London, Aug 14 (IANS) Incidence of subarachnoid haemorrhage (SAH) , the most fatal type of stroke has declied in Finland as a result of national tobacco policies that led to a significant reduction in smoking levels, says a study.
Over a period of 15 years (1998-2012) the study examined the changes in the incidence of SAH, and these contrasted with changes in the prevalence of smoking -- a key risk factor for SAH.
SAH is typically caused by a ruptured cerebral aneurysm and leads to a sudden increase in the intracranial pressure.
The results indicated that the number of people afflicted with SAH was nearly half of the previously assumed figure and also the number is in rapid decline, a trend which was particularly apparent in younger generations.
Within 15 years, the prevalence of SAH among women and men under 50-years of age has decreased by 45 per cent and 38 per cent respectively.
During the same period, the prevalence of disease decreased by 16 per cent among women, and 26 per cent among men, over 50-years of age.
Smoking among Finns aged between 15 to 64 years of age has been decreased by 30 per cent during the monitoring period.
"It is extraordinary for the incidence of any cardiovascular disease to decrease so rapidly at the population level in such a short time," said Jaakko Kaprio, Professor at the University of Helsinki.
Previously it was believed that in Finland nearly a thousand people suffer SAH every year - most of them were adults of working age, and half of them who got afflicted died within a year, the study said, in the paper published in the journal Neurology.
"Even though we cannot demonstrate a direct causation in nation-wide studies, it is highly likely that the national tobacco policies in Finland have contributed to the decline in the incidence of this type of severe brain haemorrhage," Kaprio added.
Cerebral aneurysms, which are fairly common, are present in up to more than 10 per cent of people over the age of 70 but most of them never rupture.
"Previous studies have indicated that smoking is one of the most important susceptibility factors for rupturing aneurysms, so in that sense the now established connection between a decrease in smoking and a decrease in SAH is not surprising," added Miikka Korja, Neurosurgeon at Helsinki University Hospital.
