“…Given the assumption that the rate of change holds relatively constant as treatment progresses beyond 6 months, somewhere between 12 and 18 months of treatment would be necessary for attaining large effects on average in four of the five outcome domains examined (Paper IV). This would be in line with previous studies on the development of social functioning in patients with APD (Kvarstein et al, 2021) and improvements in more complex characterological phenomena that involve changes in structural capacities (Bateman & Fonagy, 2009;Dimaggio et al, 2017;Giesen-Bloo et al, 2006;Gordon-King et al, 2018;Linehan, 1993;Monsen et al, 1989;K. Monsen & Monsen, 2000;Nordmo et al, 2020;Normann-Eide et al, 2015;Solbakken et al, 2012), indicating a need for long-term treatment to detect more comprehensive changes.…”