neurodevelopmental disorders Flashcards
neurodevelopmental disorders
The neurodevelopmental disorders involve developmental deficits that impair personal, social, academic, and/or occupational functioning and usually begin early in development (before the child starts school).
Intellectual Disability
For this diagnosis, the person must have (a) deficits in intellectual functioning as determined by the results of a clinical assessment and a score that is about two standard deviations below the mean on an individualized, standardized intelligence test; (b) deficits in adaptive functioning that cause a failure to meet community standards of personal independence and social responsibility and impair functioning in one or more activities of daily life in multiple contexts; and (c) an onset of the deficits during the developmental period. A specifier is used to indicate level of severity (mild, moderate, severe, or profound), which is based on adaptive functioning in conceptual, social, and practical domains and is useful for determining the amount of support the person needs. The cause of intellectual disability is known in 25 to 50% of all cases. Of cases with a known etiology, about 80 to 85% are due to prenatal factors (which includes chromosomal and other genetic causes), 5 to 10% are due to perinatal factors (e.g., asphyxia), and 5 to 10% are due to postnatal factors. The most common chromosomal causes are Down’s syndrome followed by fragile X syndrome, and the most common preventable prenatal cause is fetal alcohol syndrome (Kilgus, Maxmen, & Ward, 2015).
Autism Spectrum Disorder (ASD):
The diagnosis of ASD requires the presence of (a) deficits in social communication and social interaction and (b) restrictive and repetitive patterns of behaviors, interests, and activities. Deficits in social communication and interaction include impairments in social-emotional reciprocity, nonverbal communication, and developing and maintaining relationships. Restrictive and repetitive behaviors, interests, and activities include stereotyped or repetitive motor movements, use of objects, or speech; inflexible adherence to routines; and preoccupation with unusual objects. For the diagnosis, the onset of symptoms must be during the early developmental period. A specifier is used to indicate symptom severity, which is determined by the level of support required. The prognosis for ASD is best when the person has an IQ over 70, functional language skills by age five, and an absence of comorbid mental health problems.
Associated features of ASD include intellectual and language impairments, self-injurious behaviors (e.g., head banging), motor abnormalities (e.g., clumsiness, walking on tiptoes), and disruptive/challenging behaviors. In addition, individuals with ASD often have impaired face recognition and emotion recognition, which have been identified as contributors to deficits in social relationships. In a study on face recognition, Dawson et al. (2002) compared the reactions of children 3- to 4-years of age with and without autism to novel and familiar faces and objects. While children without autism reacted differently to novel versus familiar faces and objects, children with autism reacted differently to novel and familiar objects but similarly to novel and familiar faces. With regard to emotion recognition, Fridenson-Hayo et al. (2016) found that children with autism had deficits in recognizing basic and complex emotions in all three expression modalities (face, voice, and body).
Reported prevalence rates for ASD in the United States and other countries vary, but most range from 1 to 2% of the population. It is diagnosed three to four times more often in males than in females. The etiology of ASD is unknown, but it is believed to be due to multiple genetic and non-genetic factors. Family, twin, and adoption studies provide support for the genetic inheritance of this disorder. For example, reported concordance rates for monozygotic twins range from 69 to 95%, while rates for dizygotic twins range from 0 to 24% (Ray, 2021). Non-genetic risk factors include male gender, birth before 26 weeks of gestation, advanced parental age, and exposure to certain environmental toxins during prenatal development (Gialloreti et al., 2019). Despite extensive research, a link between ASD and childhood vaccinations has not been established (e.g., Hviid et al., 2019).
ASD has been linked to several brain and neurotransmitter abnormalities: Studies have found accelerated brain growth in children with ASD that begins at about 6 months of age and plateaus by the preschool years and that corresponds to a larger-than-normal head circumference and increased brain volume and weight during that period. Abnormalities have also been found in the cerebellum, corpus callosum, and amygdala (Davlantis & Dawson, 2017). With regard to neurotransmitters, individuals with ASD often have lower-than-normal levels of serotonin in several areas of the brain but elevated levels of serotonin in the blood. One explanation for this difference is that blood serotonin enters the fetal brain during the early stages of development before the blood-brain barrier is fully mature, which causes reduced development of or damage to serotonergic neurons in the brain (Whitaker-Azmitia, 2005). Other neurotransmitters that contribute to ASD include dopamine, GABA, glutamate, and acetylcholine.
The primary goals for the treatment of children with ASD are to minimize the core symptoms of the disorder, maximize independence by promoting the acquisition of functional skills, and reduce or eliminate behaviors that may interfere with functional skills (Hyman & Levy, 2020). With regard to nonpharmacological interventions, early intensive behavioral intervention (EIBI) is an evidence-based treatment that uses the principles and techniques of applied behavior analysis (ABA). An example is Lovaas’s (1987) method of EIBI, which involved providing young children with ASD with at least 40 hours per week of behavioral interventions and included using shaping and discrimination training to teach nonspeaking children to communicate verbally. Research evaluating the outcomes of EIBI have found that it has the greatest positive impact on intelligence and language acquisition and a smaller and less consistent impact on adaptive skills, social functioning, and severity of core ASD symptoms (Weitlauf et al., 2014).
No medication has been found to be effective for the core symptoms of ASD, and medications are ordinarily prescribed for co-occurring psychiatric conditions and associated behaviors that cause distress but are not addressed by or haven’t been alleviated by nonpharmacological interventions. For instance, methylphenidate and other psychostimulants are used to alleviate symptoms of ADHD; SSRIs are used to treat depression and anxiety; and atypical antipsychotics (especially risperidone and aripiprazole) are used to reduce irritability and aggressive, self-injurious, and other disruptive behaviors.
Attention-Deficit/Hyperactivity Disorder (ADHD):
ADHD involves a pattern of inattention and/or hyperactivity-impulsivity that has persisted for at least six months, had an onset before 12 years of age, is present in at least two settings, and interferes with social, academic, or occupational functioning. The diagnosis requires at least six symptoms of inattention and/or at least six symptoms of hyperactivity-impulsivity (or at least five symptoms for individuals age 17 and older). Symptoms of inattention include doesn’t listen when spoken to, fails to pay close attention to details, doesn’t follow through on instructions, is easily distracted by extraneous stimuli, and is often forgetful in daily activities. Symptoms of hyperactivity-impulsivity include is unable to engage in play or leisure activities quietly, often runs or climbs in inappropriate situations, talks excessively, has trouble waiting his/her turn, and interrupts or intrudes on others. A specifier is used to indicate the subtype as predominantly inattentive presentation, predominantly hyperactive/impulsive presentation, or combined presentation.
ADHD is twice as common in males than females during childhood but the gender difference decreases somewhat in adulthood when the ratio of males to females is about 1.6:1. Up 80% of school-age children with ADHD continue to meet the diagnostic criteria for the disorder in adolescence, and up to 30% continue to do so into adulthood (Hinshaw et al., 2006; Mannuzza et al., 1993; Weiss & Hechtman, 1993). However, symptoms tend to vary over the lifespan, with overactivity decreasing the most during adolescence and adulthood, inattention decreasing slightly during adolescence and adulthood, and impulsivity decreasing slightly and changing in adulthood to include such behaviors as driving recklessly and abruptly quitting a job or ending a relationship (Biederman, 2011; Weiss, Hechtman, & Weiss, 1999).
Children with ADHD have high rates of comorbidity. Although the reported rates of specific comorbid disorders vary somewhat, most studies have found oppositional defiant disorder to be the most common comorbid disorder followed by, in order, conduct disorder, an anxiety disorder, and a depressive disorder (e.g., Bauermeister, et al., 2007; Cuffe, et al., 2015).
ADHD has been linked to a number of brain abnormalities. Structural neuroimaging studies have found that overall brain volume and the volumes of the caudate nucleus, putamen, nucleus accumbens, amygdala, and hippocampus are smaller in people with ADHD (Radboud University Nijmegen Medical Centre, 2017). In addition, children and adolescents with this disorder have delayed cortical maturation (especially in the prefrontal cortex), while adults have reduced cortical thickness. Functional neuroimaging studies have identified hyper- or hypoactivation in several brain networks. For example, these studies have found that children with ADHD often exhibit hypoactivation in the frontoparietal network, which consists of the dorsolateral and anterior prefrontal cortex, anterior cingulate cortex, lateral cerebellum, caudate nucleus, and inferior parietal lobe (Cortese, et al., 2012). ADHD has also been linked to abnormalities in dopamine, norepinephrine, and serotonin activity (Austin, n.d.).
A genetic contribution has been confirmed by the results of family, twin, and adoption studies which indicate that ADHD is one of the most heritable of all psychiatric disorders (Schachar, 2014). For example, twin studies suggest a genetic contribution in about 76% of cases (Faraone et al., 2005). In addition, there’s evidence that ADHD shares the same inherited genetic variations with major depressive disorder, bipolar disorder, schizophrenia, and autism spectrum disorder (Cross-Disorder Group of the Psychiatric Genomics Consortium, 2013). ADHD has also been linked to low birth weight, premature birth, and maternal smoking or alcohol use during pregnancy. Finally, Barkley (1997) describes the proximal cause of ADHD to be a deficit in behavioral inhibition which affects four executive neurocognitive functions that depend on behavioral inhibition – working memory; internalization of speech; self-regulation of affect, motivation, and arousal; and reconstitution (behavioral analysis and synthesis). In turn, these functions influence the motor system that controls goal-directed behavior.
The best treatment for ADHD depends, to some degree, on the person’s age. For example, guidelines prepared by the American Academy of Pediatrics (Wolraich et al., 2019) recommend the following for children and adolescents: (a) Parent- and teacher-administered behavioral interventions are the treatment-of-choice for preschool children, with evidence-based parent training in behavioral management (PTBM) being the primary recommended intervention. Included in this category are the positive parenting program and parent-child interaction therapy (PCIT). Medication is prescribed only when behavioral interventions do not produce adequate improvement. (b) For elementary and middle-school children, the recommended treatment is a combination of medication and behavioral interventions at home and at school. (c) For adolescents, the recommendation is to prescribe medication with the adolescent’s assent and to combine medication with behavioral and instructional interventions when they are available. There is evidence that adolescents may benefit, for example, from behavioral therapy, motivational interviewing, mindfulness-based training, and classroom training (e.g., Buitelaar, 2017; Evans, Owens, Wymbs, & Ray, 2018). For adults, the first-line treatment is medication, but several psychosocial interventions have also been found to have beneficial effects, with cognitive behavior therapy having the strongest support (Fullen, Jones, Emerson, & Adamou, 2020). Note that, while ADHD in childhood has been linked to an increased risk for substance use problems in adolescence and adulthood, the research suggests this link is not due to treatment with a psychostimulant in childhood: A meta-analysis of the research conducted by Humphreys, Eng, and Lee (2013) found that children with ADHD who do and do not receive a psychostimulant drug are comparable in terms of rates of future substance-related problems. Based on their results, these investigators conclude that treatment of ADHD during childhood with a psychostimulant neither decreases nor increases the risk for later substance use disorders.
Tic Disorders
The DSM-5 defines a tic as a “sudden, rapid, recurrent, nonrhythmic motor movement or vocalization” (p. 81). Motor tics include eye blinking, facial grimacing, shoulder shrugging, and echopraxia, while vocal tics include throat clearing, barking, and echolalia. The DSM-5 distinguishes between three tic disorders: The diagnosis of Tourette’s disorder requires at least one vocal tic and multiple motor tics that may occur together or at different times, may wax and wane in frequency but have persisted for more than one year, and had an onset before 18 years of age. The diagnosis of persistent (chronic) motor or vocal tic disorder requires one or more motor or vocal tics that have persisted for more than one year and began before age 18. The diagnosis of provisional tic disorder requires one or more motor and/or vocal tics that have been present for less than one year and began before age 18. The onset of tics is typically between four and six years of age, and the severity of tics ordinarily peaks between 10 and 12 years of age (American Psychiatric Association, 2013). The tic disorders often co-occur with other psychiatric disorders, with ADHD being the most common comorbid disorder for Tourette’s disorder (Cravedi et al., 2017).
Tourette’s disorder has been linked to dopamine overactivity, a smaller-than-normal caudate nucleus, and heredity. Treatment may include an antipsychotic drug (e.g., haloperidol) and medication for comorbid conditions – e.g., serotonin for obsessive-compulsive symptoms and methylphenidate or clonidine for ADHD. Behavioral treatments include comprehensive behavioral intervention for tics (CBIT), which consists of psychoeducation, social support, and habit reversal, competing response, and relaxation training.
Communication Disorders
These disorders involve deficits in language, speech, and communication. Included in this category is childhood-onset fluency disorder (stuttering), which involves a disturbance in normal fluency and time patterning of speech that’s inappropriate for the person’s age and language skills, persists over time, and includes one or more of seven symptoms: sound and syllable repetitions, sound prolongations, broken words, audible or silent blocking, circumlocutions, words pronounced with excessive physical tension, monosyllabic whole-word repetitions. The onset is usually between two and seven years of age. Sixty-five to 85% of children recover from dysfluency, with the severity of symptoms at age eight being a good predictor of persistence or recovery. The treatment-of-choice is habit reversal training which incorporates several strategies including competing response training that, for this disorder, is regulated breathing.
Specific Learning Disorder
The diagnosis of this disorder requires difficulties related to academic skills as indicated by the presence of at least one of six symptoms that last for at least six months despite the use of interventions that address difficulties: inaccurate or slow and effortful word reading; difficulty understanding the meaning of what is read; difficulties with spelling; difficulties with written expression; difficulties mastering number sense, number facts, or calculation; and difficulties with mathematical reasoning. For the diagnosis, the person’s academic skills must be substantially below those expected for his/her age, interfere with academic or occupational performance or activities of daily living, have an onset during the school-age years, and not be better accounted for by another disorder or condition (e.g., uncorrected visual or auditory impairment). Specifiers are used to indicate subtype (with impairment in reading, with impairment in written expression, or with impairment in mathematics) and level of severity. About 5 to 15 percent of school-age children have a specific learning disability and approximately 80% of these children have a reading disorder (American Psychiatric Association, 2018). Of the reading disorders, dyslexia is the most common type; of the types of dyslexia, dysphonic dyslexia is most common. It involves difficulties connecting sounds to letters and is also known as dysphonetic, auditory, and phonological dyslexia (Healy, 2010; Keller & Goldberg, 2005). People with a specific learning disorder usually have an average to above-average IQ but elevated rates of other problems and disorders, with studies finding ADHD to be the most common comorbid psychiatric disorder (Khodeir, El-Sady, & Mohammed, 2020).
