Qualitatively different attention deficit
Those with SCT show a qualitatively different kind of attention deficit more typical of a true information input and output problem, then from those who have had a significant history of hyperactivity-impulsivity. SCT children show lower selective attention, sustained focus, and memory retrieval problems more typical of a learning disability profile. They are more prone to making mental errors, have difficulty with verbal retrieval from long term memory, and also have greater visual spacial deficits. They have deficits in working memory which has been described as the ability to keep multiple things in mind for manipulation, while keeping this information free from internal distraction. Consequently, mental skills such as calculation, reading, and abstract reasoning are often more challenging for those with SCT. Instead of having greater difficulty selecting and filtering sensory input as is the case in SCT, people with ADHD/C and ADHD/PHI, have problems with inhibition, distractibility, and low goal persistence.
Differences from other types of ADHD
Reaction time and processing speeds are notably slower for those with SCT. In contrast to ADHD-C and ADHD-HI, people with a sluggish cognitive tempo are characteristically hypoactive, self conscious, "spacey", passive, and withdrawn. A key behavioural characteristic of the disorder is that those with SCT are more likely to be lacking motivation. They become easily bored with things that do not stimulate them and thus will seek things of interest because of their underaroused state. Conversely, those with the other two subtypes of ADHD are characteristically more extroverted, impulsive, distracted, and driven. Other behaviours typical of this condition is a more disorganized thought process, sloppiness, more careless mistakes, and a greater tendency to lose things more easily.
Comorbid psychiatric problems
Studies indicate that Comorbid psychiatric problems are more often of the internalizing variety, such as anxiety, depression, and social withdrawal. The typically shy nature and slow response time of those with SCT has often been misinterpreted as aloofness and disinterest. In social group interactions they may be ignored. Those with the other types of ADHD are more likely to show externalizing problems such as substance abuse, oppositional-defiant disorder, and to a lesser degree conduct disorder.
Treatment
It has been suggested that Psychosocial interventions are more successful for those with SCT then for those with "typical" ADHD.
Those with SCT do not respond to methylphenidate (Ritalin) to anywhere near the same degree as do those with ADHD/C and ADHD/PHI. Roughly one in five responds with a theraputic decrease in symptoms, while two thirds of this population will show mild benefits. It has been suggested that amphetamine (Adderall) has a greater success rate because unlike Methlphenidate, it also promotes the release of the neurotransmitters dopamine and norepinephrine. Those with SCT also generally respond better to smaller doses then do the other two subtypes of ADHD.
Could SCT be an instance of childhood-onset dysexecutive syndrome?
Adele Diamond has recently postulated that the core cognitive defitcit of SCT is working memory. She stated:
- "Instructional methods that place heavy demands on working memory will disproportionately disadvantage individuals with ADD".
- "language problems often co-occur with ADD, and it is suggested that part of the reason might be that linguistic tasks, especially verbal ones, tax working memory so heavily. Spatial and artistic skills, however, are often preserved or superior in individuals with ADD."
- "The working memory deficit in many children with ADD is accompanied by markedly slowed reaction times, a characteristic that covaries with poorer working memory in general".
- "Individuals with ADD have difficulty maintaining a sufficiently high level of motivation to complete a task...They go looking for something else to do or think about because they are bored...to remedy a general lower arousal level.."