What are the risk factors for Parkinson’s disease? 1, dairy products According to the study: Parkinson’s disease risk is increased in individuals with higher milk and dairy product intake. A recent meta-analysis showed that the association between higher dairy intake and Parkinson’s disease risk was stronger in men. 2. Pesticides One hypothesis is that exposure to pesticides and other chemical contaminants increases the risk of Parkinson’s disease, due to the discovery that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has neurotoxic effects that can be converted to pre-Parkinson’s disease molecules in the body, with a structure similar to that of the herbicide paraquat. Agricultural health studies have found a positive correlation between disease risk and exposure to pesticides known to affect mitochondrial complex I (including rotenone) or cause oxidative stress (including paraquat). Overall, the evidence for increased risk of Parkinson’s disease from pesticide exposure is relatively strong, but the association between that risk and specific compounds is uncertain. 3. Cancer There is evidence in the literature that melanoma patients have an increased risk of Parkinson’s disease. In a large Danish study, a diagnosis of melanoma was associated with a 44% increased risk of developing Parkinson’s disease. A similar association was seen in a Swedish national study. One study found an increased risk of Parkinson’s disease in individuals with a family history of melanoma, a finding that suggests a common genetic predisposition, but the association between melanoma risk alleles and Parkinson’s disease has not been confirmed, and the known Parkinson’s disease susceptibility alleles do not appear to be associated with melanoma risk. 4. Traumatic brain injury Traumatic brain injury leads to disruption of the blood-brain barrier, persistent encephalitis, decreased mitochondrial function, and accumulation of alpha-synuclein in the brain, all of which elevate the incidence of Parkinson’s disease after this type of injury. However, the results of several studies suggest that Parkinson’s disease risk appears to increase immediately after traumatic brain injury and gradually decline over time. 5. Body mass index and diabetes An association between body mass index (BMI) and Parkinson’s disease risk was not found in most longitudinal studies, and in one meta-analysis, a 5 kg/m2 increase in BMI was associated with an overall RR of 1.0 (95% CI 0.9-1.1). However, in a Finnish cohort study, being overweight (ie, BMI 27-29.9) or obese (ie, BMI ≥30) was a strong risk factor for Parkinson’s disease (risk ratio [HR] 2.0 for each group compared with BMI <23). The risk of Parkinson's disease was higher in those with higher triceps skinfold thickness or waist-to-hip ratio, suggesting that fat distribution may be a better indicator of Parkinson's disease risk compared to overall body weight. A Finnish study showed that metabolic syndrome was associated with a 50% decreased risk of Parkinson's disease (RR 0.5, 95% CI 0.30-0.83); this association was mainly due to elevated fasting glucose (0.52, 0.3-0.89; p=0.02). In contrast, the Finnish Cohort Study, the Danish and Chinese Taiwan Database Study, the Physicians' Health Study, and the NIH-AARP Cohort Study all reported a significantly increased risk of Parkinson's disease in patients with type 2 diabetes. However, in two large prospective US cohorts, diabetes was not associated with Parkinson's disease risk. These conflicting results suggest that the relationship between insulin resistance and Parkinson's disease is complex and may be influenced by other factors, such as hyperuricemia, a risk factor for type 2 diabetes but negatively associated with Parkinson's disease risk. In addition, the risk of Parkinson's disease in diabetic patients is also reduced by the use of antidiabetic drugs, such as metformin, exenatide or dipeptidyl peptidase inhibitors. 6, blood cholesterol and hypertension According to the study: Parkinson's disease risk decreased with increasing self-reported blood cholesterol levels, but not with hypercholesterolemia, history of hypertension diagnosis or blood pressure. These inconsistent results suggest the presence of uncertain confounding or modifying factors mediating the association between blood cholesterol and Parkinson's disease risk. 7. Alcohol consumption Overall, the results of longitudinal studies suggest that the risk of Parkinson's disease is relatively lower in alcohol drinkers compared with non-drinkers. However, in a study based on the Swedish National Inpatient Registry, alcohol abuse (defined as an inpatient diagnosis of alcohol use disorder) was associated with an increased risk of Parkinson's disease. 8. Postmenopausal hormonal and reproductive factors The incidence of Parkinson's disease is higher in men than in women, suggesting the existence of hormonal determinants of Parkinson's disease risk. In the Cancer Prevention Study, women who reported using postmenopausal estrogenic drugs had a 33% higher risk of Parkinson's disease death than those who did not use these drugs. According to the study, there was no significant increase in the risk of Parkinson's disease among postmenopausal estrogen users. These findings suggest that postmenopausal estrogen use may be associated with an increased risk of Parkinson's disease, rather than a reduced risk. The association between estrogen use and Parkinson's disease risk may be modifiable by caffeine intake. 9. Other factors Evidence for many of the recognized risk factors for Parkinson's disease remains sparse or inconsistent, including early life factors such as season of birth, weight and parental age, and some infectious diseases such as measles (negative association), CNS infection, hepatitis C and Helicobacter pylori. Influenza virus has been shown to be associated with an increased risk of Parkinson's syndrome, but not Parkinson's disease. Manganese can cause Parkinson's syndrome, but its evidence for Parkinson's disease risk remains inconclusive. The Swedish study found a higher risk of Parkinson's disease in patients with concomitant autoimmune disease and in those of higher socioeconomic status, and a high risk of Parkinson's disease in those with lupus erythematosus in the Danish study. There is growing interest in the potential role of solvents (e.g., trichloroethylene) as adverse risk factors and digestive flora as modifiers of Parkinson's disease risk, but data from longitudinal studies are lacking.