Episodes
of shorter duration (between 1 and 3 days) during which young people experience manic symptoms are certainly much more common
than classical (hypo --RRB- mania in
general population samples.3 In addition, evidence from longitudinal clinical studies suggests that up to 40 %
of people who experience such
shorter episodes (often termed BD - not otherwise specified, BD - NOS) may go on to develop classical (4 — 7 days) BD.9 However, more evidence is required to decide whether these
short - lived episodes
of mania - like symptoms are aetiologically linked with BD.