Research Group 'Psychiatric Genetics', Head: Prof. Dr. Hans H. Stassen

Department of Psychiatry, Psychotherapy and Psychosomatics

Psychiatric Hospital, University of Zurich


Longterm Stability of EEG Spectral Patterns

Distinct Individuality

Under constant experimental conditions most EEG characteristics display a broad range of inter-individual differences, while being remarkably stable over time within subjects. Correlation coefficients are typically in the range of r=0.7-0.9 for repeated assessments at 14-day and 5-year intervals. Even a computerized recognition of persons by EEG spectral patterns has turned out to be possible at classification error rates of <5% for a random sample of 87 healthy subjects. Reports on the distinct individuality of human brain wave patterns date back to the very beginning of EEG research, when Travis and Gottlober published two articles entitled "Do brain waves have individuality" [1936] and "How consistent are an individual’s brain potentials from day to day?" [1937], and Davis and Davis published the first EEG twin study stating that the "within-pair differences of the resting EEG derived from monozygotic twins were not greater than the fluctuations within a single subject over time" [1936].

Trait-Like Qualities

All these findings suggest that EEG characteristics possess trait-like qualities which might be attributable to genetic predisposition. In fact, there is presumptive evidence from numerous studies on monozygotic and dizygotic twins, that the inter-individual variability of the human EEG under "normal" resting and sleep conditions is not just familial but heritable.

Continuous Phenotype Range

The variation of EEG characteristics forms a continuous, approximately normally distributed "phenotype range" rather than discrete phenotype classes, thus suggesting that the variation is quantitative and that the average phenotypic differences between genotypes may be small compared with the variation between individuals within genotypes. Inheritance was found not to follow simple Mendelian modes in the great majority of parameters used to quantify EEG characteristics.


Stassen HH, Bomben G, Propping P: Genetic aspects of the EEG: an investigation into the within-pair similarity of monozygotic and dizygotic twins with a new method of analysis. Electroenceph clin Neurophysiol 1987; 66: 489-501
Stassen HH, Lykken DT, Bomben G: The within-pair similarity of twins reared apart. Eur Arch Psychiatr Neurol Sci 1988; 237: 244-252
Stassen HH, Lykken DT, Propping P, Bomben G: Genetic determination of the human EEG (survey of recent results from twins reared together and apart). Human Genetics 1988; 80: 165-176
Stassen HH, Lykken DT, Propping P: Zwillingsuntersuchungen zur Genetik des normalen Elektroenzephalogramms. In: P. Baumann (ed): Biologische Psychiatrie der Gegenwart, Wien: Springer 1993, 139-144
Kaprio J, Buchsbaum M, Gottesman II, Heath A, Körner J, Kringlen E, McGuffin P, Propping P, Rietschel M, Stassen HH: What can twin studies contribute to the understanding of adult psychopathology? In: T.J. Bouchard jr. and P. Propping: Twins as a tool for behavioral genetics. Chichester: John Wiley & Sons, Dahlem Workshop Reports, Life Sciences Research Report 1993; 53: 287-299
Dünki RM, Schmid GB, Scheidegger P, Stassen HH, Bomben G, Propping P: Reliable computer-assisted classification of the EEG: EEG variants in index cases and their first-degree relatives. Am J Med Genetics B 1996; 67,1: 1-8
Stassen HH, Bomben G, Hell D: Familial brain wave patterns: study of a 12 sib family. Psychiat Genetics 1998; 8: 141-153
Stassen HH, Coppola R. Torrey EF, Gottesman II, Kuny S, Rickler KC, Hell D: EEG differences in monozygotic twins discordant and concordant for schizophrenia. Psychophysiology 1999; 36,1: 109-117
Dünki RM, Schmid GB, Stassen HH: Intraindividual specificity and stability of the human EEG: Linear vs. nonlinear approaches. Meth Inform Med 2000; 39: 78-82
Umbricht D, Koller R, Schmid L, Skrabo A, Grübel C, Huber T, Stassen HH: How specific are deficits in mismatch negativity generation to schizophrenia? Biol Psychiatry 2003; 53: 1120-1131
Stassen HH: EEG and evoked potentials. In: D. Cooper (ed) Nature Encyclopedia of the Human Genome. Nature Publishing Group, London 2003; 3: 266-269
Weisbrod M, Hill H, Sauer H, Niethammer R, Guggenbühl S, Stassen HH: Nongenetic pathologic developments of brain-wave patterns in monozygotic twins discordant and concordant for schizophrenia. Am J Med Genetics B 2004; 125: 1-9
Buckelmüller J, Landolt HP, Stassen HH, Achermann P: Trait-like individual differences in the human sleep EEG. Neuroscience 2006; 138: 351-356
EEG spectral pattern

Intra-individual stability of EEG spectral patterns: the upper half shows the pattern of the first measurement and the lower half shows the pattern of the second measurement 5 years later.
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