Brain oscillatory complexity across the life span.
OBJECTIVE
Considering the increasing use of complexity estimates in neuropsychiatric populations, a normative study is critical to define the 'normal' behaviour of brain oscillatory complexity across the life span.


METHODS
This study examines changes in resting-state magnetoencephalogram (MEG) complexity - quantified with the Lempel-Ziv complexity (LZC) algorithm - due to age and gender in a large sample of 222 (100 males/122 females) healthy participants with ages ranging from 7 to 84 years.


RESULTS
A significant quadratic (curvilinear) relationship (p<0.05) between age and complexity was found, with LZC maxima being reached by the sixth decade of life. Once that peak was crossed, complexity values slowly decreased until late senescence. Females exhibited higher LZC values than males, with significant differences in the anterior, central and posterior regions (p<0.05).


CONCLUSIONS
These results suggest that the evolution of brain oscillatory complexity across the life span might be considered a new illustration of a 'normal' physiological rhythm.


CONCLUSIONS
Previous and forthcoming clinical studies using complexity estimates might be interpreted from a more complete and dynamical perspective. Pathologies not only cause an 'abnormal' increase or decrease of complexity values but they actually 'break' the 'normal' pattern of oscillatory complexity evolution as a function of age.
Departamento de Psiquiatría y Psicología Médica, Universidad Complutense de Madrid, Madrid, Spain. aferlucas@med.ucm.es
Alberto
A
Fernández
Pilar
P
Zuluaga
Daniel
D
Abásolo
Carlos
C
Gómez
Anahi
A
Serra
María Andreina
MA
Méndez
Roberto
R
Hornero
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000465:Algorithms; D001921:Brain / Q000502:physiology* / Q000503:physiopathology; D001927:Brain Diseases / Q000503:physiopathology; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009991:Oscillometry / Q000379:methods*; D012044:Regression Analysis; D012146:Rest / Q000502:physiology*; D012727:Sex Characteristics; D055815:Young Adult