Association between smoking and cognitive impairment in multiple sclerosis

Figures & data

Table 1 Demographics and clinical characteristics

	Nonsmokers (n=24)	Heavy smokers (n=20)	t, z, or χ^2	P-value
Age, years	34.92±12.5	40.10±7.25	t=1.715	0.095
Sex, male:female	9:15	13:7	χ^2=3.30	0.069
Education duration, years	8.83±3.65	8.50±3.77	z=0.273	0.785
Duration of MS diagnosis, years	5.88±6.35	6.40±5.88	z=0.42	0.675
EDSS score, average (range)	1.75 (1.0–7.0)	1.5 (1.0–6.5)	z=0.17	0.865
Beck Depression Inventory score	16.04±13.70	17.05±11.57	z=0.65	0.516
MS types			χ^2=1.38	0.5
– Relapsing-remitting, n	18	16
– Secondary progressive, n	5	2
– Primary progressive, n	1	2

Note: Data are expressed as the mean ± standard deviation unless otherwise specified.

Abbreviations: MS, multiple sclerosis; EDSS, Expanded Disability Status Scale.

Table 2 Cognitive score comparisons between heavy smokers and nonsmokers

	Nonsmokers (n=24)	Heavy smoker (n=20)	t, z, or χ^2	P-value
PASAT	40.04±35.27	33.40±32.80	z=0.562	0.574
SRT	45.17±10.32	45.25±8.38	t=0.029	0.977
SRT-DR	7.33±2.58	6.60±3.36	t=0.818	0.418
SPART	16.13±5.15	14.50±6.71	t=0.909	0.369
SPART-DR	5.25±1.75	4.75±2.34	t=0.811	0.422
SDMT	31.58±15.87	28.95±10.54	z=0.602	0.547
WLG	17.92±3.74	19.05±5.39	t=0.820	0.417
Cognitive impairment (%)	29.2	60.0	χ^2=4.227	0.04

Notes: Data are expressed as the mean ± standard deviation unless otherwise specified. Patients scoring in the fifth percentile or less in at least two of these tests were considered to have cognitive impairment according to the normative data from the general Turkish population. Bold indicates a statistically significant P-value.

Abbreviations: PASAT, Paced Auditory Serial Addition Test; SRT, Selective Reminding Test; SRT-DR, SRT-delayed recall; SPART, Spatial Recall Test; SPART-DR, SPART-delayed recall; SDMT, Symbol Digit Modalities Test; WLG, word list generation.

Table 3 Results of the logistic regression model for predictors of cognitive impairment

	β (SE)	P-value	95% CI for odds ratio
			Lower	Odds ratio	Upper
Constant	−1.48 (0.62)
EDSS	0.47 (0.19)	0.016	1.091	1.594	2.328
Smoking status (heavy smoking)	0.84 (0.37)	0.023	1.124	2.327	4.816

Notes: R²=0.19 (Hosmer–Lemeshow test), 0.23 (Cox and Snell), 0.30 (Nagelkerke). Model χ²(2)=11.265, P=0.004.

Abbreviations: CI, confidence interval; EDSS, Expanded Disability Status Scale; SE, standard error.