Background Recent data have suggested that stroke incidence in young people may be rising. In this population-based study, we aimed to determine whether the incidence of stroke in people aged <55 years old had changed over the last three decades.

Methods All cases of first-ever stroke (ischaemic stroke, spontaneous intracerebral haemorrhage, and undetermined stroke) occurring in Dijon, France, from 1985 to 2011 were prospectively collected from a population-based registry. Incidence rates were calculated and temporal trends were analysed by age groups and stroke subtypes using a Poisson regression to estimate incidence rate ratios (IRR). Risk factors and premorbid treatments were analysed.

Results Over the 27-year study period, 4506 patients were recorded (53% women, mean age 74.6±14.4, 10.1% aged <55 years). An increase in overall stroke incidence was noted, as was a rise in ischaemic stroke in individuals aged <55 years (IRR 1.308; 95% CI 0.982 to 1.741, p=0.066 for period 1994–2002 vs period 1985–1993, and IRR 1.697; 95% CI 1.340 to 2.150, p<0.001 for period 2003–2011 vs period 1994–2002), which was consistent for men and women. In these young patients, smoking was the most frequent risk factor (43%).

Conclusions Multiple factors may account for the increased incidence of ischaemic stroke in people aged <55 years including changes in vascular risk factors, better awareness of the disease and treatment options in the population and among practitioners leading to more frequent referrals for specialised care, and improvements in stroke diagnosis. Stroke prevention must be encouraged even in young adults.