The British journal of psychiatry 219(6), 659-669 (2021). doi:10.1192/bjp.2021.102 British Journal of Psychiatry British Journal of Psychiatry, 2021, 219 (6), pp.659-669. ⟨10.1192/bjp.2021.102⟩ British Journal of Psychiatry, Royal College of Psychiatrists, 2021, 219 (6), pp.659-669. ⟨10.1192/bjp.2021.102⟩ British Journal of Psychiatry, 219(6), 659-669. Royal College of Psychiatrists The British Journal of Psychiatry Kalman, J L, Olde Loohuis, L M, Vreeker, A, McQuillin, A, Stahl, E A, Ruderfer, D, Grigoroiu-Serbanescu, M, Panagiotaropoulou, G, Ripke, S, Bigdeli, T B, Stein, F, Meller, T, Meinert, S, Pelin, H, Streit, F, Papiol, S, Adams, M J, Adolfsson, R, Adorjan, K, Agartz, I, Aminoff, S R, Anderson-Schmidt, H, Andreassen, O A, Ardau, R, Aubry, J M, Balaban, C, Bass, N, Baune, B T, Bellivier, F, Benabarre, A, Bengesser, S, Berrettini, W H, Boks, M P, Bromet, E J, Brosch, K, Budde, M, Byerley, W, Cervantes, P, Chillotti, C, Cichon, S, Clark, S R, Comes, A L, Corvin, A, Coryell, W, Craddock, N, Craig, D W, Croarkin, P E, Cruceanu, C, Czerski, P M, Dalkner, N, Dannlowski, U, Degenhardt, F, Del Zompo, M, DePaulo, J R, Djurovic, S, Edenberg, H J, Al Eissa, M, Elvsåshagen, T, Etain, B, Fanous, A H, Fellendorf, F, Fiorentino, A, Forstner, A J, Frye, M A, Fullerton, J M, Gade, K, Garnham, J, Gershon, E, Gill, M, Goes, F S, Gordon-Smith, K, Grof, P, Guzman-Parra, J, Hahn, T, Hasler, R, Heilbronner, M, Heilbronner, U, Jamain, S, Jimenez, E, Jones, I, Jones, L, Jonsson, L, Kahn, R S, Kelsoe, J R, Kennedy, J L, Kircher, T, Kirov, G, Kittel-Schneider, S, Klöhn-Saghatolislam, F, Knowles, J A, Kranz, T M, Lagerberg, T V, Landen, M, Lawson, W B, Leboyer, M, Li, Q S, Maj, M, Malaspina, D, Manchia, M, Mayoral, F, McElroy, S L, McInnis, M G, McIntosh, A M, Medeiros, H, Melle, I, Milanova, V, Mitchell, P B, Monteleone, P, Monteleone, A M, Nöthen, M M, Novak, T, Nurnberger, J I, O'Brien, N, O'Connell, K S, O'Donovan, C, O'Donovan, M C, Opel, N, Ortiz, A, Owen, M J, Pålsson, E, Pato, C, Pato, M T, Pawlak, J, Pfarr, J K, Pisanu, C, Potash, J B, Rapaport, M H, Reich-Erkelenz, D, Reif, A, Reininghaus, E, Repple, J, Richard-Lepouriel, H, Rietschel, M, Ringwald, K, Roberts, G, Rouleau, G, Schaupp, S, Scheftner, W A, Schmitt, S, Schofield, P R, Schubert, K O, Schulte, E C, Schweizer, B, Senner, F, Severino, G, Sharp, S, Slaney, C, Smeland, O B, Sobell, J L, Squassina, A, Stopkova, P, Strauss, J, Tortorella, A, Turecki, G, Twarowska-Hauser, J, Veldic, M, Vieta, E, Vincent, J B, Xu, W, Zai, C C, Zandi, P P, Di Florio, A, Smoller, J W, Biernacka, J M, McMahon, F J, Alda, M, Müller-Myhsok, B, Koutsouleris, N, Falkai, P, Freimer, N B, Andlauer, T F M & Schulze, T G & Ophoff, R A 2021, ' Characterisation of age and polarity at onset in bipolar disorder ', British Journal of Psychiatry . https://doi.org/10.1192/bjp.2021.102 Print: 0007-1250 Online:1472-1465 The British Journal of Psychiatry, Vol. 219, No. 6