Sluggish cognitive tempo
Encyclopedia
Sluggish Cognitive Tempo (SCT) is an unformalized descriptive term which is used to better identify what appears to be a homogeneous sub-subgroup within the formal subgroup "ADHD predominantly inattentive
" (ADHD-I or ADHD-PI). SCT is not recognized in any standard medical manuals such as the DSM-IV or the ICD-10
.
It has been roughly estimated that the SCT population may make up 30-50% of the ADHD-PI population and may even help define a completely new disorder. In many ways, those who have an SCT profile have the opposite symptoms of those with classic ADHD: instead of being hyperactive, extroverted, obtrusive, and risk takers, those with SCT are drifting, introspective and daydreamy, and feel as if "in the fog" (although in excited states, an SCT patient behaves very similarly to a traditional ADHD patient). They also don't have the same risk factors and outcomes. A key behavioral characteristic of those with SCT symptoms is that they are more likely to appear to be lacking motivation. They lack energy to deal with mundane tasks and will consequently seek things that are mentally stimulating because of their underaroused state
, an intense craving for emotional and intellectual stimulation. Those with SCT symptoms show a qualitatively different kind of attention deficit that is more typical of a true information input-output problem, such as memory retrieval and active working memory
, and display a wavering "up and down" mental pattern with extremely variable levels of intense thought, hyperactivity, failing memory, and sexual appetite. Conversely, those with the other two subtypes of ADHD are characteristically excessively energetic and have no difficulty processing information.
It is thought that SCT, ADHD-PI, and ADHD are due to variations in the availability of dopamine
and norepinephrine
, and/or the efficiency of the large chemical structures of the specific receptors and re-uptake receptors. This would explain the efficacy of stimulants such as amphetamines on the treatment of ADHD and SCT.
(Ritalin) at medium-to-high doses, however, a sizable percentage of children with ADHD-PI do not gain much benefit from Ritalin, and when they do benefit, it is at a much lower dose. Tests in lab rats have demonstrated that low doses of Ritalin can increase norepinephrine levels.
Those with ADHD-PI often respond well to amphetamines, such as the prescription medication Adderall
. While methylphenidate and amphetamines have many similar effects on patients (both inhibit reuptake of the neurotransmitters dopamine and norepinephrine, for example), amphetamines also promote release of those neurotransmitters. This positive effect appears to support the hypothesis that SCT is related to neurotransmitter deficiencies.
Selective attention difficulties of those with SCT manifests itself academically, in that they are prone to making more mistakes while working. Those with classic ADHD do not have this difficulty. Those with SCT have difficulty with verbal retrieval from long term memory, but may have greater visual spatial capabilities. They have deficits in working memory which has been described as the ability to keep multiple things in mind for manipulation, while simultaneously 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. They also have a more disorganized thought process, a greater degree of sloppiness, and lose things more easily. They tend to have a greater degree of comorbid learning disabilities. Instead of having greater difficulty selecting and filtering sensory input, as is in the case of SCT, people with other types of ADHD have problems with inhibition.
Studies indicate that comorbid psychiatric problems are more often of the internalizing variety with SCT, such as anxiety
, depression
, and social withdrawal. Their typically shy nature and slow response time has often been misinterpreted as aloofness or disinterest by others. In social group interactions, those with SCT may be ignored. Those with the other types of ADHD are more likely to be rejected in social situations, because of more intrusive or aggressive behavior. Those with classic ADHD also show externalizing problems such as substance abuse
, oppositional-defiant disorder, and, to a lesser degree, conduct disorder
.
Sluggish Cognitive Tempo symptoms were removed from the Inattention symptom list in 1988 because of poor negative predictive power for the inattentive subgroup, and because DSM contributors and editors wanted the inattentive symptoms to be identical for all ADHD subgroups. The presence of the SCT symptoms tended to predict inattention, but the absence of these symptoms did not predict the absence of inattention. This analysis did not take into account the possibility that the SCT symptoms could help predict a distinct grouping within the ADHD/PI subgroup and that the ADHD/PI subgrouping could be heterogeneous in nature.
In the DSM-IV, with its new classification of symptoms for predominately inattentive ADHD, 50 to 70% of those with an ADHD-PI diagnosis have subclinical levels of hyperactivity-impulsiveness symptoms. People with ADHD combined type (ADHD-C) and predominantly hyperactive–impulsive type (ADHD-PHI) may outgrow some, or most of their hyperactive symptoms during or after childhood, while inattentive symptoms typically remain into adulthood. In contrast, those with SCT have had only inattentive features from a young age with little to no history of hyperactivity-impulsiveness. Dr. Russell Barkley has proposed that the DSM-IV designation of ADHD-PI be used only for those displaying purely inattentive symptoms and that those who have had a history of any hyperactivity be designated as ADHD combined subtype. Currently, one can have a few hyperactive symptoms and still receive a diagnosis ADHD-PI.
Currently the American Psychiatric Association
(APA) is working on creating the DSM-5
. In the published preliminary draft revisions, APA writes that more research is needed to assess the "sluggish cognitive tempo" construct.
coordinates actions and strategies for everyday tasks. Dysexecutive syndrome
is defined as a "cluster of impairments generally associated with damage to the frontal lobes of the brain" which includes "difficulties with high-level tasks such as planning, organising, initiating, monitoring and adapting behaviour."
Adele Diamond
has recently postulated that the core cognitive deficit of those with ADHD-PI (ADD), is working memory
, or, as she coined in her recent paper on the subject, "childhood-onset dysexecutive syndrome". She states:
ADHD predominantly inattentive
ADHD predominantly inattentive is one of the three subtypes of Attention-deficit hyperactivity disorder . While ADHD-PI is sometimes still called "attention deficit disorder" by the general public, these older terms were formally changed in 1994 in the new Diagnostic and Statistical Manual of...
" (ADHD-I or ADHD-PI). SCT is not recognized in any standard medical manuals such as the DSM-IV or the ICD-10
ICD-10
The International Statistical Classification of Diseases and Related Health Problems, 10th Revision is a medical classification list for the coding of diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or diseases, as maintained by the...
.
It has been roughly estimated that the SCT population may make up 30-50% of the ADHD-PI population and may even help define a completely new disorder. In many ways, those who have an SCT profile have the opposite symptoms of those with classic ADHD: instead of being hyperactive, extroverted, obtrusive, and risk takers, those with SCT are drifting, introspective and daydreamy, and feel as if "in the fog" (although in excited states, an SCT patient behaves very similarly to a traditional ADHD patient). They also don't have the same risk factors and outcomes. A key behavioral characteristic of those with SCT symptoms is that they are more likely to appear to be lacking motivation. They lack energy to deal with mundane tasks and will consequently seek things that are mentally stimulating because of their underaroused state
Arousal
Arousal is a physiological and psychological state of being awake or reactive to stimuli. It involves the activation of the reticular activating system in the brain stem, the autonomic nervous system and the endocrine system, leading to increased heart rate and blood pressure and a condition of...
, an intense craving for emotional and intellectual stimulation. Those with SCT symptoms show a qualitatively different kind of attention deficit that is more typical of a true information input-output problem, such as memory retrieval and active working memory
Working memory
Working memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
, and display a wavering "up and down" mental pattern with extremely variable levels of intense thought, hyperactivity, failing memory, and sexual appetite. Conversely, those with the other two subtypes of ADHD are characteristically excessively energetic and have no difficulty processing information.
Causes
Like ADHD, those with SCT symptoms have a condition that appears to be genetic in nature. Far less is known about this group yet the impairments seem to indicate the prefrontal cortex region of the brain and difficulties with working memory. The 7-repeat allele polymorphism of the DRD4 gene is also linked more strongly to this group than to ADHD/C and ADHD/PHI subgroups.It is thought that SCT, ADHD-PI, and ADHD are due to variations in the availability of dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
and norepinephrine
Norepinephrine
Norepinephrine is the US name for noradrenaline , a catecholamine with multiple roles including as a hormone and a neurotransmitter...
, and/or the efficiency of the large chemical structures of the specific receptors and re-uptake receptors. This would explain the efficacy of stimulants such as amphetamines on the treatment of ADHD and SCT.
Treatment
Up to 90% of children with ADHD respond well to methylphenidateMethylphenidate
Methylphenidate is a psychostimulant drug approved for treatment of attention-deficit hyperactivity disorder, postural orthostatic tachycardia syndrome and narcolepsy. It may also be prescribed for off-label use in treatment-resistant cases of lethargy, depression, neural insult and obesity...
(Ritalin) at medium-to-high doses, however, a sizable percentage of children with ADHD-PI do not gain much benefit from Ritalin, and when they do benefit, it is at a much lower dose. Tests in lab rats have demonstrated that low doses of Ritalin can increase norepinephrine levels.
Those with ADHD-PI often respond well to amphetamines, such as the prescription medication Adderall
Adderall
Adderall is a brand name of amphetamine salts–based medication used for attention-deficit hyperactivity disorder and narcolepsy. It is a brand-name psychostimulant medication composed of racemic amphetamine aspartate monohydrate, racemic amphetamine sulfate, dextroamphetamine saccharide, and...
. While methylphenidate and amphetamines have many similar effects on patients (both inhibit reuptake of the neurotransmitters dopamine and norepinephrine, for example), amphetamines also promote release of those neurotransmitters. This positive effect appears to support the hypothesis that SCT is related to neurotransmitter deficiencies.
Prognosis
ADHD is a developmental disorder, meaning that certain traits will be delayed in the ADHD individual. These traits can and usually will develop in people with ADHD, but just at a much slower rate than the average person. With ADHD, it has been estimated that this lag could be as high as thirty to forty percent in the development of certain skill sets, such as selective attention. Symptoms of ADHD are often seen by the time a child enters preschool. Those with SCT symptoms typically show a later onset of symptoms in comparison to ADHD. They have greater difficulty with academic tasks and far fewer social difficulties when compared to those with the combined and predominantly hyperactive/impulsive ADHD subtypes.Selective attention difficulties of those with SCT manifests itself academically, in that they are prone to making more mistakes while working. Those with classic ADHD do not have this difficulty. Those with SCT have difficulty with verbal retrieval from long term memory, but may have greater visual spatial capabilities. They have deficits in working memory which has been described as the ability to keep multiple things in mind for manipulation, while simultaneously 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. They also have a more disorganized thought process, a greater degree of sloppiness, and lose things more easily. They tend to have a greater degree of comorbid learning disabilities. Instead of having greater difficulty selecting and filtering sensory input, as is in the case of SCT, people with other types of ADHD have problems with inhibition.
Studies indicate that comorbid psychiatric problems are more often of the internalizing variety with SCT, such as anxiety
Anxiety
Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
, depression
Depression (mood)
Depression is a state of low mood and aversion to activity that can affect a person's thoughts, behaviour, feelings and physical well-being. Depressed people may feel sad, anxious, empty, hopeless, helpless, worthless, guilty, irritable, or restless...
, and social withdrawal. Their typically shy nature and slow response time has often been misinterpreted as aloofness or disinterest by others. In social group interactions, those with SCT may be ignored. Those with the other types of ADHD are more likely to be rejected in social situations, because of more intrusive or aggressive behavior. Those with classic ADHD also show externalizing problems such as substance abuse
Substance abuse
A substance-related disorder is an umbrella term used to describe several different conditions associated with several different substances .A substance related disorder is a condition in which an individual uses or abuses a...
, oppositional-defiant disorder, and, to a lesser degree, conduct disorder
Conduct disorder
Conduct disorder is psychological disorder diagnosed in childhood that presents itself through a repetitive and persistent pattern of behavior in which the basic rights of others or major age-appropriate norms are violated...
.
Prevention
There is no known way to prevent ADHD/PI. Some studies indicate an association between mothers who smoke during pregnancy and a higher rate of ADHD in their children. Avoiding smoking, alcohol, and drugs during pregnancy may help reduce the risk of developing ADHD or similar behavior in offspring.History of the term SCT and its relationship to the DSM
Sluggishness, drowsiness, and daydreaming were the characteristics listed in the DSM-III (in use from 1980–1987) that were to also be present in the diagnosis of Attention Deficit Disorder (ADD) without Hyperactivity. In a study looking at these symptoms, the authors stated that "these symptoms were statistically extracted as a distinct factor". They coined the concept Sluggish Cognitive Tempo. The Sluggish Tempo factor was found to correlate significantly to the Inattention factor, but only when Hyperactivity-Impulsivity symptoms were absent.Sluggish Cognitive Tempo symptoms were removed from the Inattention symptom list in 1988 because of poor negative predictive power for the inattentive subgroup, and because DSM contributors and editors wanted the inattentive symptoms to be identical for all ADHD subgroups. The presence of the SCT symptoms tended to predict inattention, but the absence of these symptoms did not predict the absence of inattention. This analysis did not take into account the possibility that the SCT symptoms could help predict a distinct grouping within the ADHD/PI subgroup and that the ADHD/PI subgrouping could be heterogeneous in nature.
In the DSM-IV, with its new classification of symptoms for predominately inattentive ADHD, 50 to 70% of those with an ADHD-PI diagnosis have subclinical levels of hyperactivity-impulsiveness symptoms. People with ADHD combined type (ADHD-C) and predominantly hyperactive–impulsive type (ADHD-PHI) may outgrow some, or most of their hyperactive symptoms during or after childhood, while inattentive symptoms typically remain into adulthood. In contrast, those with SCT have had only inattentive features from a young age with little to no history of hyperactivity-impulsiveness. Dr. Russell Barkley has proposed that the DSM-IV designation of ADHD-PI be used only for those displaying purely inattentive symptoms and that those who have had a history of any hyperactivity be designated as ADHD combined subtype. Currently, one can have a few hyperactive symptoms and still receive a diagnosis ADHD-PI.
Currently the American Psychiatric Association
American Psychiatric Association
The American Psychiatric Association is the main professional organization of psychiatrists and trainee psychiatrists in the United States, and the most influential worldwide. Its some 38,000 members are mainly American but some are international...
(APA) is working on creating the DSM-5
DSM-5
The next edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders , commonly called DSM-5 , is currently in consultation, planning and preparation...
. In the published preliminary draft revisions, APA writes that more research is needed to assess the "sluggish cognitive tempo" construct.
Relationship to dysexecutive syndrome
The executive system of the human brainBrain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
coordinates actions and strategies for everyday tasks. Dysexecutive syndrome
Dysexecutive syndrome
Dysexecutive syndrome consists of a group of symptoms, usually resulting from brain damage, that fall into cognitive, behavioural and emotional categories and tend to occur together. The term was introduced by Alan Baddeley to describe a common pattern of dysfunction in executive functions, such...
is defined as a "cluster of impairments generally associated with damage to the frontal lobes of the brain" which includes "difficulties with high-level tasks such as planning, organising, initiating, monitoring and adapting behaviour."
Adele Diamond
Adele Diamond
Adele Diamond is one of the founders of the field of Developmental Cognitive Neuroscience. She holds the Canada Research Chair Tier 1 Professorship in Developmental Cognitive Neuroscience at the University of British Columbia , Vancouver...
has recently postulated that the core cognitive deficit of those with ADHD-PI (ADD), is working memory
Working memory
Working memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
, or, as she coined in her recent paper on the subject, "childhood-onset dysexecutive syndrome". She states:
- "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..."
See also
- Depersonalization disorderDepersonalization disorderDepersonalization disorder is a dissociative disorder in which the sufferer is affected by persistent or recurrent feelings of depersonalization and/or derealization. Diagnostic criteria include persistent or recurrent experiences of feeling detached from one's mental processes or body...
- Attention-deficit hyperactivity disorderAttention-deficit hyperactivity disorderAttention deficit hyperactivity disorder is a developmental disorder. It is primarily characterized by "the co-existence of attentional problems and hyperactivity, with each behavior occurring infrequently alone" and symptoms starting before seven years of age.ADHD is the most commonly studied and...
- ADHD predominantly inattentiveADHD predominantly inattentiveADHD predominantly inattentive is one of the three subtypes of Attention-deficit hyperactivity disorder . While ADHD-PI is sometimes still called "attention deficit disorder" by the general public, these older terms were formally changed in 1994 in the new Diagnostic and Statistical Manual of...
- Dysthymia
- HypothyroidismHypothyroidismHypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by other causes such as several conditions of the thyroid gland or, less commonly, the pituitary gland or...
- Bipolar II disorderBipolar II disorderBipolar II disorder is a bipolar spectrum disorder characterized by at least one hypomanic episode and at least one major depressive episode; with this disorder, depressive episodes can be more frequent and are more intense than hypomanic episodes...
- Kleine-Levin SyndromeKleine-Levin syndromeKleine-Levin Syndrome or KLS is aneurological disorder characterized by recurring periods of excessive amounts of sleeping and eating. At the onset of an episode the patient becomes drowsy and sleeps for most of the day and night , waking only to eat or go to the bathroom...