Genetic, lifestyle factors tied to risk of stroke
Genetic and lifestyle factors appear to independently impact the risk of incident stroke, highlighting the potential of a healthy lifestyle in reducing the risk across entire populations, even in those at high genetic risk of stroke, according to a recent study.
“A high genetic risk combined with an unfavourable lifestyle profile was associated with a more than twofold increased risk of stroke compared with a low genetic risk and a favourable lifestyle,” researchers said.
A total of 2,077 incident strokes (1,541 ischaemic stroke, 287 intracerebral haemorrhage and 249 subarachnoid haemorrhage) were recorded during a median follow-up of 7.1 years.
Participants at high genetic risk (top third of polygenic score) had 35-percent higher risk of incident stroke than those at low genetic risk (bottom third; hazard ratio [HR], 1.35; 95 percent CI, 1.21–1.50; p=3.9×10−8). [BMJ 2018;363:k4168]
Moreover, participants with unfavourable lifestyle (0 or 1 healthy lifestyle factor) were more likely to have a 66-percent increased risk of stroke compared with those with a favourable lifestyle (3 or 4 lifestyle factors; HR, 1.66; 1.45–1.89; p=1.19×10−13). The association with lifestyle was independent of genetic risk strata.
“The present study provides further support that common genetic variants are implicated in the development of stroke,” researchers said. “Our findings showing that a polygenic risk score is associated with incident stroke is in line with both clinical and population-based studies.” [Eur J Hum Genet 2015;23:969-974; Stroke 2014;45:403-412; Stroke 2014;45:2856-2862; Stroke 2016;47:1174-1179]
On the other hand, several studies have reported the reduction of stroke risk by adhering to a healthy lifestyle. [Circulation 2008;118:947-954; Neurology 2015;84:2224-2228; Arch Intern Med 2011;171:1811-1818; BMJ 2009;338:b349; Neurology 2014;83:1699-1704]
“The risk reduction associated with adherence to a healthy lifestyle in the present study was similar across all stratums of genetic risk, which emphasizes the benefit for entire populations of adhering to a healthy lifestyle, independent of genetic risk,” researchers said.
The most statistically significant associations among the lifestyle factors were for smoking and body mass index (BMI) ≥30 kg/m2.
In the present prospective population-based cohort study, 306,473 men and women (aged 40–73 years) were recruited between 2006 and 2010. Cox regression was used to estimate HRs for a first stroke.
Researchers constructed a polygenic risk score of 90 single nucleotide polymorphisms previously associated with stroke at p<1×10−5 to test for an association with incident stroke. Adherence to a healthy lifestyle was determined based on the following factors: nonsmoker, healthy diet, BMI <30 kg/m2 and regular physical exercise.
Further studies are warranted to examine the effect of the duration of exposure to an unfavourable lifestyle profile on the risk of stroke, as well as to test such associations in more diverse populations, according to researchers.