Attention-Deficit/Hyperactivity Disorder (ADHD), a common neuro-behavioral disorder, affects children at an early age and its symptoms may continue in adults. The disorder impacts the individual's social as well as academic development. The multifactorial nature of ADHD is likely due to the combination of genetic, environmental, and neurological factors. Family history poses a great risk for ADHD development and is known to involve genes that regulate neurotransmitters associated with attention, impulses, and behavior. Maternal smoking during pregnancy, metal ion and toxin exposure and traumatic brain injury are some of the environmental factors that increase the risk of ADHD. Further, brain imaging studies in ADHD have shown altered structure and brain activity specifically in the prefrontal cortex. Reduced prefrontal cortex volume and altered brain connections in ADHD patients result in impulsivity, poor behavioral control, and difficulty in maintaining attention. Although with no cure, ADHD can be successfully managed, and some symptoms may improve as the child ages.
TopIntroduction And Background
A neurodevelopmental condition known as Attention-Deficit/Hyperactivity Disorder (ADHD) is most typically diagnosed in childhood, however its symptoms can last into adulthood. The disorder is marked by recurrent patterns of impulsivity, hyperactivity, and inattentiveness that severely impede day-to-day operations, personal development and may have detrimental effects on a variety of aspects of a person's life including relationships, profession, academic success and overall quality of life (Wilens & Spencer, 2010). Though the actual etiology of ADHD is unknown, research indicates that it is most likely the result of a complex interaction of genetic, environmental, and neurological variables and the proportional importance of each element varies between individuals. Furthermore, studies are being conducted to better understand the complex interplay between these factors (Thapar, Cooper, Eyre, Langley, & Psychiatry, 2013).
Earlier ADHD was believed to impact children with symptoms progressively disappearing throughout adolescence or the early stages of adulthood. However, follow-up studies showed the persistence of ADHD from childhood to adulthood (Sibley, Mitchell, & Becker, 2016) rather the disorder affected a significant population of adults (Song et al., 2021). The prevalence of ADHD in childhood has been reported to be 5%-7% (Polanczyk, De Lima, Horta, Biederman, & Rohde, 2007) and 1/3 of the patients are positive for persistent ADHD (Barbara Franke et al., 2018). A recent review indicated the pooled prevalence of ADHD in adults to be 3.10% where ADHD-I (inattentive type of ADHD) remained the commonest type of ADHD, followed by ADHD-HI (hyperactive type) and ADHD-C (combined type) (Ayano et al., 2023). Further, the prevalence rate of ADHD in adult population is higher than other well-known mental disorders including bipolar disorders (1%) and some anxiety disorders including post-traumatic stress disorder (PTSD), Obsessive-compulsive disorder (OCD), Generalized anxiety disorder (GAD) and panic disorders (Clemente et al., 2015). Several factors such as drug usage, harsh childhood experiences, the severity of the disorder and/or untreated ADHD throughout childhood may be responsible for the persistence of ADHD in adults (Kessler et al., 2005). ADHD treatment necessitates a thorough and customized strategy that takes into account the particular requirements and difficulties of every patient. A successful and satisfying life may be achieved by those with ADHD by combining several treatment approaches and offering continuous support.
This chapter seeks to provide succinct information on the variables that are important in the development of ADHD, assisting us in comprehending the complex elements that lead to this crippling condition (Figure 1).
Figure 1. Schematic representation of the factors contribution to ADHD
TopFactors Contributing To Adhd
ADHD is known to be familial and is a highly heritable disorder (Chen et al., 2017). ADHD has a high heredity rate when compared rates reported in autism spectrum disorder (ASD), bipolar disorder, and schizophrenia (Sullivan, Daly, & O'donovan, 2012). ADHD heritability has been estimated to be 77-88% based on family and twin studies conducted in recent decades (Faraone & Larsson, 2019). Further findings imply that the relative risk of ADHD for first-degree relatives is 5- to 10-fold (B Franke et al., 2012) which applies to core symptoms and is gender-independent (Martin et al., 2018)