Alcohol Use Disorders and Risk of Parkinson's Disease

In This Article

Background

Little is known about the aetiology of Parkinson's disease (PD), which is the second most common neurodegenerative disorder following Alzheimer's disease. It is believed that major gene mutations cause only a small proportion of the cases and that environmental factors are involved. Occupational exposures such as pesticides and herbicides seem to increase the risk for PD, and possibly lead to damage of dopaminergic cells.^[1,2]

Alcohol has been suggested to protect from neurodegeneration and vascular disease although the mechanisms are not clear.^[3] For instance flavonoids that can be found in red wine, might have neuro^[4] and vascular protective effects.^[5] One review from 2005 came to the conclusion that there was some evidence for a decreased risk of PD associated with alcohol consumption, although most studies did not reach statistical significance.^[3] Another review from 2011 states the epidemiological evidence on these associations to be limited.^[6] Even though there is no association between lower consumption of alcohol and PD, or a modest protective effect, it is still possible that chronic heavy consumption of alcohol could have dopamine neurotoxic effects relevant for PD, as shown in an experimental animal study by Gilman et al..^[7]

Most previous studies on alcohol consumption and the risk of PD have used cross-sectional designs, including self-report of low to moderate alcohol consumption. At this time, most studies have not addressed adequately the risk of PD among individuals with heavy alcohol use or those who would qualify for alcohol abuse or dependence diagnoses. Also, studies investigating the prospective association between alcohol use disorders and PD which takes into account the long latency period for developing PD have not been performed. To our knowledge, only one study has investigated the association between diagnosed alcohol use disorders and PD.^[8] This study used the General Practice Research Database in the United Kingdom and found no association, although had a limited follow-up period.

The aim of this study was to investigate the influence of alcohol use disorders on the risk for developing PD in a national-wide study with a long follow-up period. We prospectively studied in a cohort from the Swedish National Inpatient Register, the association between a diagnosis of an alcohol use disorder and a diagnosis of PD up to 37 years later and compared with a population-proxy group.

Table 1. Number of individuals with a diagnosis of an alcohol use disorder or appendicitis (n = 602,930) in the Swedish National Inpatient Register 1972–2008, distributed by age and sex
	Alcohol use disorders (n = 276,527)		Parkinson's disease among individuals with alcohol use disorders (n = 1,083)		Appendicitis (n = 326,403)		Parkinson's disease among individuals with appendicitis (n = 658)
	Women (%)	Men (%)	Women (%)	Men (%)	Women (%)	Men (%)	Women (%)	Men (%)
Total	73,794 (100)	202,733 (100)	208 (100)	875 (100)	149,233 (100)	177,178 (100)	271 (100)	387 (100)
Age
≤29	24,691 (33.5)	43,737 (21.6)	0	0	89,676 (60.1)	106,762 (60.3)	2 (0.7)	3 (0.8)
30 - 44	20,542 (27.8)	61,904 (30.5)	4 (1.9)	10 (1.1)	26,653 (17.9)	36,070 (20.4)	2 (0.7)	3 (0.8)
45 - 59	18,539 (25.1)	60,109 (29.7)	28 (13.5)	91 (10.4)	16,996 (11.4)	18,952 (10.7)	16 (5.9)	37 (9.6)
60 - 74	7,989 (10.8)	31,377 (15.5)	103 (49.5)	456 (52.1)	11,081 (7.4)	11,527 (6.5)	93 (34.3)	133 (34.4)
≥75	2,033 (2.8)	5,606 (2.8)	73 (35.1)	318 (36.3)	4,827 (3.3)	3,859 (2.2)	158 (58.3)	211 (54.5)

Table 2. HRs and 95% CIs for the association between alcohol use disorders and Parkinson's disease in the Swedish National Inpatient Register 1972–2008, n = 602,930
		Total population	Parkinson's disease
		n	n	HR^a	(95% CI)	p-value ^b
Appendicitis	Reference	326,403	658	1
Alcohol	Model 1^c	276,527	1,086	2.57	(2.32–2.82)	<.0001
	Model 2			1.52	(1.38–1.67)	<.0001
	Model 3			2.42	(2.19–2.67)	<.0001
	Model 4			1.38	(1.25–1.53)	<.0001

^aAbbreviations: HRs, hazard ratios.
^bTested with 95% significant level.
^cModel 1 crude. Model 2 adjusted for age at exposure.
Model 3 adjusted for sex.
Model 4 adjusted for age at exposure and se

Table 3. HRs and 95% CIs for the association between alcohol use disorders and Parkinson's disease in women and men in the Swedish National Inpatient Register 1972–2008, n = 602,930
		Women					Men
		Total	Parkinson's disease				Total	Parkinson's disease
		n	n	HR^a	(95% CI)	p-value ^b	n	n	HR^a	(95% CI)	p-value ^b
Appendicitis	Reference	149,233	271	1			177,170	387	1
Alcohol	Model 1^c	73,794	208	2.31	(1.92–2.77)	<.0001	202,733	878	2.48	(2.20–2.79)	<.0001
	Model 2			1.64	(1.37–1.97)	<.0001			1.28	(1.14–1.44)	<.0001

^aAbbreviations: HRs, hazard ratios.
^bTested with 95% significant level.
^cModel 1 crude.
Model 2 adjusted for age at exposure.

Table 4. HRs and 95% CIs for the association between alcohol use disorders and Parkinson's disease distributed by age of first admission with Parkinson's disease in the Swedish National Inpatient Register 1972–2008, n = 602,930
	Total population	≤44				45–59				60–74				≥75
	n	n	HR^a	(95% CI)	p-value^b	n	HR^a	(95% CI)	p-value^b	n	HR^a	(95% CI)	p-value^b	n	HR^a	(95% CI)	p-value^b
Appendicitis ref	326,403	10	1			53	1			226	1			369	1
Alcohol model 1^c	276,527	14	2.71	(1.20–6.10)	0.016	119	3.58	(2.59–4.94)	0.0001	559	3.78	(3.24–4.41)	<.0001	391	1.67	(1.45–1.93)	<.0001
Model 2			2.41	(0.98–5.90)	0.056		1.94	(1.38–2.72)	<.0001		2.00	(1.71–2.34)	<.0001		1.03	(0.89–1.18)	0.732
Model 3			2.69	(1.17–6.12)	0.020		3.37	(2.42–4.69)	<.0001		3.55	(3.03–4.16)	<.0001		1.60	(1.38–1.85)	<.0001
Model 4			2.39	(0.96–5.93)	0.060		1.84	(1.30–2.60)	0.0006		1.84	(1.58–2.18)	<.0001		0.91	(0.78–1.06)	0.226

^aAbbreviations: HRs, hazard ratios.
^bTested with 95% significant level.
^cModel 1 crude. Model 2 adjusted for age at exposure.
Model 3 adjusted for sex.
Model 4 adjusted for age at exposure and sex.