Attention deficit inattentive disorder
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Understanding Attention Deficit Inattentive Disorder (ADHD-I)
Introduction to ADHD and Inattentiveness
Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by symptoms of inattention, hyperactivity, and impulsivity. Among these, inattentiveness plays a significant role in the lives of individuals with ADHD, impacting their functioning, productivity, and quality of life 1. Despite its importance, inattentiveness has been less frequently studied compared to impulsivity and hyperactivity 1.
Genetic and Environmental Influences on Inattentiveness
Research indicates that inattentiveness in ADHD has a strong genetic component. A meta-analysis of twin and adoption studies found that genetic factors account for approximately 71% of the variance in inattentiveness 2. This suggests that inattentiveness is highly heritable, with dominant genetic effects being more significant for inattentiveness than for hyperactivity 2. Environmental influences, while present, play a smaller role in the manifestation of inattentive symptoms 2.
Neurobiological Distinctions in ADHD-I
The predominantly inattentive subtype of ADHD (ADHD-I) is considered to be neurobiologically distinct from the combined subtype (ADHD-C). While ADHD-C is often associated with disturbances in the striatum (a frontal-striatal loop), ADHD-I is proposed to involve primary disturbances in the cortex (a frontal-parietal loop) 4. This distinction suggests that ADHD-I and ADHD-C may be fundamentally different disorders with unique cognitive and behavioral profiles, comorbidities, and responses to treatment 4.
Prevalence and Demographic Characteristics
Meta-analytic reviews have shown that the predominantly inattentive subtype is the most common form of ADHD in the general population 5. However, individuals with the combined subtype are more likely to be referred for clinical services 5. This discrepancy highlights the need for increased awareness and better diagnostic practices for ADHD-I.
Cognitive and Behavioral Profiles
Children with ADHD-I exhibit different patterns of cognitive and attentional functioning compared to those with ADHD-C. They may show unique attentional styles and are often characterized by sluggish cognitive tempo, which includes symptoms such as daydreaming, mental fogginess, and lethargy 3. These differences have important implications for treatment planning and highlight the necessity for tailored interventions 3.
Validity of ADHD Subtypes
The DSM-IV criteria for ADHD identify three subtypes: predominantly hyperactive-impulsive (ADHD-H), predominantly inattentive (ADHD-I), and combined (ADHD-C). While these subtypes provide a useful clinical framework, their long-term stability and distinctiveness are debated. Research suggests that the differences among subtypes are primarily due to varying levels of inattention and hyperactivity-impulsivity rather than distinct etiological or functional profiles 7. This has led to calls for a dimensional approach to ADHD diagnosis, focusing on the severity of symptoms rather than discrete subtypes 7.
Conclusion
Inattentiveness in ADHD is a critical area of study that requires more focused research. Genetic and neurobiological findings underscore the distinct nature of ADHD-I, while prevalence data and cognitive profiles highlight the need for specialized diagnostic and treatment approaches. Future research should continue to explore the unique characteristics of inattentiveness in ADHD to improve outcomes for affected individuals.
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Most relevant research papers on this topic
Inattentiveness in attention-deficit/hyperactivity disorder
Inattentiveness plays a crucial role in ADHD, impacting patients' functioning and quality of life, but has been studied less frequently than impulsivity and executive function.
Literature Review
Rigorous JournalGenetic and environmental influences on ADHD symptom dimensions of inattention and hyperactivity: a meta-analysis.
Both inattention and hyperactivity are highly heritable, but the type of genetic influence differs between the two symptom dimensions, with dominant genetic effects for inattention and additive genetic effects for hyperactivity.
Meta-Analysis
Highly CitedAttention-deficit/hyperactivity disorder, predominantly inattentive subtype.
ADHD/IA children show different demographic characteristics and comorbid symptomatology than ADHD/C children, and may have a different attentional style.
Literature ReviewHighly CitedAttention-deficit disorder (attention-deficit/ hyperactivity disorder without hyperactivity): A neurobiologically and behaviorally distinct disorder from attention-deficit/hyperactivity disorder (with hyperactivity)
The core problem in the truly inattentive type of ADHD is in working memory, with motivation being more of a problem than inhibitory control, and the primary disturbance in the cortex.
Highly CitedThe Prevalence of DSM-IV Attention-Deficit/Hyperactivity Disorder: A Meta-Analytic Review
The prevalence of DSM-IV ADHD is similar across different diagnostic methods and countries, supporting its diagnostic validity and arguing against the idea that ADHD is a cultural construct limited to the United States or other specific cultures.
Meta-AnalysisHighly CitedJoint analysis of the DRD5 marker concludes association with attention-deficit/hyperactivity disorder confined to the predominantly inattentive and combined subtypes.
The DRD5 marker is associated with attention-deficit/hyperactivity disorder, particularly in the predominantly inattentive and combined subtypes.
Observational StudyHighly CitedValidity of DSM-IV attention deficit/hyperactivity disorder symptom dimensions and subtypes.
The DSM-IV ADHD subtypes provide a convenient clinical shorthand for describing current levels of inattention and hyperactivity-impulsivity symptoms, but lack sufficient long-term stability to justify classification of distinct forms of the disorder.
Meta-AnalysisHighly CitedImaging Functional and Structural Brain Connectomics in Attention-Deficit/Hyperactivity Disorder
Children with ADHD exhibit abnormal brain network dysfunction, correlated with behavior disturbances, which may inform the development of imaging-based biomarkers for diagnosis and treatment evaluation.
Literature ReviewRigorous JournalHighly CitedA systematic review and analysis of long-term outcomes in attention deficit hyperactivity disorder: effects of treatment and non-treatment
Current ADHD treatments may reduce the negative impact of untreated ADHD on life functioning, but do not usually 'normalize' recipients.
Systematic ReviewRigorous JournalHighly CitedMoving towards causality in attention-deficit hyperactivity disorder: overview of neural and genetic mechanisms.
ADHD is linked to abnormal neural circuitry and genetic variants, but the causal relationship between these factors and symptom presentation remains unresolved.
Literature ReviewRigorous JournalHighly Cited