ADHD: Fall 2024 Lecture Notes PDF

Attention Deficit Hyperactivity Disorder Adapted from Disorders of childhood: Development and Psychopathology, Parritz and Troy 2011 Chapter 9 Neurotypical behaviour Expect a 5-year old to sit through this lecture? Listen to directions before beginning assignment There is ag...

Attention Deficit Hyperactivity Disorder Adapted from Disorders of childhood: Development and Psychopathology, Parritz and Troy 2011 Chapter 9 Neurotypical behaviour Expect a 5-year old to sit through this lecture? Listen to directions before beginning assignment There is age-related improvement in memory and attention Executive functions E.g., attending to directions, raise hand before calling out answer, wait quietly for other students, following rules Introduction to ADHD Attention-Deficit/Hyperactivity Disorder (ADHD) is classified as a developmental disorder by the DSM5. Disorders that initially present in children tend to be labeled as developmental disorders. The essential feature of ADHD is a persistent pattern of inattention and/or hyperactivity-impulsivity. Importantly, these factors must be shown to impact development in a clinically significant manner. Diagnosis of ADHD At the clinical level, ADHD is diagnosed as one of three types: (i)inattentive type, (ii) hyperactive/impulsive type or (iii) combined type Diagnosed based on criteria/symptoms laid out in DSM-5-TR (see next slide) Diagnosis is based on symptoms that have occurred over past 6 months, with an age of onset typically < 12 years (for children) INATTENTIVE TYPE Is often distracted by Does not follow through on extraneous stimuli (for older instructions & doesn't adolescents & adults, may complete schoolwork, chores include unrelated thoughts) or job duties (may start tasks but quickly loses focus) Has problems staying focused Has problems organizing on tasks or activities, such as tasks & work (for instance, during lectures, conversations or does not manage time well; long reading has messy, disorganized work; misses deadlines) Does not seem to listen when Avoids or dislikes tasks spoken to directly (e.g., seems that require sustained elsewhere) mental effort, such as preparing reports & completing forms INATTENTIVE TYPE Often loses things needed for tasks or daily life, such as school papers, books, keys, wallet, cell phone & eyeglasses Doesn't pay close attention to details or makes careless mistakes in school or job tasks (e.g. overlooks or misses details, work is inaccurate) Forgets daily tasks, such as doing chores & running errands. Older teens & adults may forget to return phone calls, pay bills & keep appointments HYPERACTIVE/ IMPULSIVE TYPE Fidgets with or taps hands or Unable to play or do leisure feet, or squirms in seat activities quietly Not able to stay seated (in Always "on the go”, as if classroom, workplace) driven by a motor Runs about or climbs where it Talks too much is inappropriate HYPERACTIVE/ IMPULSIVE TYPE Blurts out an answer before a question has been finished (for instance may finish people's sentences, can't wait to speak in conversations) Interrupts or intrudes on others (for instance, cuts into conversations, games or activities, or starts using other people's things without permission). Older teens & adults may take over what others are doing Has difficulty waiting his, her, or their turn, such as while waiting in line Combined Type *for 17 and older 5 of 9https://www.caddra.ca/wp-content/uploads/CADDRA-ADHD-Practice-Guidelines-4.1-English.pdf Key Features of ADHD A key feature of the ADHD diagnostic is that manifestations of the disorder must appear in multiple settings. This means that ADHD symptoms are not just limited to one place (school, for example), but appear no matter where the child is. Context matters. Signs of the disorder may be minimal or absent when the individual is under close supervision, receiving frequent rewards for good behavior, in a novel setting, or doing something interesting. This can make the disorder challenging to diagnose, as the doctor’s office often meets all of the above criteria. The issues associated with ADHD tend to create other problems in the child’s life. Academic performance tends to suffer. Social rejection is common as well. Other comorbid disorders may also make it more challenging (e.g., ASD, OCD) ADHD is not considered an intellectual disorder per se. Nevertheless, mild delays in language, motor and social development are common in children with ADHD. This could be a consequence of simply not paying sufficient attention to things.  Prevalence of ADHD Prevalence of ADHD is approximately 7.6% - recent 2023 meta-analysis! Male to female ratio is about 3:1 Adult ADHD may have a prevalence as high as 2.5%. Longitudinal studies of ADHD show that symptoms gradually reduce across the lifespan, but persist in 30-50% of cases. Impulsivity and hyperactivity tend to drop off more than attention. Many adults continue to struggle with attention their entire lives. ADHD prevalence appears to vary worldwide, though not by as much as is often claimed. North America, when considered as a Worldwide prevalence estimated by meta-analysis of whole, has higher rates of ADHD than 102 ADHD studies (Polanczyk 2007). most other places (South America and Africa being exceptions). Prevalence of ADHD: Importance of Culture Even with the same official diagnostic criteria, the diagnosis of ADHD is difficult to separate from the cultural context. The current DSM5 diagnostic criteria still seems to be based largely on elementary school-aged North If ADHD prevalence is roughly the American boys. same worldwide, would it be noticed in hunter-gatherer children? If ADHD occurs everywhere in the world, it would still only be diagnosable in certain cultural contexts. Hyperactivity and inattentiveness would not be as much of a concern in times and places where children do not go to school. On the other hand, in areas where academic achievement is prized above all else, even minor levels of inattentiveness and hyperactivity would seem pathological. The rich interaction between cultural factors and ADHD is not unique. Or would it only be seen when As we will see, disorders such as anorexia nervosa are children are subjected to also highly dependent on cultural context. extremely high academic standards from an early age?  Comorbidity of ADHD Only about 1/3 of children are diagnosed with ADHD alone. The majority are diagnosed with at least one other DSM disorder. What causes ADHD? Genetics of ADHD ADHD is elevated in first-degree biological relatives of individuals with ADHD. First-degree biological relatives are relatives that share 50% of their genetic material. Your siblings are your first-degree relatives, as are your parents. The etiology of ADHD has been suggested to be up to 80% genetic. This makes it one of the most heritable disorders. Strong overlap with genes for Autism Spectrum Disorder In spite of the strong evidence for a genetic link, research has not yet uncovered much in the way of specific genes that might be to blame. Weak associations have been found with genes for the dopamine reuptake transporter and the D4 dopamine receptor. Environmental/developmental risk factors There is evidence for gene-environment interactions in ADHD. Children with a specific mutation in the dopamine reuptake transporter (DAT1) are more likely to exhibit symptoms of ADHD if their mothers smoked during pregnancy. Perinatal hypoxia – a temporary shortage of oxygen around the time of birth – has also been linked to the development of ADHD. There is no convincing evidence that ADHD in the general population can be caused by exposure to food coloring or preservatives. Children who are known to be sensitive to these things do show some hyperactivity when they are exposed, but they are not reflective of all ADHD cases. There is also no evidence that ADHD is caused by, or exacerbated by sugar. Behavioural markers of ADHD Children with ADHD are much less likely to be able to ‘wait’ for the second m  “Go, No-Go” Task Untreated individuals with ADHD make more errors of commission and errors  Iowa Gambling Task Untreated individuals with ADHD more likely to pick from ‘risky’ deck  Behavioral markers of ADHD Rewards apparently have less of an influence over the behavior of children with ADHD. These deficits point to issues with either executive function (frontal lobe) or reward function (mesocorticolimbic dopamine system), or perhaps both at the same time. Also show impairments in behaviour The Dual Pathway Model is a requiring inhibitory control. theory about ADHD suggesting dysfunctions in both systems are What areas of the brain are affected? Brain areas implicated in ADHD How exactly are these brain areas affected ? Treatment of ADHD Despite the complexity of the ADHD diagnosis, the efficacy of the available pharmacological treatment options is actually quite good. Drugs are effective in 70-90% of cases. The most common pharmacological treatments for ADHD are drugs of the psychostimulant variety. These have been in regular use since at least the 1970s. Popular drugs include methylphenidate (Ritalin/Concerta), amphetamine (Adderall), and d- amphetamine (Dexedrine). These drugs are given at low doses, in long-acting, slow- release formats that limit the “rush” that characterizes their illegal counterparts. How do they work? ADHD medications target the dopamine system in the brain Ethics of ADHD treatment Because ADHD is mostly a disorder of childhood, its treatment requires special consideration. It is often suggested that children are overmedicated, or that medication is used as a substitute for effective parenting/schooling. Children are not small adults, so studies of drug effects on adult brains cannot be safely generalized to children. Emerging data from animal studies of chronic psychostimulant treatment suggest that long-term side effects may exist. Chronic methylphenidate treatment in young rats reduces the rewarding power of cocaine in adulthood. Chronic amphetamine treatment reduces dopamine terminals in the striatum of monkeys. ADHD symptoms do tend to improve on their own as the child ages. Should we just leave ADHD alone and let it resolve itself? Academic and social success during childhood strongly influences the rest of the individual’s life. The possible risks of medication may be a fair tradeoff for a lifetime’s worth of positive outcomes?