DANLIFE: The DANish LIFE course cohort

The DANish LIFE course cohort (DANLIFE) is a nationwide, register-based, life-course cohort that is based on comprehensive and continuously updated information on social adversity and major life events from the Danish registers. These unique data from a large, unselected population provide an unprecedented resource for testing life-course mechanisms, such as sensitive periods and the accumulation of various stress factors across childhood, adolescence and young adulthood.

The DANLIFE cohort is comprised of all people born in Denmark from 1980 onwards, so far totaling more than two million people who have been followed from birth until middle adulthood.

Data

The DANLIFE cohort includes linked data from the Danish registers. Every person born in Denmark is assigned a unique 10-digit personal identification (CPR, det centrale personregister) number at birth, which provides a direct link between information from both administrative and research registers in Denmark. This anonymous civil-registration   number also gives researchers an exceptional opportunity to follow individuals longitudinally over time.

Prevalence of childhood adversity

The DANLIFE cohort includes all children born in Denmark since 1980, which so far totals more than two million people. Using the nationwide Danish registers, we have measured a wide range of stressful childhood adversities in DANLIFE (see the specific adversities and their definitions here). Parental separation (29%), parental long-term unemployment (25%), and parental somatic illness (12%), are so far the most frequently experienced adversities before 18 years of age, while parental drug abuse (2%), sibling psychiatric illness (1%), and sibling death (1%) have been the least common adversities. However, in the large population sample of DANLIFE, even these small proportions correspond to several thousand individuals (e.g., 10,543 individuals younger than 18 had experienced the death of a sibling).

Social gradient in the accumulation of childhood adversities

Almost half (47%) of the study population did not experience any adversities before age 18, while one in 10 people experienced three or more of the 12 specific adversities at least once before their 18th birthday. We identified a strong social gradient in the accumulation of childhood adversities: e.g., 20% of the children who were born to mothers with a low level of education (≤9 years of education) had been exposed to three or more adversities before age 18 whereas only 4% of the children born to mothers with a high level of education (>12 years of education) had experienced similar exposures. The mean number of adversities experienced was 1.5 amongst persons whose mothers had low levels of education and 0.5 amongst children whose mothers had high levels of education.

DANLIFE cohort profile

Read the DANLIFE cohort profile published in BMJ Open: Cohort profile: the DANish LIFE course (DANLIFE) cohort, a prospective register-based cohort of all children born in Denmark since 1980