Resting EEG in psychosis and at-risk populations--a possible endophenotype?
BACKGROUND
Finding reliable endophenotypes for psychosis could lead to an improved understanding of aetiology, and provide useful alternative phenotypes for genetic association studies. Resting quantitative electroencephalography (QEEG) activity has been shown to be heritable and reliable over time. However, QEEG research in patients with psychosis has shown inconsistent and even contradictory findings, and studies of at-risk populations are scarce. Hence, this study aimed to investigate whether resting QEEG activity represents a candidate endophenotype for psychosis.


METHODS
QEEG activity at rest was compared in four frequency bands (delta, theta, alpha, and beta), between chronic patients with psychosis (N=48), first episode patients (N=46), at-risk populations ("at risk mental state", N=33; healthy relatives of patients, N=45), and healthy controls (N=107).


RESULTS
Results showed that chronic patients had significantly increased resting QEEG amplitudes in delta and theta frequencies compared to healthy controls. However, first episode patients and at-risk populations did not differ from controls in these frequency bands. There were no group differences in alpha or beta frequency bands.


CONCLUSIONS
Since no abnormalities were found in first episode patients, ARMS, or healthy relatives, resting QEEG activity in the frequency bands examined is unlikely to be related to genetic predisposition to psychosis. Rather than endophenotypes, the low frequency abnormalities observed in chronic patients are probably related to illness progression and/or to the long-term effects of treatments.
Mental Health Sciences Unit & Institute of Cognitive Neuroscience, University College London, W1W 7EJ, United Kingdom. Electronic address: s.ranlund@ucl.ac.uk.
Siri
S
Ranlund
NIHR Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, Kings College London, WC2R 2LS, United Kingdom.
Judith
J
Nottage
NIHR Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, Kings College London, WC2R 2LS, United Kingdom; Department of Psychology, Royal Holloway, University of London, TW20 0EX, United Kingdom.
Madiha
M
Shaikh
NIHR Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, Kings College London, WC2R 2LS, United Kingdom.
Anirban
A
Dutt
Psychiatry Department, Hospital Beatriz Ângelo, 2674-514 Loures, Lisbon, Portugal.
Miguel
M
Constante
Mental Health Sciences Unit & Institute of Cognitive Neuroscience, University College London, W1W 7EJ, United Kingdom; NIHR Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, Kings College London, WC2R 2LS, United Kingdom.
Muriel
M
Walshe
Psychology Research Laboratory, Harvard Medical School, McLean Hospital, Belmont, MA 02478, USA.
Mei-Hua
MH
Hall
The Wellcome Trust Centre for Neuroimaging, University College London, WC1N 3BG, United Kingdom.
Karl
K
Friston
NIHR Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, Kings College London, WC2R 2LS, United Kingdom.
Robin
R
Murray
Mental Health Sciences Unit & Institute of Cognitive Neuroscience, University College London, W1W 7EJ, United Kingdom; NIHR Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, Kings College London, WC2R 2LS, United Kingdom.
Elvira
E
Bramon
D000328:Adult; D058256:Brain Waves / Q000502:physiology*; D004569:Electroencephalography; D058068:Endophenotypes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000235:genetics* / Q000503:physiopathology*; D012146:Rest; D012306:Risk; D055815:Young Adult
At risk mental state; Electroencephalogram; Endophenotype; Psychosis; Resting EEG; Schizophrenia