Neurology: Genes predict smoking, alcohol consumption, and functional outcomes after ischemic stroke

In traditional epidemiological studies, smoking and alcohol consumption are inversely associated with
prognosis after stroke.
Recently, a study published in Neurology used the Mendelian randomization (MR) framework to explore the genetically predicted relationship
between smoking and alcohol consumption and post-stroke prognosis.

Genome-wide Association Study (GWAS) data from individuals of European ancestry were selected for initiation of smoking and
drinking.
Pooled level data on functional outcomes after ischaemic stroke were derived from genetic networks of functional outcomes in ischaemic stroke in patients of European ancestry
.
Univariate and multivariate inverse variance weighted MR methods were used for causal estimation
.
Sensitivity analysis was performed using weighted median, MR robustness-adjusted profile score, and MR-Egger regression methods
.
The Q and I2 statistics were used to assess heterogeneity
in MR estimates between variants.

Univariate IVW MR analysis showed that the genetic predisposition to start smoking was associated with poor functional prognosis after ischemic stroke (OR=1.
48; 95% CI: 1.
0 8~2.
0 1, P=0.
013).

In multivariate MR analyses, this association remained significant after adjusting for genetically predicted alcohol consumption (OR=1.
5 6; 95% CI: 1.
0 5-2.
32, P=0.
027).

Genetically predicted alcohol consumption was not associated with functional outcomes after ischaemic stroke (P>0.
05
).
Sensitivity analyses performed with other methods, as well as analyses in models that did not adjust for baseline stroke severity, yielded similar results and found no evidence of heterogeneity in MR estimates between variables (P>0.
05).

The findings provide genetic support for the causal relationship between smoking and poor functional outcomes after ischaemic stroke, and have important implications
for recovery after stroke.
Smoking cessation and avoidance
should be promoted in patients with ischaemic stroke.

Sources: Zhang Z, Wang M, Gill D, Liu X.
Genetically Predicted Smoking and Alcohol Consumption and Functional Outcome After Ischemic Stroke [published online ahead of print, 2022 Sep 21].
Neurology.
2022; 10.
1212/WNL.
0000000000201291.
doi:10.
1212/WNL.
0000000000201291