Is the Association Between Alcohol Consumption and Mental Well-Being in University Students Linear, Curvilinear or Absent?

Figures & data

Table 1. Descriptive information and independent sample t-test output of gender differences in alcohol consumption and the six indicators of mental well-being.

		Total (N = 3629)	Females (n = 2631)	Males (n = 998)	Independent sample t-tests
	Range	M (SD)	M (SD)	M (SD)	t	p	d
Alcohol	0–12	3.45 (2.33)	3.36 (2.26)	3.70 (2.47)	−4.03	<.001*	.15
Depression	8–32	16.42 (4.43)	16.68 (4.45)	15.75 (4.31)	5.67	<.001*	−0.21
Anxiety	0–6	2.26 (1.71)	2.43 (1.71)	1.80 (1.60)	10.01	<.001*	−0.37
Stress	0–40	16.83 (6.84)	17.60 (6.71)	14.81 (6.76)	11.41	<.001*	−0.41
Life satisfaction	1–4	3.03 (.62)	3.02 (.60)	3.08 (.66)	−2.62	.008*	.10
Happiness	1–10	6.88 (1.43)	6.85 (1.40)	6.97 (1.49)	−2.91	.004*	.09
Mental health	1–5	2.77 (1.07)	2.67 (1.01)	3.03 (1.16)	−9.33	<.001*	.35

n, participants per group; M, mean; SD, standard deviation; t, t-value; p, p-value; d, Cohen’s d. Degrees of freedom were 3627 for all independent sample t-tests.

Table 2. Mean scores of the mental well-being variables for abstainers, moderate drinkers, and excessive drinkers, separately for females and males.

Females	Abstainer (1)	Moderate (2)	Excessive (3)	One-way ANOVA^a
	M (SD)	M (SD)	M (SD)	F	p	Post-hoc
Females N (%)	332 (12.6%)	2190 (83.2%)	109 (4.1%)
Depression	17.56 (4.55)	16.51 (4.42)	17.27 (4.58)	8.98	<.001*	1 > 2
Anxiety	2.70 (1.78)	2.39 (1.70)	2.41 (1.79)	4.88	.008*	1 > 2
Stress	18.65 (7.06)	17.36 (6.61)	19.21 (7.22)	8.73	<.001*	1, 3 > 2
Life satisfaction	2.88 (.65)	3.04 (.59)	3.05 (.66)	10.10	<.001*	1 < 2
Happiness	6.46 (1.51)	6.90 (1.37)	6.86 (1.54)	14.54	<.001*	1 < 2, 3
Mental Health	2.49 (1.02)	2.69 (1.01)	2.66 (1.02)	5.68	.003*	1 < 2, 3
Males	M (SD)	M (SD)	M (SD)	F	p	Post-hoc
Males N (%)	140 (14.0%)	827 (82.9%)	31 (3.1%)
Depression	15.51 (3.92)	15.78 (4.37)	15.94 (4.23)	.26	.774	NA
Anxiety	1.75 (1.52)	1.82 (1.62)	1.71 (1.51)	.16	.851	NA
Stress	14.72 (6.97)	14.82 (6.78)	15.06 (4.92)	.04	.945	NA
Life satisfaction	3.06 (0.59)	3.08 (0.67)	3.10 (0.70)	.09	.091	NA
Happiness	6.94 (1.34)	6.98 (1.52)	7.00 (1.51)	.06	.945	NA
Mental Health	2.91 (1.22)	3.05 (1.16)	3.03 (1.02)	.96	.960	NA

n, participants per group; M, mean; SD, standard deviation; F, F-value; p, p-value; NA, not applicable.

^a Differences in mean between groups were tested with a one-way ANOVA. The post-hoc column indicates which groups significantly differ from each other. Effect sizes (Eta Squared; η²) were low for females based on the criteria of Cohen et al., (2003); depression, η² = 0.003; anxiety, η² = 0.001; life satisfaction, η² = 0.004; happiness, η² = 0.006; happiness, η² = 0.003).

Figure 1. AUDIT-c and depression. The GAM model was adopted. ggPlot visualizations of the significant LM and GAM in the relationship between AUDIT-c score and depression for females. The dotted line indicates the LM, full line indicates the GAM. The size of the dots refers to the number of observations per data point.

Figure 2. AUDIT-c and anxiety. LM model was adopted. ggPlot visualizations of the significant LM and GAM in the relationship between AUDIT-c score and anxiety for females. The dotted line indicates the LM, full line indicates the GAM. The size of the dots refers to the number of observations per data point.

Figure 3. AUDIT-c and perceived stress. The GAM model was adopted. ggPlot visualizations of the significant GAM in the relationship between AUDIT-c score and perceived stress for females. The full line indicates the GAM. The size of the dots refers to the number of observations per data point.

Figure 4. AUDIT-c and life satisfaction. LM model was adopted. ggPlot visualizations of the significant LM and GAM in the relationship between AUDIT-c score and life satisfactionfor females. The dotted line indicates the LM, full line indicates the GAM. The size of the dots refers to the number of observations per data point.

Figure 5. AUDIT-c and happiness. The GAM model was adopted. ggPlot visualizations of the significant LM and GAM in the relationship between AUDIT-c score and happiness for females. The dotted line indicates the LM, full line indicates the GAM. The size of the dots refers to the number of observations per data point.

Figure 6. AUDIT-c and mental health. LM model was adopted. ggPlot visualizations of the significant LM and GAM in the relationship between AUDIT-c score and self-rated mental health score for females. The dotted line indicates the LM, full line indicates the GAM. The size of the dots refers to the number of observations per data point.

Table 3. Results of the linear and curvilinear models for the relationship between alcohol consumption (AUDIT-c) and each of the indicators of mental well-being for females and males separately.

	Linear model						Curvilinear model				Comparison
Females	B	Beta	%R^2	T	p	AIC	%R^2	F	p	AIC	Chi-square	AIC diff
Depression	−0.13	−0.07	.4%	−3.52	<.001*	15318.38	.9%	6.81	<.001*	15308.54	.002*	Δ = 9.84
Anxiety	−0.06	−0.07	.5%	−3.65	<.001*	10289.65	.5%	6.93	<.001*	10288.58	.140	Δ = 1.07
Stress	−0.11	−0.03	.1%	−1.90	.058	17487.87	.8%	5.92	<.001*	17471.12	NA	Δ = 16.75
Life satisfaction	.03	.1	1%	5.42	<.001*	4774.686	1%	12.57	<.001*	4770.676	.032	Δ = 4.01
Happiness	.05	.07	.5%	3.66	<.001*	9227.753	1%	4.27	<.001*	9216.483	<.001*	Δ = 11.27
Mental health	.04	.09	.8%	4.85	<.001*	7501.511	1%	10.71	<.001*	7499.456	.084	Δ = 2.06
Males	B	Beta	%R^2	T	P	AIC	%R^2	F	p	AIC	p	AIC diff
Depression	−0.03	−0.02	−0.06%	−0.61	.541	5750.943	−0.06%	.373	.541	5750.943	NA	Δ ≈ 0
Anxiety	−0.004	−0.03	−0.1%	−0.20	.843	3780.195	−0.1%	.039	.843	3780.195	NA	Δ ≈ 0
Stress	−0.04	−0.03	−0.08%	−0.43	.666	6647.819	−0.08%	.186	.666	6647.819	NA	Δ ≈ 0
Life satisfaction	.01	.05	.2%	1.76	.079	1999.228	.2%	3.097	.079	1999.228	NA	Δ ≈ 0
Happiness	.02	.01	.02%	1.10	.272	3635.931	.02%	1.21	.272	3635.931	NA	Δ ≈ 0
Mental health	.03	.06	.3%	2.10	.036	3133.752	.3%	4.41	.036	3133.752	NA	Δ ≈ 0

If both linear and curvilinear models were significant, the model comparison shows whether the GAM model fitted significantly better than the LM model. The Benjamini-Hochberg procedure reduced the critical p-value of p = 0.023 (significance is indicated by *) The best fitting model (according to the Chi-square) is indicated in bold. B, regression slope; Beta, correlation coefficient; %R², percentage explained variance by the model; T, t-statistic; p, p-value; AIC, AIC value; AIC diff, model with highest AIC value minus model with lowest AIC value. Based on the rules of thumb by Burnham & Anderson (2004, p. 271), conclusions based on the AIC diff values confirm the Chi-square conclusions. Rules of thumb: Δ < 2, substantial support for a model with the highest AIC value (e.g., LM and GAM similar fit); 4 < Δ > 7, low support for a model with the highest AIC value (e.g., LM probably fits worse); Δ > 10, no support for a model with highest AIC value (e.g., LM model fits worse).

Data availability

The dataset in this manuscript is part of a larger project (the Healthy Student Life project, https://www.ru.nl/bsi/research/group-pages/healthy-student-life/.). The dataset and scripts generated and analyzed for the current study are available from the corresponding author upon reasonable request.