[Sluggish cognitive tempo: an updated review].

INTRODUCTION: The study of sluggish cognitive tempo (SCT) arose largely from research carried out on attention deficit hyperactivity disorder (ADHD). This construct is defined by a range of behavioural symptoms such as the appearance of drowsiness, daydreaming, physical hypoactivity, little initiative, lethargy and apathy.

DEVELOPMENT: The construct of SCT is reviewed by means of recently published papers on its clinical characteristics, associated symptoms, evaluation, prevalence, aetiology, comorbidity, neuropsychological profiles and treatment. The latest studies propose that SCT should be understood as a cluster of symptoms that is distinct from ADHD. Although there is no clear consensus on the matter, the evidence is becoming increasingly more consistent and endows SCT with a high degree of external validity, associating it with internalising symptoms.

CONCLUSIONS: We believe the different subtypes of ADHD must be grounded in attentional conceptual models. Hence, the attentional guidance network would be related with SCT, the vigilance or sustained attention network would be linked with the inattentive subtype of ADHD, and executive attention would be involved in the combined subtype of ADHD. The evidence obtained to date, including this review, supports the idea that SCT is an attention disorder distinct from ADHD but, like any dimensional disorder, it can overlap with it in around half the cases.