From the May/June 1994 issue
LEARNING DISABILITIES (LD) AND Attention Deficit Hyperactivity Disorder (ADHD) are distinct disorders that not only undermine academic learning, but can interfere with many aspects of life. Both ID and ADHD can result from genetic predisposition or various environmental factors, including perinatal damage, fetal alcohol syndrome, drug use during pregnancy and, in the infant or young adult, lead poisoning, head injury or malnutrition.
Specific disorders of learning are the primary symptoms of a learning disability, but in ADHD they are secondary to the primary symptoms of inattention, impulsiveness and hyperactivity. A learning disability is a disorder in one or more of the basic psychological processes involved in understanding or using written or spoken language that is not due to a sensory or motor handicap, mental retardation, emotional disturbance or environmental disadvantage.
Evidence for the underlying neurological etiology of at least some forms of LD is derived from autopsies of dyslexic brains, as well as from MRIs and PET scans, taken during the performance of specific tasks, which locate and measure brain activity. Nonetheless, because learning problems can also result from emotional disturbances like depression and anxiety, accurate differential diagnosis is crucial Further complicating the diagnosis is the fact that many individuals have both LD and ADHD, and both are associated with secondary emotional difficulties.
Psychiatrist Larry B. Silver, a well-known authority on ID and ADHD, has described four broad categories of learning disabilities: Input, Integration, Memory and Output Disabilities. Input Disabilities include weaknesses in perceiving, or processing, visual or auditory information. People with visual perceptual disabilities can have difficulty organizing the position and shape of what they see (thus confusing letters such as d, b, q, and g), or difficulty distinguishing figure and ground. Auditory perception disabilities include trouble discriminating between different sounds thus confusing words like “hand” and “ham” and difficulty processing, or taking in, sounds as quickly as nnonaffected people.
Second in Silver’s category are Integration Disabilities, which include sequencing disabilities getting wrong the correct order of letters, so that “pot” is read as ‘top,” for example, or being unable to remember the correct order of a series of auditory instructions. Abstraction disabilities interfere with the ability to draw generalizations or to infer meaning from a body of written or spoken material Organizational disabilities are reflected in the problems some people have putting disparate dements into a coherent, integrated whole writing an essay or arranging the contents of a file. People with a short-term auditory or visual Memory Disability have a hard time remembering information they hear but don’t see, or alternately, remembering information they see but don’t hear. Someone with a visual memory disability may understand what he or she reads, but may have difficulty remembering it unless they hear it as well Output Disabilities include problems producing language, as well as fine and gross motor difficulties. Fine motor disabilities include difficulties in writing, while gross motor coordination difficulties show up in physical activities. Silver describes two types of language output difficulties: one in spontaneous language production-trouble initiating conversation and the other in demand language difficulty in responding to requests for specific types of information. Many individuals do not have trouble with spontaneous language, but have trouble with demand language.
Most cognitive tasks require many different abilities. Taking a spelling test, for example, requires visual perception, sequencing and memory, auditory processing and memory, fine motor abilities and visual motor integrative abilities. Neuro-psychological testing can accurately pinpoint the specific area or areas of difficulty, while educational remediation can help individuals to develop compensatory strategies. Thus, someone with poor visual but good auditory memory can be taught to mediate verbally what he or she sees “talk to themselves” in a sense in order to receive the information through their auditory channels.
ADHD is a disorder characterized primarily by inattention, impulsiveness and hyperactivity, while the disorder without hyperactivity is currently referred to as Attention Deficit Disorder (ADD). Adults with ADHD usually exhibit a long history of the following symptoms in varying combination: impulsivity, perseveration, disorganization, explosiveness, occupational dysfunction, as well as chaotic interpersonal relationships and dangerous stimulus-seeking behaviors. Subtler forms of ADHD, predominantly seen in female patients, include disorganization and a chronic tendency to daydream (which impedes occupational success), as well as social awkwardness, inhibition and restlessness that may mask an inability to focus on or stay in relationships. On PET scans of people with ADHD, brain activity appears abnormally diffuse during the performance of focused tasks, while blood-flow studies show decreased blood supply and decreased metabolism in areas of the brain responsible for selective attention, inhibition of emotional overresponsiveness, and overactive behavior.
Scientists hypothesize that the underlying cause of ADHD/ADD is a biochemical inability of the central nervous system to produce enough dopamine and norepinephrine, neurotransmitters required for intellectually demanding situations like studying. Psychostimulant medications normalize neutophysiological functioning either by increasing the concentration of dopamine and norepinephrine at the junction between neurons or stimulating the ability of the receptor neuron to receive these.
Silver suggests that 20 to 25 percent of children and adolescents with ID also have some form of ADHD, while children with ADHD have a 50 to 80 percent probability of having a learning disability. Learning disabilities do not go away, although the development of compensatory strategies can minimize their interference in functioning. It is estimated that between 30 to 70 percent of children with ADHD will continue to have at least some symptoms into adulthood.
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