Alcohol and Parkinson disease

Alcohol and Parkinson's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

A substantial body of research has examined the relationship between alcohol consumption and risk of Parkinson's disease (PD).

OBJECTIVE

To provide an updated systematic review and meta-analysis of observational studies examining the relationship between alcohol consumption and risk of PD.

METHODS

Eligible studies comparing PD risk in ever vs. never alcohol drinkers were sourced from six databases. Outcomes were pooled using standard meta-analysis techniques. Separate female and male estimates were generated from studies reporting sex-specific data. Additionally, cohort studies stratifying participants by quantity of alcohol intake were integrated in a dose-response analysis.

RESULTS

52 studies were included, totaling 63,707 PD patients and 9,817,924 controls. Our meta-analysis supported a statistically significant overrepresentation of never drinkers among PD subjects; odds ratio (OR) for ever drinking alcohol 0.84 (95% confidence interval (CI) 0.76 - 0.92). A subgroup analysis revealed similar effect estimates in females and males. A further synthesis of seven cohort studies suggested a negative, dose-dependent association between alcohol and risk of PD.

CONCLUSION

In the absence of a known neuroprotective pathway, there may be reason to doubt a true biological effect. The role of survivor bias, selection and recall bias, misclassification, and residual confounding requires consideration. Alternatively, observations might be attributable to reverse causation if those predestined for PD alter their alcohol habits during the preclinical phase. Major limitations of our study include high between-study heterogeneity (I2 = 93.2%) and lack of adjustment for key confounders, namely smoking status.

Alpha-Synuclein in Alcohol Use Disorder, Connections with Parkinson's Disease and Potential Therapeutic Role of 5' Untranslated Region-Directed Small Molecules

Alpha-synuclein (α-Syn) is a 140-amino acid (aa) protein encoded by the Synuclein alpha SNCA gene. It is the synaptic protein associated with Parkinson's disease (PD) and is the most highly expressed protein in the Lewy bodies associated with PD and other alpha synucleopathies, including Lewy body dementia (LBD) and multiple system atrophy (MSA). Iron deposits are present in the core of Lewy bodies, and there are reports suggesting that divalent metal ions including Cu2+ and Fe2+ enhance the aggregation of α-Syn. Differential expression of α-Syn is associated with alcohol use disorder (AUD), and specific genetic variants contribute to the risk for alcoholism, including alcohol craving. Spliced variants of α-Syn, leading to the expression of several shorter forms which are more prone to aggregation, are associated with both PD and AUD, and common transcript variants may be able to predict at-risk populations for some movement disorders or subtypes of PD, including secondary Parkinsonism. Both PD and AUD are associated with liver and brain iron dyshomeostasis. Research over the past decade has shown that α-Syn has iron import functions with an ability to oxidize the Fe3+ form of iron to Fe2+ to facilitate its entry into cells. Our prior research has identified an iron-responsive element (IRE) in the 5' untranslated region (5'UTR) of α-Syn mRNA, and we have used the α-Syn 5'UTR to screen for small molecules that modulate its expression in the H4 neuronal cell line. These screens have led us to identify several interesting small molecules capable of both decreasing and increasing α-Syn expression and that may have the potential, together with the recently described mesenchymal stem cell therapies, to normalize α-Syn expression in different regions of the alcoholic and PD brain.

Alcohol consumption and risk for Parkinson's disease: a systematic review and meta-analysis

The possibility that alcohol consumption should be considered as a "protective factor" for Parkinson's disease (PD) has been suggested by several case-control studies. However, other case-control studies and data from prospective longitudinal cohort studies have been inconclusive. We carried out a systematic review which included all the eligible studies published on PD risk related with alcohol consumption, and conducted a meta-analysis according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. The systematic review was performed using two databases, and the meta-analysis of the eligible studies with the software Meta-Disc1.1.1. Heterogeneity between studies was tested with the Q-statistic. The meta-analysis included 26 eligible retrospective case-control studies (8798 PD patients, 15,699 controls) and 5 prospective longitudinal cohort studies (2404 PD patients, 600,592 controls) on alcohol consumption and PD. In retrospective case-control studies the frequency of PD patients never drinkers was higher and the frequency of heavy + moderate drinkers was lower [diagnostic OR (95% CI) 1.33(1.20-1.48) and 0.74(0.64-0.85)], respectively, when compared to healthy controls. In contrast, in prospective studies, the differences were not significant with the exception of a trend towards a higher frequency of non-drinkers in PD women and a significantly lower frequency of moderate + heavy drinkers in PD men in those studies which stratified data by gender. The present meta-analysis suggests an inverse association between alcohol consumption and PD, which is supported by the results of case-control studies but not clearly by prospective ones.

Toxin-Induced Movement Disorders

Toxins can be cited as a cause of several movement disorders, but this association is rare and the resultant syndromes usually include additional signs that are not typical for the idiopathic movement disorders. Most instances of confirmed toxin-induced movement disorders show lesions on CT and MRI scans of cortical or subcortical structures. A common underlying element in these toxin-induced syndromes is the development of lesions primarily in the pallidum and striatum. Because many toxins result in lesions affecting these structures, a selective vulnerability to hypoxic or metabolic insults has long been postulated. The susceptibility of these structures may relate to a number of factors, including the pattern of oxidative metabolism, heavy metal concentration, vascular perfusion, and neuronal innervation. Finally, in addition to causing disability, certain neurotoxins have led to a better understanding of human disease through the development of research models. As an example, the MPTP model has not only provided an animal model to study therapeutic strategies in PD but has also contributed important insights into the mechanism of neuronal degeneration.

Joint analysis of the NACP-REP1 marker within the alpha synuclein gene concludes association with alcohol dependence

Various studies have linked alcohol dependence phenotypes to chromosome 4. One candidate gene is NACP (non-amyloid component of plaques), coding for alpha synuclein. Recently, it has been shown that alpha synuclein mRNA is increased in alcohol-dependent patients within withdrawal state. This increase is significantly associated with craving, especially obsessive craving. On the basis of these observations, the present study analysed two polymorphic repeats within the NACP gene. We found highly significant longer alleles of NACP-REP1 in alcohol-dependent patients compared with healthy controls (Kruskal-Wallis test, chi(2)=99.5; df=3, P<0.001). In addition, these lengths significantly correlate with levels of expressed alpha synuclein mRNA (chi(2)=8.83; df=2, P=0.012). The present results point to a novel approach for a genetic determination of craving, a key factor in the genesis and maintenance not only of alcoholism but also of addiction in general.

Parkinsonism in alcohol withdrawal: case report and review of the literature

A case of severe, acute parkinsonism occurring in a 60-year-old man after cessation of chronic alcohol consumption, is reported. He recovered completely in 3 months without specific therapy. The literature on alcohol withdrawal parkinsonism including nine other cases, is reviewed.

Risk-factors for Parkinson's disease: case-control study in the province of Cáceres, Spain

This case-control study, performed in a mixed rural and urban province, of 74 patients with Parkinson's disease (PD) and 148 unselected age and sex-matched controls, attempted to look possible risk factors for PD. Rural living, well-water drinking, positive family history for PD and postural tremor, were associated to an increased risk for PD, with results regarding exposure to pesticides near to statistical significance. Alcohol-drinking habit in males were associated to a decreased risk for PD, with results regarding cigarette-smoking habit in males near to statistical significance. We did not find association between the risk for PD and the following variables: 1) exposure to industrial toxins; 2) agricultural work; 3) cranial trauma; 4) previous common illnesses including some infections, arterial hypertension, diabetes mellitus, coronary heart disease and thyroid disease; 5) coffee and tea drinking habits.

Premorbid smoking, alcohol consumption, and coffee drinking habits in Parkinson's disease: a case-control study

A number of studies have reported lower cigarette consumption in patients with Parkinson's disease (PD) previous to onset of the disease. In an attempt to determine whether there existed a "premorbid attitude" by patients against the use of socially accepted "drugs," the premorbid tobacco, alcohol, and coffee consumption habits were compared in 128 PD patients and 256 controls. Patients and controls were selected by case control method and were recruited from the same health area and socioeconomic stratum. In males, the habits of smoking more than 10 cigarettes/day (p < 0.001) and drinking more than 50 g/day of alcohol (p < 0.001) were significantly less frequent in the PD patients than in the controls, but the differences in coffee consumption were nonsignificant. In females behavior did not differ significantly between the PD group and the controls for any of the three habits. There was no correlation between the amount of smoking and alcohol drinking and age at onset of PD or current Hoehn and Yahr's staging. Our results suggest the existence of a premorbid personality in males with PD, possibly conditioning a restrictive attitude toward the consumption of such toxic substances as tobacco and alcohol, yet a more tolerant attitude toward habits more widely accepted socially, like coffee consumption.

Alcohol induced Parkinsonism in an ex-pugilist

The case of an ex-pugilist who developed a reversible Parkinsonian syndrome in response to ethanol intoxication, is described. The relationship between ethanol abuse and altered function in the nigro-striatal system is examined, and the relationship to boxing encephalopathy is reviewed. The patient described was the third neurological casualty in a family of boxing brothers, and suggestions are made regarding the potential dangers of this sport. The syndrome of alcohol induced Parkinsonism in an ex-pugilist has not previously been described in the literature.

Drug-induced parkinsonism and other movement disorders

This is a review of reserpine, haloperidol, and various phenothiazines that produce parkinsonism and other movement disorders. The by-products of illicit meperidine synthesis, MPTP and its more sinister companion, MPP, are also discussed. Movement disorders, transient or fixed, frank parkinsonism and/or dyskinesia, due to a variety of other medications and toxic agents are included. These are methanol, lithium, methyldopa, antimetabolites, antidepressants, sympathomimetic anorexiants, some types of antihistamines, and various combinations of agricultural chemicals.

Parkinsonism in alcohol withdrawal: a follow-up study

Transient parkinsonism associated with alcohol intake and withdrawal has previously been described. We followed-up three patients with acute alcohol withdrawal-induced parkinsonism 9-11 years after their initial presentation. None showed any evidence of parkinsonism at follow-up. This suggests that withdrawal-induced parkinsonism is caused by a completely reversible abnormality in nigrostriatal dopamine transmission, which is unaccompanied by underlying nigral degeneration, as we had previously hypothesized.

Which factors influence age at onset and rate of progression in Huntington's disease?

Fifty-one families of patients affected with Huntington's chorea were interviewed with respect to age at onset, symptoms at onset and course of the disease. The interview further comprised questions pertinent to line of transmission, socio-economic status, housing, previous illnesses and pregnancy and stillbirth. Since the study was set up as a fishing expedition detailed quantitative information was gathered on many life-style factors including eating, drinking and smoking habits. In adult age onset cases earlier age at onset correlated with lower rate of progression. Line of transmission was of no influence on age at onset in cases with onset above 20 years. No statistically significant relationship was found between any factor studied and age at onset, except for the intake of milk. Higher previous milk intake was associated with earlier ages at onset. This finding is critically discussed. No difference was found between the respective ages at onset of conduct disorders and affective disorders. This suggests that they are both associated with the Huntington gene.

Special aspects of human alcohol withdrawal

There are still surprising gaps in our knowledge of alcohol withdrawal. While quantitative alcohol consumption accounts for about one third of the variability in severity of acute withdrawal, there is little systematic knowledge about the other factors involved. Thus, we cannot precisely predict the severity of withdrawal in individual patients. Controversy exists as to the role of medical vs. social detoxification approaches to acute withdrawal, the influence of acute withdrawal and its treatment on the long-term outcome of alcoholism, and the importance (or even existence) of chronic withdrawal. There is little systematic data to guide withdrawal treatment in special clinical settings, e.g., with concurrent medical or psychiatric illness or with mixed substance dependence. This chapter reviews the published literature, tries to point out methodological and conceptual problems, and suggests areas for future research.

Association between essential tremor and Parkinson's disease

To examine a possible relationship of essential tremor to Parkinson's disease (PD), 130 patients with essential tremor were studied. Twenty-five patients had both essential tremor and PD. These 25 patients were matched for age and duration of PD symptoms with 25 patients who had idiopathic PD. Bradykinesia, postural instability, and gait difficulty were more severe in the patients with idiopathic PD. Degree of tremor, rigidity, and functional disability did not differ in the two groups. The prevalence of PD in the population with essential tremor was 24 times greater than expected. This study suggests that some patients with essential tremor have a genetically increased risk for PD.

Extrapyramidal disorders: a possible underlying mechanism

In vivo and in vitro studies have been presented to suggest an interrelationship between drugs used in the management of, or known for their induction of extrapyramidal disorder and certain dehydrogenase enzymes involved in this metabolic pathway of the biogenic amines. This relationship is discussed to advance a tentative hypothesis explaining a possible underlying mechanism and to provide an explanation for the implication of alcohol consumption in worsening of extrapyramidal symptoms during certain pharmacotherapy. The major neutral metabolites of the biogenic amines acted as substrate to or induced rat liver alcohol dehydrogenase (L-ADH) and drugs used in the management of tardive dyskinesia similarly induced L-ADH. This induction of L-ADH could enhance the metabolic biotransformation of the neutral metabolites of the monoamines. Conversely, drugs known to evoke extrapyramidal dyskinesias inhibited rat liver aldehyde dehydrogenase (L-ALDH). This inhibition of ALDH may give rise to toxic condensation products between biogenic amine aldehydes and their precursors which may be implicated in certain dyskinesias. It is proposed that one of the mechanisms underlying the biogenic amine involvement in the pathogenesis of certain extrapyramidal diseases may include a critical balance between their reductive and oxidative routes of metabolism.