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A systematic review and meta-analysis of the cyclic alternating pattern across the lifespan


Cyclic alternating pattern (CAP) is the electroencephalogram (EEG) pattern described as a marker of sleep instability and assessed by NREM transient episodes in sleep EEG. It has been associated with brain maturation. Aging is associated with homeostatic process disruptions, including changes in the electroencephalogram (EEG) during sleep. Cyclic alternating pattern (CAP) is seen as a marker of unstable sleep. The analysis of CAP, therefore, has been considered a sensitive tool for the investigation of pathologic brain processes and brain maturation signaling .


The aim of this review was to evaluate the normative data of CAP parameters according to the aging process in healthy subjects through a systematic review and meta-analysis.


Two authors independently searched databases using PRISMA guidelines. Discrepancies were reconciled by a third reviewer. Subgroup analysis and tests for heterogeneity were conducted. For inclusion, studies had to fulfill the following criteria and the exclusion criteria: Studies in unhealthy participants, case reports or case series with fewer than 10 cases.


Of 286 studies, 10 submitted a total of 168 healthy individuals to CAP analysis. Scoring of CAP can begin at 3 months of life, when K-complexes, delta bursts, or spindles can be recognized. Rate of CAP increased with age, mainly during the first 2 years of life, then decreased in adolescence, and increased in the elderly. The A1 CAP subtype and CAP rate were high in school-aged children during slow-wave sleep (SWS). A1 CAP subtypes were significantly more numerous in adolescents compared with other groups, while the elderly showed the highest amounts of A2 and A3 CAP subtypes. Our meta-analysis registered the lowest CAP rate in infants younger than 2 years old and the highest in the elderly.


This review summarized the normative data of CAP in NREM sleep during the aging process. The CAP rate increased with age and sleep depth, especially during SWS. Parameters of CAP may reflect gender hormonal effects and neuroplasticity. More reports on CAP subtypes are needed for their reference values establishment. This analysis provides normative data on the healthy sleep microstructure, but equally suggests that more studies are warranted to elucidate whether sex hormones influence age related changes of sleep instability in peripubertal and postmenopausal individuals.


Cyclic Alternating Pattern, Systematic Review, Meta-analysis, Lifespan


Área Clínica


UNIRIO - Rio de Janeiro - Brasil


Debora Petrungaro Migueis, Maria Cecilia Lopes, Priscila Dias Ignacio, Luiz Claudio Thuler, Maria Helena Araujo-Melo, Karen Spruyt, Glenda Lacerda