Sluggish Cognitive Tempo is Not New

Before there was Predominantly Inattentive ADHD (ADHD-PI) there was Sluggish Cognitive Tempo (SCT). SCT was first described in the DSM III (The American Pyschiatric Association Manual for Diagnosis, 3rd edition) that was published in the 1980s. The symptoms of SCT, physical hypoactivity, mental fogginess, daydreaming, confusion, and lack of mental alertness were considered to be the hallmark symptoms of what psychiatrist then called Attention Deficit Disorder (ADD) without hyperactivity or ADD-WO.

Studies of ADHD in the late seventies had found a subgroup of kids with ADD with a pattern of inattention that was different from the inattention seen in the majority of people with ADHD. The Inattentive subgroup of ADHD with Hyperactivity had inattention problems that were characterized by sloppy work and distractability while the inattentive subgroup without hyperactivity had inattention problems that were related to symptoms of cognitive and physical underarousal.

It was researchers in the late seventies that called this cluster of symptoms by the unfortunate title of 'Sluggish Cognitive Tempo' and this was the title given to these symptoms in the DSM III. These symptoms however were removed from the DSM in 1988 when the DSM IV was published because, while these under arousal type symptoms predicted that the person would be inattentive, the lack of these symptoms did not predict that the person would not be inattentive. In scientific terms these symptoms had a poor negative predictive power and because of this, they were removed from the DSM IV completely.

The problem with removing this group completely was that about 30% to 50% of people with the Inattentive type of ADHD had SCT symptoms and the more researchers looked at this group, it became apparent that the problems that this group had were different from the problems that the ADHD group had.   The more you looked at these symptoms the more you realized that treatment would need to be different and psychiatrist have decided to revisit this cluster of symptoms and to try to determine if they deserve there own home in the new DSM V to be published in 2013.

Researchers have now started the hard work on figuring out the science of SCT.  The biology of SCT is unknown. Most of what we know about neurotransmitter action would point to norepinephrine as the culprit for the under arousal seen in SCT but no studies, that I know of, have found biological markers for a norepinephrine problem in people with symptoms of SCT. The drug Atomoxetine (Stattera) uniquely targets nor-epinephrine re-uptake but no study, that I have found, has indicated that Strattera is the answer for people with SCT symptoms.

Research studies aim to understand how the inattention of ADHD-PI differs from the inattention of SCT. One study found that the inattention of ADHD-PI was related to exeuctive function deficits and working memory problems while the inattention of SCT involved more of a problem with sustained attention.  The information that we know is just now trickling in.  Let us hope, for the sake of all the millions of folks out there suffering with these symptoms, that the pace of this information flow will soon quicken.

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Child Neuropsychol. 2010;16(4):350-65. Epub 2010 Jun 23.
DSM-IV-defined inattention and sluggish cognitive tempo: independent and interactive relations to neuropsychological factors and comorbidity.

Wåhlstedt C, Bohlin G.

Department of Psychology, Uppsala University, Uppsala, Sweden.


The aim of the present study was to investigate the independent relations of DSM-IV-defined inattention and behaviors characteristic of sluggish cognitive tempo (SCT) to neuropsychological factors and problem behaviors often comorbid with attention deficit/hyperactivity disorder (ADHD). By controlling for symptoms of DSM-IV-defined inattention, unique relations to SCT could be ascertained. Additionally, interactive relations of DSM-IV-defined inattention and SCT were of interest. A community-based sample of school children (N = 209; the higher end of the ADHD-symptom range was oversampled) completed neuropsychological tasks designed to measure executive function (EF), sustained attention, and state regulation. Behavioral symptoms were measured using parental and teacher ratings of the DSM-IV criteria for ADHD and Oppositional Defiant Disorder (ODD). The results showed that these two domains of inattention, DSM-IV-defined inattention and SCT, have neuropsychological processes and comorbid behavioral problems in common. However, when controlling for the overlap, DSM-IV-defined inattention was uniquely related to EF and state regulation, while SCT was uniquely related to sustained attention. In addition, the results showed an interactive relation of DSM-IV-defined inattention and SCT to ODD. Findings from the present study support the notion that DSM-IV-defined inattention constitutes a somewhat heterogeneous condition. Such results can further our theoretical understanding of the neuropsychological impairments and comorbid behavioral problems associated with ADHD symptoms.

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