Institute for Response-Genetics (e.V.)Chairman: Prof. Dr. Hans H. StassenPsychiatric Hospital (KPPP), University of Zurich |
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EEG Spectral Patterns of Monozygotic TwinsIt is a fact about monozygotic twins that their speaking voices are easily confusible, strikingly similar in pitch and timbre to an extent almost never found in siblings or in dizygotic twins. Now, the tonal qualities of the voice are largely determined by the shape and relative dimensions of the resonant cavities in the head and chest and by the size, musculature and innervation of the vocal cords. We can assume that the variability in most of the relevant components is under strong genetic control, so that twins make their vocal music with nearly identical instruments. The same holds true for brain waves, where we find strikingly similar patterns regardless of whether the co-twins were raised together or reared apart. Specifically, our studies revealed within-pair EEG similarities of the same order of magnitude (r=0.81) as one finds for EEG similarities computed from repeated assessments on the same individual under comparable experimental conditions (r=0.83). This within-pair similarity is contrasted by distinct inter-individual differences which enable nearly unambiguous identification of unrelated persons [Stassen 1988]. Twins Reared ApartWithin the scope of the "Minnesota Twin Study" [Bouchard TJ, Lykken DT, Heston L], monozygotic (MZ) and dizygotic (DZ) twins separated as infants and reared apart were invited to Minneapolis for a full week of study and testing. The mean age at separation was 4 months while the average age at reunion lay around 24 years. Our EEG analysis yielded comparably high within-pair MZ similarities (r=0.80) as in the sample of MZ twins brought up together. Continuous Phenotype RangeOur results suggested that EEG characteristics possess trait-like qualities which are clearly attributable to genetic predisposition. Heritability estimates, as derived from our twin data, lay in the range of 0.719-0.761 with the DZ/MZ ratio of EEG similarities being very close to the expected value of 0.5, thus supporting a polygenic additive mode of inheritance. References
Stassen HH, Bachmann S, Bridler R, Cattapan K, Herzig D, Schneeberger A, Seifritz E. Inflammatory
Processes linked to Major Depression and Schizophrenic Disorders and the Effects of Polypharmacy
in Psychiatry: Evidence from a longitudinal Study of 279 Patients under Therapy. Eur Arch
Psychiatry Clin Neurosci. 2021; 271(3): 507-520
[get the article]
Braun S, Bridler R, Müller N, Schwarz MJ, Seifritz E, Weisbrod M, Zgraggen A, Stassen HH:
Inflammatory Processes and Schizophrenia: Two Independent Lines of Evidence from a Study
of Twins Discordant and Concordant for Schizophrenic Disorders. Eur Arch Psychiatry Clin
Neurosci 2017; 267: 377-389
[get the article]
Braun S, Bridler R, Müller N, Schwarz MJ, Seifritz E, Weisbrod M, Zgraggen A, Stassen HH:
Inflammatory Processes and Schizophrenia: Two Independent Lines of Evidence From a Study
of Twins Discordant and Concordant for Schizophrenic Disorders. Neuropsychopharmacology
2016; 41: S414–S415
Stassen HH, Delfino JP, Kluckner VJ, Lott P, Mohr C: Vulnerabilität und psychische Erkrankung.
Swiss Archives of Neurology and Psychiatry 2014; 165(5): 152-157
Stassen HH, Angst J, Hell D, Scharfetter C, Szegedi A: Is there a common resilience mechanism
underlying antidepressant drug response? Evidence from 2'848 patients. J Clin Psychiatry 2007;
68(8): 1195-1205
Buckelmüller J, Landolt HP, Stassen HH, Achermann P: Trait-like individual differences in the
human sleep EEG. Neuroscience 2006; 138: 351-356
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
Stassen HH: EEG and evoked potentials. In: D. Cooper (ed) Nature Encyclopedia of the Human
Genome. Nature Publishing Group, London 2003; 3: 266-269
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
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
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
Stassen HH, Bomben G, Hell D: Familial brain wave patterns: study of a 12 sib family. Psychiat
Genetics 1998; 8: 141-153
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
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
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
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, Bomben G: The within-pair similarity of twins reared apart. Eur Arch
Psychiatr Neurol Sci 1988; 237: 244-252
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: The similarity approach to EEG analysis. Meth Inform Med 1985; 24: 200-212
Stassen HH: Computerized recognition of persons by EEG spectral patterns. Electroenceph
clin Neurophysiol 1980; 49: 190-194
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Pairs of MZ twins brought up together: the upper half shows the EEG spectral pattern of the first co-twin and the lower half the pattern of the second co-twin. |
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