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Sommer, Prof. Iris

Iris Sommer
Iris Sommer

Iris Sommer is Professor of Psychiatry at the University Medical Center Groningen. Sommer trained as a physician and psychiatrist, obtained her PhD cum laude in the field of schizophrenia, and founded the Stemmenpoli (Voices Clinic) at the UMC Utrecht. In 2017, her research on hallucinations ‘Zie ik spoken’ [Do I see ghosts?], was voted public research of the year.

Iris Sommer's pioneering work focuses, among other things, on the surprising fact that the female brain is much less well studied than the male brain. One of Sommer's key findings is that female hormones (such as estrogens) play a major protective role in psychotic disorders. While commonly prescribed antipsychotics actually appear to suppress the production of estrogens. With this important insight, Sommer has created new treatment guidelines for the care of women with psychotic disorders, and significantly improved the treatment prospects of female patients.

Unequal medical treatment between women and men is something that Iris Sommer advocates, because: 'by treating what is unequal as equal, you increase inequality.’ Health inequalities in psychiatric care are a major societal problem. It is Sommer's mission to rectify this. She is an international expert in neuropsychiatry. Her research addresses the origins of psychiatric disorders and the development of innovative treatments.

Current psychiatric treatments are mostly based on clinical studies in which women are underrepresented. This results in treatment for women being less evidence-based than for men, the consequences of which are significant. For instance, diagnoses in women are more delayed, and sometimes missed altogether. Furthermore, treatments are not as suitable, making women more likely to overdose and therefore have side effects. And menopause is not taken into account either.

Sommer wrote several books, including Haperende Hersenen [Faltering brains], a book in which she explains the origins, symptoms, diagnosis, and treatment of brain disorders in an accessible way, based on patients' personal experiences. In 2018, she published the book De Zeven Zintuigen [The seven senses]. The book is about how we perceive the world only partly with our senses and supplement the rest from our background.

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Publications

2022

Corona Hernández, H., Brederoo, S., de Boer, J., & Sommer, I. E. C. (2022). A data-driven linguistic characterization of hallucinated voices in clinical and non-clinical voice-hearers. Schizophrenia Research, 241, 210-217. https://doi.org/10.1016/j.schres.2022.01.055
Grandjean, E. L., van Zonneveld, S. M., Sommer, I. E. C., & Haarman, B. C. M. (2022). Anti-inflammatory dietary patterns to treat bipolar disorder? Journal of Affective Disorders, 311, 254-255. https://doi.org/10.1016/j.jad.2022.05.073
Sommer, I. E. C., Horowitz, M., Allott, K., Speyer, H., & Begemann, M. J. H. (2022). Antipsychotic maintenance treatment versus dose reduction: how the story continues. The Lancet Psychiatry, 9(8), 602-603. https://doi.org/10.1016/S2215-0366(22)00230-9
Brand, B. A., Haveman, Y. R. A., De Beer, F., De Boer, J. N., Dazzan, P., & Sommer, I. E. C. (2022). Antipsychotic medication for women with schizophrenia spectrum disorders. Psychological Medicine, 52(4), 649 - 663. https://doi.org/10.1017/S0033291721004591
Corona Hernández, H., de Boer, J., Brederoo, S., Voppel, A., & Sommer, I. E. C. (2022). Assessing coherence through linguistic connectives: Analysis of speech in patients with schizophrenia-spectrum disorders. Schizophrenia Research. https://doi.org/10.1016/j.schres.2022.06.013
de Rijke, T. J., Doting, M. H. E., van Hemert, S., De Deyn, P. P., van Munster, B. C., Harmsen, H. J. M., & Sommer, I. E. C. (2022). A Systematic Review on the Effects of Different Types of Probiotics in Animal Alzheimer's Disease Studies. Frontiers in Psychiatry, 13, [879491]. https://doi.org/10.3389/fpsyt.2022.879491
Puvogel, S., Palma, V., & Sommer, I. E. C. (2022). Brain vasculature disturbance in schizophrenia. Current opinion in psychiatry. https://doi.org/10.1097/YCO.0000000000000789
Oomen, P. P., de Boer, J. N., Brederoo, S. G., Voppel, A. E., Brand, B. A., Wijnen, F. N. K., & Sommer, I. E. C. (2022). Characterizing speech heterogeneity in schizophrenia-spectrum disorders. Journal of psychopathology and clinical science, 131(2), 172-181. https://doi.org/10.1037/abn0000736
Zaki, J. K., Lago, S. G., Rustogi, N., Gangadin, S. S., Benacek, J., van Rees, G. F., Haenisch, F., Broek, J. A., Suarez-Pinilla, P., Ruland, T., Auyeung, B., Mikova, O., Kabacs, N., Arolt, V., Baron-Cohen, S., Crespo-Facorro, B., Drexhage, H. A., de Witte, L. D., Kahn, R. S., ... Tomasik, J. (2022). Diagnostic model development for schizophrenia based on peripheral blood mononuclear cell subtype-specific expression of metabolic markers. Translational Psychiatry, 12, [457]. https://doi.org/10.1038/s41398-022-02229-w
Adam, O., Blay, M., Brunoni, A. R., Chang, H-A., Gomes, J. S., Javitt, D. C., Jung, D-U., Kantrowitz, J. T., Koops, S., Lindenmayer, J-P., Palm, U., Smith, R. C., Sommer, I. E., Lane Valiengo, L. D. C., Weickert, T. W., Brunelin, J., & Mondino, M. (2022). Efficacy of Transcranial Direct Current Stimulation to Improve Insight in Patients With Schizophrenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Schizophrenia Bulletin. https://doi.org/10.1093/schbul/sbac078
Aichholzer, M., Gangadin, S. S., Sommer, I. E. C., Wijkhuis, A., de Witte, L. D., Kahn, R. S., Bahn, S., Drexhage, H. A., & Schiweck, C. (2022). Inflammatory monocyte gene signature predicts beneficial within group effect of simvastatin in patients with schizophrenia spectrum disorders in a secondary analysis of a randomized controlled trial. Brain, Behavior, and Immunity - Health, 26, [100551]. https://doi.org/10.1016/j.bbih.2022.100551
Schutte, M. J. L., Voppel, A., Collin, G., Abramovic, L., Boks, M. P. M., Cahn, W., van Haren, N. E. M., Hugdahl, K., Koops, S., Mandl, R. C. W., & Sommer, I. E. C. (2022). Modular-Level Functional Connectome Alterations in Individuals With Hallucinations Across the Psychosis Continuum. Schizophrenia Bulletin, 48(3), 684–694. https://doi.org/10.1093/schbul/sbac007
Hugdahl, K., Craven, A. R., Johnsen, E., Ersland, L., Stoyanov, D., Kandilarova, S., Sandoy, L. B., Kroken, R. A., Loberg, E-M., & Sommer, I. E. (2022). Neural Activation in the Ventromedial Prefrontal Cortex Precedes Conscious Experience of Being in or Out of a Transient Hallucinatory State. Schizophrenia Bulletin, [sbac028]. https://doi.org/10.1093/schbul/sbac028
Linszen, M. M. J., de Boer, J. N., Schutte, M. J. L., Begemann, M. J. H., de Vries, J., Koops, S., Blom, R. E., Bohlken, M. M., Heringa, S. M., Blom, J. D., & Sommer, I. E. C. (2022). Occurrence and phenomenology of hallucinations in the general population: A large online survey. Schizophrenia, 8, [41]. https://doi.org/10.1038/s41537-022-00229-9
Solmi, M., Estrade, A., Thompson, T., Agorastos, A., Radua, J., Cortese, S., Dragioti, E., Leisch, F., Vancampfort, D., Thygesen, L. C., Aschauer, H., Schloegelhofer, M., Akimova, E., Schneeberger, A., Huber, C. G., Hasler, G., Conus, P., Do Cuenod, K. Q., von Kanel, R., ... Sommer, I. (2022). Physical and mental health impact of COVID-19 on children, adolescents, and their families: The Collaborative Outcomes study on Health and Functioning during Infection Times-Children and Adolescents (COH-FIT-C&A). Journal of Affective Disorders, 299, 367-376. https://doi.org/10.1016/j.jad.2021.09.090
Sommer, I. E. C., & DeLisi, L. E. (2022). Precision psychiatry and the clinical care for people with schizophrenia: sex, race and ethnicity in relation to social determinants of mental health. Current opinion in psychiatry, 35(3), 137-139. https://doi.org/10.1097/YCO.0000000000000781
Yehya, A., Khaled, S. M., Sommer, I. E. C., Woodruff, P., & Daher-Nashif, S. (2022). Psychotic-like experiences among university female students in Qatar: A qualitative-phenomenological study. Frontiers in Psychiatry, 13, [988913]. https://doi.org/10.3389/fpsyt.2022.988913
Grootens, K. P., & Sommer, I. E. (2022). Redesigning phase 3 and 4 trials to adopt shared decision making. The Lancet. Psychiatry, 9(2), 101-103. https://doi.org/10.1016/S2215-0366(21)00385-0
Borkent, J., Ioannou, M., Laman, J. D., Haarman, B. C. M., & Sommer, I. E. C. (2022). Role of the gut microbiome in three major psychiatric disorders. Psychological Medicine, 52(7), 1222-1242. [0033291722000897]. https://doi.org/10.1017/S0033291722000897
Puvogel, S., Alsema, A., Kracht, L., Webster, M. J., Weickert, C. S., Sommer, I. E. C., & Eggen, B. J. L. (2022). Single-nucleus RNA sequencing of midbrain blood-brain barrier cells in schizophrenia reveals subtle transcriptional changes with overall preservation of cellular proportions and phenotypes. Molecular Psychiatry. https://doi.org/10.1038/s41380-022-01796-0
Horowitz, M. A., Moncrieff, J., de Haan, L., Bogers, J. P. A. M., Gangadin, S. S., Kikkert, M., Veling, W., & Sommer, I. E. C. (2022). Tapering antipsychotic medication: practical considerations. Psychological Medicine, 52(1), 32-35. https://doi.org/10.1017/S0033291721003299
Solmi, M., Estrade, A., Thompson, T., Agorastos, A., Radua, J., Cortese, S., Dragioti, E., Leisch, F., Vancampfort, D., Thygesen, L. C., Aschauer, H., Schloegelhofer, M., Akimova, E., Schneeberger, A., Huber, C. G., Hasler, G., Conus, P., Do Cuenod, K. Q., von Kanel, R., ... Sommer, I. (2022). The collaborative outcomes study on health and functioning during infection times in adults (COH-FIT-Adults): Design and methods of an international online survey targeting physical and mental health effects of the COVID-19 pandemic. Journal of Affective Disorders, 299, 393-407. https://doi.org/10.1016/j.jad.2021.07.048
Oomen, P. P., Gangadin, S. S., Begemann, M. J. H., Visser, E., Mandl, R. C. W., & Sommer, I. E. C. (2022). The neurobiological characterization of distinct cognitive subtypes in early-phase schizophrenia-spectrum disorders. Schizophrenia Research, 241, 228-237. https://doi.org/10.1016/j.schres.2022.02.006
Brand, B. A., de Boer, J. N., Dazzan, P., & Sommer, I. E. (2022). Towards better care for women with schizophrenia-spectrum disorders. The Lancet. Psychiatry, 9(4), 330-336. https://doi.org/10.1016/S2215-0366(21)00383-7
van Zonneveld, S. M., Haarman, B. C. M., van den Oever, E. J., Nuninga, J. O., & Sommer, I. E. C. (2022). Unhealthy diet in schizophrenia spectrum disorders. Current opinion in psychiatry, 35(3), 177-185. https://doi.org/10.1097/YCO.0000000000000791
Sommer, I. E., Brand, B. A., Gangadin, S., Tanskanen, A., Tiihonen, J., & Taipale, H. (2022). Women with Schizophrenia-Spectrum Disorders After Menopause: A Vulnerable Group for Relapse. Schizophrenia Bulletin, [sbac139]. https://doi.org/10.1093/schbul/sbac139

2021

Begemann, M. J. H., Sommer, I. E., Brand, R. M., Oomen, P. P., Jongeneel, A., Berkhout, J., Molenaar, R. E., Wielage, N. N., Toh, W. L., Rossell, S. L., & Bell, I. H. (2022). Auditory verbal hallucinations and childhood trauma subtypes across the psychosis continuum: a cluster analysis. Cognitive Neuropsychiatry, 27(2-3). https://doi.org/10.1080/13546805.2021.1925235
Kirschner, M., Hodzic-Santor, B., Antoniades, M., Nenadic, I., Kircher, T., Krug, A., Meller, T., Grotegerd, D., Fornito, A., Arnatkeviciute, A., Bellgrove, M. A., Tiego, J., Dannlowski, U., Koch, K., Hülsmann, C., Kugel, H., Enneking, V., Klug, M., Leehr, E. J., ... Modinos, G. (2022). Cortical and subcortical neuroanatomical signatures of schizotypy in 3004 individuals assessed in a worldwide ENIGMA study. Molecular Psychiatry, 27, 1167–1176. https://doi.org/10.1038/s41380-021-01359-9
Luykx, J. J., Loef, D., Lin, B., van Diermen, L., Nuninga, J. O., van Exel, E., Oudega, M. L., Rhebergen, D., Schouws, S. N. T. M., van Eijndhoven, P., Verwijk, E., Schrijvers, D., Birkenhager, T. K., Ryan, K. M., Arts, B., van Bronswijk, S. C., Kenis, G., Schurgers, G., Baune, B. T., ... Rutten, B. P. F. (2022). Interrogating Associations Between Polygenic Liabilities and Electroconvulsive Therapy Effectiveness. Biological Psychiatry, 91(6), 531-539. https://doi.org/10.1016/j.biopsych.2021.10.013
Jansma, J., Essen, R. V., Haarman, B. C. M., Chatziioannou, A. C., Borkent, J., Ioannou, M., Hemert, S. V., Sommer, I. E. C., & Aidy, S. E. (2022). Metabolic phenotyping reveals a potential link between elevated faecal amino acids, diet and symptom severity in individuals with severe mental illness. Journal of Psychiatric Research, 151, 507-515. https://doi.org/10.1101/2021.12.01.21267133, https://doi.org/10.1016/j.jpsychires.2022.05.011
Hjelmervik, H., Craven, A. R., Johnsen, E., Kompus, K., Bless, J. J., Sinkeviciute, I., Kroken, R. A., Løberg, E. M., Ersland, L., Grüner, R., Sommer, I. E., & Hugdahl, K. (2022). Negative valence of hallucinatory voices as predictor of cortical glutamatergic metabolite levels in schizophrenia patients. Brain and Behavior, 12(1), [e2446]. https://doi.org/10.1002/brb3.2446
Germann, M., Brederoo, S. G., & Sommer, I. E. C. (2021). Abnormal synaptic pruning during adolescence underlying the development of psychotic disorders. Current opinion in psychiatry, 34(3), 222-227. https://doi.org/10.1097/YCO.0000000000000696
de Boer, J. N., Voppel, A. E., Brederoo, S. G., Schnack, H. G., Truong, K. P., Wijnen, F. N. K., & Sommer, I. E. C. (2021). Acoustic speech markers for schizophrenia-spectrum disorders: a diagnostic and symptom-recognition tool. Psychological Medicine, 1-11. https://doi.org/10.1017/S0033291721002804
Schutte, M. J. L., Bohlken, M. M., Collin, G., Abramovic, L., Boks, M. P. M., Cahn, W., Dauwan, M., van Dellen, E., van Haren, N. E. M., Hugdahl, K., Koops, S., Mandl, R. C. W., & Sommer, I. E. C. (2021). Author Correction: Functional connectome differences in individuals with hallucinations across the psychosis continuum (Scientific Reports, (2021), 11, 1, (1108), 10.1038/s41598-020-80657-8). Scientific Reports, 11, [8540]. https://doi.org/10.1038/s41598-021-87849-w
Barbosa, S., Martinuzzi, E., Sommer, I. E., Dazzan, P., McGuire, P., Arango, C., Diaz-Caneja, C. M., Fleischhacker, W. W., Rujescu, D., Glenthøj, B., Winter-Van Rossum, I., Kahn, R. S., Yolken, R., Lewis, S., Drake, R., Leucht, S., Gilet, C., Khalfallah, O., Davidovic, L., ... Glaichenhaus, N. (2021). Baseline Levels of C-Reactive Protein and Proinflammatory Cytokines Are Not Associated with Early Response to Amisulpride in Patients with First Episode Psychosis: The OPTiMiSE Cohort Study. Schizophrenia Bulletin Open, 2(1), [sgab017]. https://doi.org/10.1093/schizbullopen/sgab017
Begemann, M. J. H., Schutte, M. J. L., Van Dellen, E., Abramovic, L., Boks, M. P., Van Haren, N. E. M., Mandl, R. C. W., Vinkers, C. H., Bohlken, M. M., & Sommer, I. E. C. (2021). Childhood trauma is associated with reduced frontal gray matter volume: A large transdiagnostic structural MRI study. Psychological Medicine. https://doi.org/10.1017/S0033291721002087
Nuninga, J. O., Mandl, R. C. W., & Sommer, I. E. C. (2021). Clinical Relevance of Brain Changes After Electroconvulsive Therapy: Is There Really No Link at All? Biological Psychiatry, 89(4), e13-e14. https://doi.org/10.1016/j.biopsych.2020.04.030
Nuninga, J. O., Mandl, R. C. W., & Sommer, I. E. C. (2021). Correction: The dentate gyrus in depression: directions for future research (Molecular Psychiatry, (2021), 26, 6, (1720-1722), 10.1038/s41380-020-0678-8). Molecular Psychiatry, 26(6), 2677. https://doi.org/10.1038/s41380-020-0712-x
Karolinska Schizophrenia Project K, Frangou, S., Modabbernia, A., Williams, S. C. R., Papachristou, E., Doucet, G. E., Agartz, I., Aghajani, M., Akudjedu, T. N., Albajes-Eizagirre, A., Alnaes, D., Alpert, K., Andersson, M., Andreasen, N. C., Andreassen, O. A., Asherson, P., Banaschewski, T., Bargallo, N., Baumeister, S., ... Wang, L. (2021). Cortical thickness across the lifespan: Data from 17,075 healthy individuals aged 3-90 years. Human brain mapping. https://doi.org/10.1002/hbm.25364
DeLisi, L. E., & Sommer, I. E. C. (2021). Editorial: Racial and ethnic disparities in research and treatment of people with schizophrenia. Current opinion in psychiatry, 34(3), 199-202. https://doi.org/10.1097/YCO.0000000000000691
Brand, B. A., de Boer, J. N., & Sommer, I. E. C. (2021). Estrogens in schizophrenia: progress, current challenges and opportunities. Current opinion in psychiatry, 34(3), 228-237. https://doi.org/10.1097/YCO.0000000000000699
Brederoo, S. G., de Boer, J. N., De Vries, J., Linszen, M. M. J., & Sommer, I. E. C. (2021). Fragmented sleep relates to hallucinations across perceptual modalities in the general population. Scientific Reports, 11(1), [7735]. https://doi.org/10.1038/s41598-021-87318-4
Schutte, M. J. L., Bohlken, M. M., Collin, G., Abramovic, L., Boks, M. P. M., Cahn, W., Dauwan, M., van Dellen, E., van Haren, N. E. M., Hugdahl, K., Koops, S., Mandl, R. C. W., & Sommer, I. E. C. (2021). Functional connectome differences in individuals with hallucinations across the psychosis continuum. Scientific Reports, 11(1), [1108]. https://doi.org/10.1038/s41598-020-80657-8
Liu, X., Eickhoff, S. B., Caspers, S., Wu, J., Genon, S., Hoffstaedter, F., Mars, R. B., Sommer, I. E., Eickhoff, C. R., Chen, J., Jardri, R., Reetz, K., Dogan, I., Aleman, A., Kogler, L., Gruber, O., Caspers, J., Mathys, C., & Patil, K. R. (2021). Functional parcellation of human and macaque striatum reveals human-specific connectivity in the dorsal caudate. Neuroimage, 235, [118006]. https://doi.org/10.1016/j.neuroimage.2021.118006, https://doi.org/10.1016/j.neuroimage.2021.118006
Berk, M., Leboyer, M., & Sommer, I. E. C. (2021). Immuno-Psychiatry: Facts and Prospects . Springer. https://doi.org/10.1007/978-3-030-71229-7
Brederoo, S. G., Nadema, F. G., Goedhart, F. G., Voppel, A. E., De Boer, J. N., Wouts, J., Koops, S., & Sommer, I. E. C. (2021). Implementation of automatic speech analysis for early detection of psychiatric symptoms: What do patients want? Journal of Psychiatric Research, 142, 299-301. https://doi.org/10.1016/j.jpsychires.2021.08.019
Chen, J., Mueller, V., Dukart, J., Hoffstaedter, F., Baker, J. T., Holmes, A. J., Vatansever, D., Nickl-Jockschat, T., Liu, X., Derntl, B., Kogler, L., Jardri, R., Gruber, O., Aleman, A., Sommer, I. E., Eickhoff, S. B., & Patil, K. R. (2021). Intrinsic Connectivity Patterns of Task-Defined Brain Networks Allow Individual Prediction of Cognitive Symptom Dimension of Schizophrenia and Are Linked to Molecular Architecture. Biological Psychiatry, 89(3), 308-319. https://doi.org/10.1016/j.biopsych.2020.09.024
Oomen, P. P., Begemann, M. J. H., Brand, B. A., de Haan, L., Veling, W., Koops, S., van Os, J., Smit, F., Bakker, P. R., van Beveren, N., Boonstra, N., Gülöksüz, S., Kikkert, M., Lokkerbol, J., Marcelis, M., Rosema, B-S., de Beer, F., Gangadin, S. S., Geraets, C. N. W., ... Sommer, I. E. C. (2021). Longitudinal clinical and functional outcome in distinct cognitive subgroups of first-episode psychosis: a cluster analysis. Psychological Medicine, 1-11. https://doi.org/10.1017/S0033291721004153
Kusztrits, I., Laroi, F., Laloyaux, J., Marquardt, L., Sinkeviciute, I., Kjelby, E., Johnsen, E., Sommer, I. E., Hugdahl, K., & Hirnstein, M. (2021). Mapping psychotic-like experiences: Results from an online survey. Scandinavian Journal of Psychology, 62(2), 237-248. https://doi.org/10.1111/sjop.12683
HAMLETT OPHELIA Consortium, Kikkert, M. J., Veling, W., de Haan, L., Begemann, M. J. H., de Koning, M., & Sommer, I. E. (2021). Medication strategies in first episode psychosis patients: A survey among psychiatrists. Early intervention in psychiatry. https://doi.org/10.1111/eip.13138
So, S. H., Chung, L. K., Tse, C-Y., Chan, S. S., Chong, G. H., Hung, K. S., & Sommer, I. E. C. (2021). Moment-to-moment dynamics between auditory verbal hallucinations and negative affect and the role of beliefs about voices. Psychological Medicine, 51(4), 661-667. https://doi.org/10.1017/S0033291719003611
de Boer, J., Corona Hernández, H., Gerritse, F., Brederoo, S., Wijnen, F., & Sommer, I. E. C. (2021). Negative content in auditory verbal hallucinations: a natural language processing approach. Cognitive Neuropsychiatry. https://doi.org/10.1080/13546805.2021.1941831
Chen, J., Wensing, T., Hoffstaedter, F., Cieslik, E. C., Muller, V., Patil, K. R., Aleman, A., Derntl, B., Gruber, O., Jardri, R., Kogler, L., Sommer, I. E., Eickhoff, S. B., & Nickl-Jockschat, T. (2021). Neurobiological substrates of the positive formal thought disorder in schizophrenia revealed by seed connectome-based predictive modeling. NeuroImage. Clinical, 30, [102666]. https://doi.org/10.1016/j.nicl.2021.102666
Dierckx, R., Otte, A., de Vries, E. F., van Waarde, A., & Sommer, I. E. C. (Eds.) (2021). PET and SPECT in Psychiatry (Second Edition). (2 ed.) Springer Nature. https://doi.org/10.1007/978-3-030-57231-0
Voppel, A. E., de Boer, J. N., Brederoo, S. G., Schnack, H. G., & Sommer, I. E. C. (2021). Quantified language connectedness in schizophrenia-spectrum disorders. Psychiatry Research, 304, [114130]. https://doi.org/10.1016/j.psychres.2021.114130
Faay, M. D. M., & Sommer, I. E. (2021). Risk and Prevention of Aggression in Patients With Psychotic Disorders. American Journal of Psychiatry, 178(3), 218-220. https://doi.org/10.1176/appi.ajp.2020.21010035
Hoekstra, S., Bartz-Johannessen, C., Sinkeviciute, I., Reitan, S. K., Kroken, R. A., Loberg, E-M., Larsen, T. K., Rettenbacher, M., Johnsen, E., & Sommer, I. E. (2021). Sex differences in antipsychotic efficacy and side effects in schizophrenia spectrum disorder: results from the BeSt InTro study. NPJ Schizophrenia, 7(1), [39]. https://doi.org/10.1038/s41537-021-00170-3
Nuninga, J. O., Mandl, R. C. W., Siero, J., Nieuwdorp, W., Heringa, S. M., Boks, M. P., Somers, M., & Sommer, I. E. C. (2021). Shape and volume changes of the superior lateral ventricle after electroconvulsive therapy measured with ultra-high field MRI. Psychiatry research-Neuroimaging, 317, [111384]. https://doi.org/10.1016/j.pscychresns.2021.111384
Sommer, I. E., Gangadin, S. S., de Witte, L. D., Koops, S., van Baal, C., Bahn, S., Drexhage, H., van Haren, N. E. M., Veling, W., Bruggeman, R., Martens, P., Wiersma, S., Veerman, S. R. T., Grootens, K. P., van Beveren, N., Kahn, R. S., & Begemann, M. J. H. (2021). Simvastatin Augmentation for Patients With Early-Phase Schizophrenia-Spectrum Disorders: A Double-Blind, Randomized Placebo-Controlled Trial. Schizophrenia Bulletin, 47(4), 1108–1115. https://doi.org/10.1093/schbul/sbab010
Koops, S., Brederoo, S. G., de Boer, J. N., Nadema, F. G., Voppel, A. E., & Sommer, I. E. (2021). Speech as a Biomarker for Depression. Cns & neurological disorders-Drug targets. https://doi.org/10.2174/1871527320666211213125847
Marschall, T. M., Ćurčić-Blake, B., Brederoo, S. G., Renken, R. J., Linszen, M. M. J., Koops, S., & Sommer, I. E. C. (2021). Spontaneous brain activity underlying auditory hallucinations in the hearing-impaired. Cortex, 136, 1-13. https://doi.org/10.1016/j.cortex.2020.12.005
Karolinska Schizophrenia Project K, Dima, D., Modabbernia, A., Papachristou, E., Doucet, G. E., Agartz, I., Aghajani, M., Akudjedu, T. N., Albajes-Eizagirre, A., Alnaes, D., Alpert, K., Andersson, M., Andreasen, N. C., Andreassen, O. A., Asherson, P., Banaschewski, T., Bargallo, N., Baumeister, S., Baur-Streubel, R., ... Wang, L. (2021). Subcortical volumes across the lifespan: Data from 18,605 healthy individuals aged 3-90 years. Human brain mapping. https://doi.org/10.1002/hbm.25320
OPTIMISE Study Grp, Dazzan, P., Lawrence, A. J., Reinders, A. A. T. S., Egerton, A., van Haren, N. E. M., Merritt, K., Barker, G. J., Perez-Iglesias, R., Sendt, K-V., Demjaha, A., Nam, K. W., Sommer, I. E., Pantelis, C., Fleischhacker, W. W., van Rossum, I. W., Galderisi, S., Mucci, A., Drake, R., ... McGuire, P. (2021). Symptom Remission and Brain Cortical Networks at First Clinical Presentation of Psychosis: The OPTiMiSE Study. Schizophrenia Bulletin, 47(2), 444-455. https://doi.org/10.1093/schbul/sbaa115
Nuninga, J. O., & Sommer, I. E. C. (2021). The Dentate Gyrus: Its Value for Depression. Biological psychiatry. Cognitive neuroscience and neuroimaging, 6(1), 6-7. https://doi.org/10.1016/j.bpsc.2020.10.016
Guerrin, C. G. J., Doorduin, J., Sommer, I. E., & de Vries, E. F. J. (2021). The dual hit hypothesis of schizophrenia: evidence from animal models. Neuroscience and Biobehavioral Reviews, 131, 1150-1168. https://doi.org/10.1016/j.neubiorev.2021.10.025
Nasib, L. G., Gangadin, S. S., Rossum, I. W., Boudewijns, Z. S. R. M., de Witte, L. D., Wilting, I., Luykx, J., Somers, M., Veen, N., van Baal, C., Kahn, R. S., & Sommer, I. E. (2021). The effect of prednisolone on symptom severity in schizophrenia: A placebo-controlled, randomized controlled trial. Schizophrenia Research, 230, 79-86. https://doi.org/10.1016/j.schres.2021.01.024
Fraguas, D., Diaz-Caneja, C. M., Pina-Camacho, L., Rossum, I. W. V., Baandrup, L., Sommer, I. E., Glenthoj, B., Kahn, R. S., Leucht, S., & Arango, C. (2021). The role of depression in the prediction of a "late" remission in first-episode psychosis: An analysis of the OPTiMiSE study. Schizophrenia Research, 231, 100-107. https://doi.org/10.1016/j.schres.2021.03.010

2020

Karolinska Schizophrenia Project (KaSP) consortium, Wierenga, L. M., Doucet, G. E., Dima, D., Agartz, I., Aghajani, M., Akudjedu, T. N., Albajes-Eizagirre, A., Alnaes, D., Alpert, K. I., Andreassen, O. A., Anticevic, A., Asherson, P., Banaschewski, T., Bargallo, N., Baumeister, S., Baur-Streubel, R., Bertolino, A., Bonvino, A., ... Wang, L. (2022). Greater male than female variability in regional brain structure across the lifespan. Human brain mapping, 43(1), 470-499. https://doi.org/10.1002/hbm.25204
Aleman, A., & Sommer, I. (2022). The silent danger of social distancing. Psychological Medicine, 52(4), 789-790. https://doi.org/10.1017/S0033291720002597
van der Zalm, Y., Foldager, L., Termorshuizen, F., Sommer, I. E., Nielsen, J., & Selten, J-P. (2021). Clozapine and mortality: A comparison with other antipsychotics in a nationwide Danish cohort study. Acta Psychiatrica Scandinavica, 143(3), 216-226. https://doi.org/10.1111/acps.13267
Jagesar, R. R., Roozen, M. C., van der Heijden, I., Ikani, N., Tyborowska, A., Penninx, B. W. J. H., Ruhe, H. G., Sommer, I. E. C., Kas, M. J., & Vorstman, J. A. S. (2021). Digital phenotyping and the COVID-19 pandemic: Capturing behavioral change in patients with psychiatric disorders. European Neuropsychopharmacology, 42, 115-120. https://doi.org/10.1016/j.euroneuro.2020.11.012
Wagner, E., Honer, W. G., Sommer, I. E., Koops, S., Blumberger, D. M., Daskalakis, Z. J., Dlabac-De Lange, J. J., Bais, L., Knegtering, H., Aleman, A., Novak, T., Klirova, M., Slotema, C., Brunelin, J., Poulet, E., Kujovic, M., Cordes, J., Wobrock, T., Siskind, D., ... Hasan, A. (2021). Repetitive transcranial magnetic stimulation (rTMS) for schizophrenia patients treated with clozapine. World journal of biological psychiatry, 22(1), 14-26. https://doi.org/10.1080/15622975.2020.1733080
Ioannou, M., Foiselle, M., Mallet, J., Stam, E. L., Godin, O., Dubertret, C., Terro, E., Sommer, I. E. C., Haarman, B. C. M., Leboyer, M., & Schoevers, R. A. (2021). Towards precision medicine: What are the stratification hypotheses to identify homogeneous inflammatory subgroups. European Neuropsychopharmacology, 45, 108-121. https://doi.org/10.1016/j.euroneuro.2020.11.001
Geng, H., Xu, P., Sommer, I. E., Luo, Y-J., Aleman, A., & Curcic-Blake, B. (2020). Abnormal dynamic resting-state brain network organization in auditory verbal hallucination. Brain Structure and Function, 225(8), 2315-2330. https://doi.org/10.1007/s00429-020-02119-1
Ormel, P. R., Boettcher, C., Gigase, F. A. J., Missall, R. D., van Zuiden, W., Zapata, M. C. F., Ilhan, D., de Goeij, M., Udine, E., Sommer, I. E. C., Priller, J., Raj, T., Kahn, R. S., Hol, E. M., & de Witte, L. D. (2020). A characterization of the molecular phenotype and inflammatory response of schizophrenia patient-derived microglia-like cells. Brain behavior and immunity, 90, 196-207. https://doi.org/10.1016/j.bbi.2020.08.012
Jongs, N., Jagesar, R., van Haren, N. E. M., Penninx, B. W. J. H., Reus, L., Visser, P. J., van der Wee, N. J. A., Koning, I. M., Arango, C., Sommer, I. E. C., Eijkemans, M. J. C., Vorstman, J. A., & Kas, M. J. (2020). A framework for assessing neuropsychiatric phenotypes by using smartphone-based location data. Translational Psychiatry, 10(1), [211]. https://doi.org/10.1038/s41398-020-00893-4
de Boer, J. N., Brederoo, S. G., Voppel, A. E., & Sommer, I. E. C. (2020). Anomalies in language as a biomarker for schizophrenia. Current opinion in psychiatry, 33(3), 212-218. https://doi.org/10.1097/YCO.0000000000000595
Marschall, T. M., Brederoo, S. G., Ćurčić-Blake, B., & Sommer, I. E. C. (2020). Deafferentation as a cause of hallucinations. Current opinion in psychiatry, 33(3), 206-211. https://doi.org/10.1097/YCO.0000000000000586
CLOZ-NP Study Grp, van der Zalm, Y. C., Schulte, P. F., Bogers, J. P. A. M., Termorshuizen, F., Marcelis, M., van Piere, M. A. G. B., Sommer, I. E., & Selten, J. P. (2020). Delegating Clozapine Monitoring to Advanced Nurse Practitioners: An Exploratory, Randomized Study to Assess the Effect on Prescription and Its Safety. Administration and Policy in Mental Health and Mental Health Services Research , 47(4), 632-640. https://doi.org/10.1007/s10488-020-01031-4
Speyer, H., Begemann, M., Albert, N., Weller, A., Nordentoft, M., Veling, W., Sommer, I. E., Allott, K., & Killackey, E. (2020). Discontinuation of antipsychotic medication-time to rethink trial design. The Lancet. Psychiatry, 7(10), 841-842. https://doi.org/10.1016/S2215-0366(20)30340-0
Thompson, I. A., de Vries, E. F. J., & Sommer, I. E. C. (2020). Dopamine D-2 up-regulation in psychosis patients after antipsychotic drug treatment. Current opinion in psychiatry, 33(3), 200-205. https://doi.org/10.1097/YCO.0000000000000598
Fernando, P., Sommer, I. E. C., & Hasan, A. (2020). Do we need sex-oriented clinical practice guidelines for the treatment of schizophrenia? Current opinion in psychiatry, 33(3), 192-199. https://doi.org/10.1097/YCO.0000000000000597
Begemann, M., Leon, M., van der Horn, H. J., van der Naalt, J., & Sommer, I. (2020). Drugs with anti-inflammatory effects to improve outcome of traumatic brain injury: a meta-analysis. Scientific Reports, 10(1), 1-10. [16179]. https://doi.org/10.1038/s41598-020-73227-5
Marschall, T., Curcic-Blake, B., Brederoo, S., & Sommer, I. (2020). DYNAMIC FUNCTIONAL NETWORK CONNECTIVITY COMPARING AUDITORY VERBAL HALLUCINATIONS IN PSYCHOTIC AND NON-PSYCHOTIC SUBJECTS. Schizophrenia Bulletin, 46(S1), S97-S97. [S161]. https://doi.org/10.1093/schbul/sbaa031.227
Eltokhi, A., Janmaat, I. E., Genedi, M., Haarman, B. C. M., & Sommer, I. E. C. (2020). Dysregulation of synaptic pruning as a possible link between intestinal microbiota dysbiosis and neuropsychiatric disorders. Journal of Neuroscience Research, 98(7), 1335-1369. https://doi.org/10.1002/jnr.24616
Begemann, M. J., Brand, B. A., Ćurčić-Blake, B., Aleman, A., & Sommer, I. E. (2020). Efficacy of non-invasive brain stimulation on cognitive functioning in brain disorders: a meta-analysis. Psychological Medicine, 50(15), 2465-2486. [0033291720003670]. https://doi.org/10.1017/S0033291720003670
van Dellen, E., Borner, C., Schutte, M., van Montfort, S., Abramovic, L., Boks, M. P., Cahn, W., van Haren, N., Mandl, R., Stam, C. J., & Sommer, I. (2020). Functional brain networks in the schizophrenia spectrum and bipolar disorder with psychosis. NPJ Schizophrenia, 6(1), [22]. https://doi.org/10.1038/s41537-020-00111-6
ENIGMA Consortium, Hofer, E., Roshchupkin, G. V., Adams, H. H. H., Knol, M. J., Lin, H., Li, S., Zare, H., Ahmad, S., Armstrong, N. J., Satizabal, C. L., Bernard, M., Bis, J. C., Gillespie, N. A., Luciano, M., Mishra, A., Scholz, M., Teumer, A., Xia, R., ... Trollor, J. (2020). Genetic correlations and genome-wide associations of cortical structure in general population samples of 22,824 adults. Nature Communications, 11(1), [4796]. https://doi.org/10.1038/s41467-020-18367-y
Ottens, T. H., Sommer, I. E. C., Begemann, M. J., Schutte, M., Cramer, M. J., Suyker, W. J., Van Dijk, D., & Slooter, A. J. C. (2020). Hallucinations after Cardiac Surgery: A Prospective Observational Study. Medicina-Lithuania, 56(3), [104]. https://doi.org/10.3390/medicina56030104
Schutte, M. J. L., Linszen, M. M. J., Marschall, T. M., ffytche, D. H., Koops, S., van Dellen, E., Heringa, S. M., Slooter, A. J. C., Teunisse, R., van den Heuvel, O. A., Lemstra, A. W., Foncke, E. M. J., Slotema, C. W., de Jong, J., Rossell, S. L., & Sommer, I. E. C. (2020). Hallucinations and other psychotic experiences across diagnoses: A comparison of phenomenological features. Psychiatry Research, 292, 1-9. [113314]. https://doi.org/10.1016/j.psychres.2020.113314
Badcock, J. C., Laroi, F., Kamp, K., Kelsall-Foreman, I., Bucks, R. S., Weinborn, M., Begemann, M., Taylor, J-P., Collerton, D., O'Brien, J. T., El Haj, M., Ffytche, D., & Sommer, I. E. (2020). Hallucinations in Older Adults: A Practical Review. Schizophrenia Bulletin, 46(6), 1382-1395. https://doi.org/10.1093/schbul/sbaa073
Sommer, I. E. C. (2020). Het vrouwenbrein. Uitgeverij Atlas Contact.
Faay, M. D. M., van Baal, G. C. M., Arango, C., Diaz-Caneja, C. M., Berger, G., Leucht, S., Bobes, J., Saiz, P. A., Paz Garcia-Portilla, M., van de Brug, R., Petter, J., Winter-van Rossum, I., & Sommer, I. E. (2020). Hostility and aggressive behaviour in first episode psychosis: Results from the OPTiMiSE trial. Schizophrenia Research, 223, 271-278. https://doi.org/10.1016/j.schres.2020.08.021
Liu, X., Eickhoff, S. B., Hoffstaedter, F., Genon, S., Caspers, S., Reetz, K., Dogan, I., Eickhoff, C. R., Chen, J., Caspers, J., Reuter, N., Mathys, C., Aleman, A., Jardri, R., Riedl, V., Sommer, I. E., & Patil, K. R. (2020). Joint Multi-modal Parcellation of the Human Striatum: Functions and Clinical Relevance. Neuroscience bulletin, 36(10), 1123-1136. https://doi.org/10.1007/s12264-020-00543-1
de Boer, J. N., Voppel, A. E., Brederoo, S. G., Wijnen, F. N. K., & Sommer, I. E. C. (2020). Language disturbances in schizophrenia: the relation with antipsychotic medication. NPJ Schizophrenia, 6(1), [24]. https://doi.org/10.1038/s41537-020-00114-3
de Boer, J. N., van Hoogdalem, M., Mandl, R. C. W., Brummelman, J., Voppel, A. E., Begemann, M. J. H., van Dellen, E., Wijnen, F. N. K., & Sommer, I. E. C. (2020). Language in schizophrenia: relation with diagnosis, symptomatology and white matter tracts. NPJ Schizophrenia, 6(1), [10]. https://doi.org/10.1038/s41537-020-0099-3
Di Biase, M. A., Zhang, F., Lyall, A., Kubicki, M., Mandl, R. C. W., Sommer, I. E., & Pasternak, O. (2020). Neuroimaging auditory verbal hallucinations in schizophrenia patient and healthy populations. Psychological Medicine, 50(3), 403-412. https://doi.org/10.1017/S0033291719000205

2019

Dauwan, M., Begemann, M. J. H., Slot, M. I. E., Lee, E. H. M., Scheltens, P., & Sommer, I. E. C. (2021). Physical exercise improves quality of life, depressive symptoms, and cognition across chronic brain disorders: a transdiagnostic systematic review and meta-analysis of randomized controlled trials. Journal of Neurology, 268(4), 1222-1246. https://doi.org/10.1007/s00415-019-09493-9
van der Horn, H. J., Out, M. L., de Koning, M. E., Mayer, A. R., Spikman, J. M., Sommer, I. E., & van der Naalt, J. (2020). An integrated perspective linking physiological and psychological consequences of mild traumatic brain injury. Journal of Neurology, 267(9), 2497-2506. https://doi.org/10.1007/s00415-019-09335-8
Pharmacotherapy Monitoring, Chen, J., Patil, K. R., Weis, S., Sim, K., Nickl-Jockschat, T., Zhou, J., Aleman, A., Sommer, I. E., Liemburg, E. J., Hoffstaedter, F., Habel, U., Derntl, B., Liu, X., Fischer, J. M., Kogler, L., Regenbogen, C., Diwadkar, V. A., Stanley, J. A., ... Jorg, F. (2020). Neurobiological Divergence of the Positive and Negative Schizophrenia Subtypes Identified on a New Factor Structure of Psychopathology Using Non-negative Factorization: An International Machine Learning Study. Biological Psychiatry, 87(3), 282-293. https://doi.org/10.1016/j.biopsych.2019.08.031
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