clinical Heterogeneity

• Autism is a neurodevelopmental disorder characterized by:
  • Difficulties in social communication.
  • Repetitive patterns of interest or activities.
• Diagnosis relies on behavioral criteria rather than biological markers.
• Autism is clinically heterogeneous, with a wide range of symptoms, severity levels, and cognitive profiles.

DSM Diagnostic Criteria

• Two core domains:
  • Social Communication and Social Interaction:
    • Deficits in social-emotional reciprocity.
    • Deficits in nonverbal communicative behaviors.
    • Difficulties in developing and understanding relationships.
  • Restricted and Repetitive Behaviors:
    • Stereotyped motor movements.
    • Insistence on sameness and rigid adherence to routines.
    • Highly restricted and fixated interests.
    • Hyper- or hypo-reactivity to sensory input.
• Symptoms must appear in the early developmental period and cause clinically significant impairment.
• DSM-5 conceptualizes autism as a single spectrum condition with varying levels of severity and support needs (Lord et al., 2020).

Evidence for Clinical Heterogeneity

• Symptom Variability:
  • Ranges from nonverbal with extensive assistance needs to near-typical language abilities and independent living.
  • Lord et al. (2018) found symptom severity ranged from severe social communication deficits to mild social awkwardness.
  • Variances exist even within the same diagnostic domain (e.g., severe repetitive motor behaviors vs. fixation on sameness).
• Developmental Trajectories:
  • Some children make significant advances in language and adaptive functioning, while others remain seriously disabled (Gotham et al., 2012).
• Cognitive Characteristics:
  • 30-50% have intellectual disability (Baio et al., 2018), while others have average or above-average intelligence.
  • Some have splinter skills or specific talents.
• Cognitive Theories:
  • Theory of mind deficiencies: Difficulty understanding others' perspectives.
  • Executive dysfunction theories.
  • Weak central coherence theories.

Genetic and Environmental Factors

• Twin studies indicate high heritability (more than 80%).
• Hundreds of genetic variations have been linked, each accounting for a small number of cases (Sandin et al., 2017).
• De novo mutations in genes like CHD8 and SHANK3 have been identified.
• Genetic risk interacts with environmental factors:
  • Advanced parental age
  • Prenatal infection exposure
  • Perinatal difficulties
• Two individuals may receive the same diagnosis but have different genetic etiologies and environmental factors (Swanson, 2003).

Changes in Symptoms Over Time

• Symptoms may become more or less severe as people mature.
• Comorbid mental health problems (anxiety, ADHD, intellectual disability) add complexity (Lai et al., 2019).
• Social withdrawal due to anxiety might be misinterpreted as primary autism.
• Executive functioning difficulties from ADHD resemble repetitive behaviors in autism.
• Longitudinal studies demonstrate that profiles can shift significantly from early childhood into adolescence.

Conclusion

• Symptom severity, cognitive functioning, genetics, environmental exposures, and developmental trajectories contribute to the wide range of autism-related characteristics.
• Understanding this variation is essential for accurate diagnosis and tailored therapies.
• Future research must acknowledge the richness and distinctiveness of autism.
• Improved diagnostic techniques are needed to capture a wider range of symptom presentations across genders, races, and developmental stages.
• Early detection and targeted intervention measures can significantly impact developmental outcomes.

Additional Information (Lecture Notes)

• Leo Kanner (1943) observed 11 children with similar patterns of behavior: difficulty with language development, social skills deficit, insistence on sameness.
• DSM still uses the term Autism Spectrum Disorder (ASD).
• 20% of anxiety disorders co-occur with autism across multiple countries.
• Diagnosis relies on behavioral observation and screening; there is no blood test, scan, or brain imaging.
• Differences have been found between autistic and non-autistic individuals in the amygdala.