To identify methodological categories, the
outcome of each paper was classified
according to a set of binary
variables: 1 -
outcome measured on biological material; 2 -
outcome measured on human material; 3 -
outcome exclusively behavioural (measures of behaviours and interactions between individuals, which in studies on people included surveys, interviews and social and economic data); 4 -
outcome exclusively non-behavioural (physical, chemical and other measurable parameters including weight, height, death, presence / absence, number of individuals, etc...).
Dichotomized measures: For the second hypothesis, continuous fish and processed food
variables were dichotomized (
according to dietary recommendations) to investigate interactions between food intake and CP trajectories, and associations with co-occurring difficulty
outcomes.