title: Scaling behavior of human locomotor activity amplitude: association with bipolar disorder.
abstract: Scale invariance is a feature of complex biological systems, and abnormality of multi-scale behaviour may serve as an indicator of pathology. The hypothalamic suprachiasmatic nucleus (SCN) is a major node in central neural networks responsible for regulating multi-scale behaviour in measures of human locomotor activity. SCN also is implicated in the pathophysiology of bipolar disorder (BD) or manic-depressive illness, a severe, episodic disorder of mood, cognition and behaviour. Here, we investigated scaling behaviour in actigraphically recorded human motility data for potential indicators of BD, particularly its manic phase. A proposed index of scaling behaviour (Vulnerability Index [VI]) derived from such data distinguished between: [i] healthy subjects at high versus low risk of mood disorders; [ii] currently clinically stable BD patients versus matched controls; and [iii] among clinical states in BD patients.
authors.affiliation: Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America. Premananda.Indic@umassmed.edu
authors.forename: Premananda
authors.initials: P
authors.lastname: Indic
authors.forename: Paola
authors.initials: P
authors.lastname: Salvatore
authors.forename: Carlo
authors.initials: C
authors.lastname: Maggini
authors.forename: Stefano
authors.initials: S
authors.lastname: Ghidini
authors.forename: Gabriella
authors.initials: G
authors.lastname: Ferraro
authors.forename: Ross J
authors.initials: RJ
authors.lastname: Baldessarini
authors.forename: Greg
authors.initials: G
authors.lastname: Murray
mesh_terms: D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D055815:Young Adult