Identity Formation in Adolescence: Change or Stability?

The aim of this five-wave longitudinal study of 923 early to middle adolescents (50.7% boys; 49.3% girls) and 390 middle to late adolescents (43.3% boys and 56.7% girls) is to provide a comprehensive view on change and stability in identity formation from ages 12 to 20. Several types of change and stability (i.e., mean-level change, rank-order stability, and profile similarity) were assessed for three dimensions of identity formation (i.e., commitment, in-depth exploration, and reconsideration), using adolescent self-report questionnaires. Results revealed changes in identity dimensions towards maturity, indicated by a decreasing tendency for reconsideration, increasingly more in-depth exploration, and increasingly more stable identity dimension profiles. Mean levels of commitment remained stable, and rank-order stability of commitment, in-depth exploration, and reconsideration did not change with age. Overall, girls were more mature with regard to identity formation in early adolescence, but boys had caught up with them by late adolescence. Taken together, our findings indicate that adolescent identity formation is guided by progressive changes in the way adolescents deal with commitments, rather than by changes in the commitments themselves

Daily identity dynamics in adolescence shaping identity in emerging adulthood: An 11-year longitudinal study on continuity in development

According to identity theory, short-term day-to-day identity exploration and commitment processes are the building blocks for long-term development of stable commitments in emerging adulthood. This key assumption was tested in a longitudinal study including 494 individuals (43% girls, M age T1 = 13.31 years, range 11.01–14.86 years) who were followed from adolescence into emerging adulthood, covering ages 13 to 24 years. In the first five years, adolescents reported on their daily identity processes (i.e., commitment, reconsideration and in-depth exploration) across 75 assessment days. Subsequently, they reported on their identity across four (bi-) annual waves in emerging adulthood. Findings confirmed the existence of a dual-cycle process model of identity formation and identity maintenance that operated at the within-person level across days during adolescence. Moreover, individual differences in these short-term identity processes in adolescence predicted individual differences in identity development in emerging adulthood. Specifically, those adolescents with low daily commitment levels, and high levels of identity reconsideration were more likely to maintain weak identity commitments and high identity uncertainty in emerging adulthood. Also, those adolescents characterized by stronger daily changes in identity commitments and continuing day-to-day identity uncertainty maintained the highest identity uncertainty in emerging adulthood. These results support the view of continuity in identity development from short-term daily identity dynamics in adolescence to long-term identity development in emerging adulthood

Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium.

Cannabis is the most widely produced and consumed illicit psychoactive substance worldwide. Occasional cannabis use can progress to frequent use, abuse and dependence with all known adverse physical, psychological and social consequences. Individual differences in cannabis initiation are heritable (40-48%). The International Cannabis Consortium was established with the aim to identify genetic risk variants of cannabis use. We conducted a meta-analysis of genome-wide association data of 13 cohorts (N=32 330) and four replication samples (N=5627). In addition, we performed a gene-based test of association, estimated single-nucleotide polymorphism (SNP)-based heritability and explored the genetic correlation between lifetime cannabis use and cigarette use using LD score regression. No individual SNPs reached genome-wide significance. Nonetheless, gene-based tests identified four genes significantly associated with lifetime cannabis use: NCAM1, CADM2, SCOC and KCNT2. Previous studies reported associations of NCAM1 with cigarette smoking and other substance use, and those of CADM2 with body mass index, processing speed and autism disorders, which are phenotypes previously reported to be associated with cannabis use. Furthermore, we showed that, combined across the genome, all common SNPs explained 13-20% (P<0.001) of the liability of lifetime cannabis use. Finally, there was a strong genetic correlation (rg=0.83; P=1.85 × 10(-8)) between lifetime cannabis use and lifetime cigarette smoking implying that the SNP effect sizes of the two traits are highly correlated. This is the largest meta-analysis of cannabis GWA studies to date, revealing important new insights into the genetic pathways of lifetime cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use