Smoking and cognitive function in Parkinson's disease

Subjective Cognitive Decline in Women with Features Suggestive of Prodromal Parkinson's Disease

BACKGROUND

Cognitive deficits can be present in the prodromal phase of Parkinson's disease (PD). Subjective cognitive decline (SCD) may contribute to identifying individuals with prodromal PD.

OBJECTIVE

The objective of this study was to examine whether SCD is more likely to be present in women with features suggestive of prodromal PD compared with women without these features.

METHODS

The study population comprised 12,427 women from the Nurses' Health Study selected to investigate prodromal PD. Prodromal and risk markers of PD were assessed via self-administered questionnaires. We evaluated the association of hyposmia, constipation, and probable rapid eye movement sleep behavior disorder, three major features of prodromal PD, with SCD, adjusting for age, education, body mass index, physical activity, smoking, alcohol, caffeine intake, and depression. We also explored whether SCD was associated with the probability of prodromal PD and conducted additional analyses using data from neurocognitive tests.

RESULTS

Women experiencing the three examined nonmotor features had the worst mean SCD score and the highest odds of poor subjective cognition (odds ratio [OR] = 1.78; 95% confidence interval [CI], 1.29-2.47). This association persisted when women with objective cognitive deficits were excluded from analyses. SCD was also more common in women with a probability of prodromal PD ≥0.80, particularly among those aged younger than 75 years (OR of poor subjective cognition = 6.57 [95% CI, 2.43-17.77]). These observations were consistent with the results from analyses using neurocognitive tests, where a worse global cognitive performance was observed among women with three features.

CONCLUSIONS

Our study suggests that self-perceived cognitive decline can be present during the prodromal phase of PD. © 2023 International Parkinson and Movement Disorder Society.

Coffee, smoking and aspirin are associated with age at onset in idiopathic Parkinson's disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder. Genetic modifiers, environmental factors and gene–environment interactions have been found to modify PD risk and disease progression. The objective of this study was to evaluate the association of smoking, caffeine and anti-inflammatory drugs with age at onset (AAO) in a large PD cohort. A total of 35,963 American patients with idiopathic PD (iPD) from the Fox Insight Study responded to health and lifestyle questionnaires. We compared the median AAO between different groups using the non-parametric Mann–Whitney U test. Non-parametric Spearman’s correlation was used for correlation assessments and regression analysis was used to assess interaction between variables. We found that smoking (p < 0.0001), coffee drinking (p < 0.0001) and aspirin intake (p < 0.0001) show an exploratory association with AAO in PD, that was further supported by multivariate regression models. The association of aspirin with PD AAO was replicated in another cohort (EPIPARK) (n = 237 patients with PD).

Cognitive function in men with non-motor features of Parkinson's disease

Objective

Subtle cognitive deficits can occur during the prodromal phase of Parkinson’s disease (PD), commonly in conjunction with hyposmia. However, little is known about the association between cognitive function and other features suggestive of prodromal PD. We evaluated the association of non-motor prodromal PD features, including hyposmia, constipation and probable REM sleep behaviour disorder (pRBD), with objective measures of cognitive function and self-reported cognitive decline.

Methods

The study population comprised 804 men who responded to a telephone cognitive interview in 2016–2017. Participants included 680 individuals with hyposmia, of whom 45 had confirmed PD, and 124 men without hyposmia. Among these men, we evaluated objective cognitive function and subjective cognitive decline to determine whether the presence of non-motor features of prodromal PD was associated with cognitive functioning. Analyses were adjusted for age, physical activity, body mass index, smoking status and coffee consumption.

Results

Individuals with non-motor features of prodromal PD had worse objective and subjective cognitive performance relative to men without non-motor features. Cognitive impairment was particularly prevalent among individuals with concurrent hyposmia, pRBD and constipation (multivariate-adjusted OR=3.80; 95% CI 1.52 to 9.47 for objective poor cognitive function; OR=8.71; 95% CI 3.18 to 23.83 for subjective cognitive decline). As expected, both objective (OR=7.91) and subjective (OR=17.42) cognitive impairment were also more common among men with confirmed PD.

Conclusions

Our study suggests that cognition is commonly affected in individuals with non-motor prodromal PD features, particularly when multiple of these features are present.

Modifiable vascular risk factors, white matter disease and cognition in early Parkinson's disease

BACKGROUND AND PURPOSE

Dementia in Parkinson's disease (PD) is common and disabling. Identification of modifiable risk factors for it is essential. Vascular risk factors (VRFs) may be associated with cognitive decline in early PD. Biomarkers that serve as surrogates of the long-term effect of VRFs on PD are needed. To that end, we aimed to quantitate white matter hyperintensities (WMH) in early PD, measure associations with VRFs and examine relationships between WMH and longitudinal cognition.

METHODS

Participants in the Parkinson's Progression Markers Initiative study (141 patients with PD, 63 healthy controls) with adequate baseline structural brain magnetic resonance imaging data were included. Hypertension and diabetes history, and body mass index were combined to create a vascular risk score. WMH were quantitated via automated methods. Cognition was assessed annually with a comprehensive test battery.

RESULTS

In the PD group, vascular risk score was associated with WMH for total brain (β = 0.210; P = 0.021), total white matter (β = 0.214; P = 0.013), frontal (β = 0.220; P = 0.002) and temporal (β = 0.212; P = 0.002) regions. Annual rate of change in global cognition was greater in those with higher vascular risk score (β = -0.040; P = 0.007) and greater WMH (β = -0.029; P = 0.049). Higher temporal WMH burden was associated with great decline over time in verbal memory (β = -0.034; P = 0.031).

CONCLUSIONS

In early PD, modifiable VRFs are associated with WMH on brain magnetic resonance imaging. Temporal WMH burden predicts decline in verbal memory. WMH may serve as a surrogate marker for the effect of VRFs on cognitive abilities in PD.

The influence of vascular risk factors on cognitive function in early Parkinson's disease

OBJECTIVES

Hypertension, dyslipidemia, diabetes, and obesity are well-established risk factors for cognitive impairment and dementia in older adults. In contrast, previous studies that have assessed the impact of vascular risk factors (VRFs) on cognition in Parkinson's disease (PD) have had methodological limitations and reported conflicting findings. We address this question in a large well-characterized cohort of de novo PD patients.

METHODS

A total of 367 untreated and non-demented patients aged 50 years and older with early PD (H&Y = 1.0-2.0) underwent a comprehensive clinical and neuropsychological assessment at baseline and 24 months later. A series of linear mixed models were used to determine the effects of VRFs on cognition while controlling for patient and disease characteristics. The outcomes included norm-referenced Z-scores of global cognition, visuospatial skills, verbal episodic memory, semantic verbal fluency, attention, and working memory tests.

RESULTS

A longer history of hypertension and a higher pulse pressure were significant predictors of lower Z-scores on immediate and delayed free recall, recognition, and verbal fluency tests. On average, every 10 mmHg increase in pulse pressure was associated with a 0.08 reduction on the cognitive Z-scores. The effects were independent of age, education, disease duration, motor impairment, medication, and depressive symptoms. Other VRFs were not associated with cognitive outcomes.

CONCLUSIONS

Our results are consistent with previous studies suggesting that hypertension exerts a detrimental effect on memory and verbal fluency in early PD. Management of blood pressure and cardiovascular health may be important to reduce risk of cognitive decline in PD. Copyright © 2017 John Wiley & Sons, Ltd.

Air pollution and Parkinson's disease - evidence and future directions

Parkinson's disease (PD) is a neurodegenerative disease of unknown etiology that is thought to be caused by a complex combination of environmental and/or genetic factors. Air pollution exposure is linked to numerous adverse effects on human health, including brain inflammation and oxidative stress, processes that are believed to contribute to the development and progression of PD. This review provides an overview of recent advances in the epidemiology of air pollution and PD, including evidence of the effects of various pollutants (ozone, PM10, PM2.5, PM2.5-10, NOx, NO2, CO, traffic air pollution, second-hand smoking) on PD risk. Based on this evidence, promising opportunities for future research are outlined, including: (1) studies of smaller particle sizes that cross the blood-brain barrier, (2) studies of the effects of air pollution on PD mortality and/or progression; (3) studies of interactions of air pollution with gene environment and other environmental factors.

Smoking history is associated to cognitive impairment in Parkinson's disease

INTRODUCTION

Patients with Parkinson's disease (PD) are more likely to suffer from cognitive impairment and dementia than healthy older adults. The aim of this study was to investigate smoking history as a risk factor for cognitive decline in PD.

METHOD

One hundred thirty-nine PD patients aged 50 years and older (Hoehn and Yahr = 1-3) were recruited from a clinical database. Global cognitive function was assessed with the Mini-Mental State Examination (MMSE) and smoking history was investigated as part of a standard clinical interview. A multiple linear regression analysis was used to develop a model for predicting participants' MMSE scores from age, education, Hoehn and Yahr stage, disease duration, the number of vascular risk factors and the number of smoking pack-years.

RESULTS

The regression model significantly accounted for 22.9% of the variance in MMSE scores. Significant predictors were education (β = .312, p < .001), age (β = -.215, p = .013) and total smoking pack-years (β = -.180, p = .029). In former smokers, the number of years since quitting had no effect on global cognition and there were no significant difference between patients who had quit smoking more than 10 years ago and those who had quit less than 10 years ago, F(1, 63) = 1.72, p = .195.

CONCLUSION

Smoking history was associated to global cognitive impairment in PD even in patients who had quit smoking. These results are in line with findings in healthy older adults that have linked smoking to cognitive impairment, global brain atrophy and functional changes. Future studies should consider a broader assessment of cognitive functions.

Non-Motor Correlates of Smoking Habits in de Novo Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) subjects are less likely to ever smoke and are more prone to quit smoking, as compared to controls. Therefore, smoking habits can be considered part of the non-motor phenotype, preceding the onset of motor PD by several years.

OBJECTIVE

To explore non-motor symptom (NMS) correlates of smoking habits in de novo PD.

METHODS

This cross-sectional study included 281 newly diagnosed, drug-naïve PD subjects, recruited in Naples (Italy) and in Kassel (Germany). All subjects completed the NMS Questionnaire (NMSQ), and were investigated for smoking status (never, current and former smokers) and intensity (pack-years).

RESULTS

140 PD subjects never smoked, 20 currently smoked, and 121 had quit smoking before PD diagnosis. NMSQ total score did not associate with smoking status, but with smoking intensity (p = 0.028; coefficient = 0.088). A multinomial logistic regression stepwise model presenting never smoking as reference, selected as NMSQ correlates of current smoking: sex difficulties (p = 0.002; OR = 5.254), daytime sleepiness (p = 0.046; OR = 0.085), insomnia (p = 0.025; OR = 0.135), and vivid dreams (p = 0.040; OR = 3.110); and of former smoking: swallowing (p = 0.013; OR = 0.311), nausea (p = 0.027; OR = 7.157), unexplained pains (p = 0.002; OR = 3.409), forgetfulness (p = 0.005; OR = 2.592), sex interest (p = 0.007; OR = 0.221), sex difficulties (p = 0.038; OR = 4.215), and daytime sleepiness (p = 0.05; OR = 0.372). An ordinal logistic regression stepwise model selected as NMSQ correlates of smoking intensity: nocturnal restlessness (p = 0.027; coefficient = 0.974), and leg swelling (p = 0.004; coefficient = 1.305).

CONCLUSIONS

Certain NMSs are associated with different smoking status and intensity, suggesting a variety of adaptive mechanisms to cigarette smoking.

Predictors of dementia in Parkinson's disease; findings from a 5-year prospective study using the SCOPA-COG

OBJECTIVE

Aim of this study was to identify risk factors for the development of dementia in patients with Parkinson's disease (PD).

METHODS

A broad range of motor and non-motor features was assessed at baseline and the following five years in 406 PD patients. Cross-sectional analyses of baseline data and longitudinal analyses of follow-up data were performed to identify risk factors for dementia.

RESULTS

Thirty-two percent of patients (n = 129) had dementia at baseline, while 26% of patients (n = 68) without dementia at baseline developed dementia during follow-up. Univariate survival analysis showed that higher age, fewer years of education, longer disease duration, higher age-at-onset, higher levodopa dose, higher Hoehn & Yahr stage, presence of dyskinesias, excessive daytime sleepiness (EDS), presence of hallucinations, and more severe autonomic and depressive symptoms were associated with an increased risk of dementia. Higher baseline Postural-Instability-and-Gait-Difficulty scores were also associated with an increased risk of dementia, whereas no effect of tremor severity was found. These findings largely corresponded with the variables that were associated with the presence of dementia at baseline. In a stepwise regression model, higher age at baseline, fewer years of education, higher daily levodopa dose and excessive daytime sleepiness (EDS) emerged as independent risk factors of future dementia.

CONCLUSIONS

In this large prospective cohort study, we identified a combination of potentially interacting risk factors for dementia in PD that are associated with higher age and more advanced disease.

History of smoking and olfaction in Parkinson's disease

OBJECTIVE

Olfactory dysfunction is the most common pre-motor symptom in Parkinson's disease (PD), and smoking is known to be associated with lower risk of PD. This study tested the hypothesis that smoking is associated with better olfaction in PD.

METHODS

Smoking history was obtained from 76 PD subjects (22 with a history of smoking [smokers], 54 who never smoked [nonsmokers]), and 70 controls (17 smokers, 53 nonsmokers). Olfaction was assessed using the 40-item University of Pennsylvania Smell Identification Test (UPSIT). The olfactory scores between groups and subgroups were compared using analysis of covariance with adjustment for age, gender, and monoamine oxidase B (MAO-B) inhibitor usage.

RESULTS

Overall the olfactory score was lower in PD compared with controls (olfactory scores: 21.5 vs. 33.5, P < 0.0001). Among controls, there was no significant difference in olfaction between smokers and nonsmokers (olfactory scores, 33.2 vs. 34.2; P = 0.95). Among PD subjects, however, smokers scored significantly better regarding olfaction compared with nonsmokers (olfactory scores: 24.4 vs. 19.9, P = 0.02).

CONCLUSIONS

These data suggest that a history of smoking is associated with better olfaction among PD patients. The finding may be related to why smoking may be protective against PD. Further studies are needed to confirm this finding and investigate the underlying mechanisms.

Exposure to environmental toxicants and pathogenesis of amyotrophic lateral sclerosis: state of the art and research perspectives

There is a broad scientific consensus that amyotrophic lateral sclerosis (ALS), a fatal neuromuscular disease, is caused by gene--environment interactions. In fact, given that only about 10% of all ALS diagnosis has a genetic basis, gene-environmental interaction may give account for the remaining percentage of cases. However, relatively little attention has been paid to environmental and lifestyle factors that may trigger the cascade of motor neuron degeneration leading to ALS, although exposure to chemicals--including lead and pesticides-agricultural environments, smoking, intense physical activity, trauma and electromagnetic fields have been associated with an increased risk of ALS. This review provides an overview of our current knowledge of potential toxic etiologies of ALS with emphasis on the role of cyanobacteria, heavy metals and pesticides as potential risk factors for developing ALS. We will summarize the most recent evidence from epidemiological studies and experimental findings from animal and cellular models, revealing that potential causal links between environmental toxicants and ALS pathogenesis have not been fully ascertained, thus justifying the need for further research.

A Critical Review of the Use of Telephone Tests to Identify Cognitive Impairment in Epidemiology and Clinical Research

We reviewed the use of telephone tests to identify cognitive impairment. We searched PubMed for epidemiological studies and clinical trials reporting the use of telephone tests to identify cognitive impairment. Validation studies and papers published more than 10 years ago were excluded. A total of 132 abstracts were identified, from which 19 epidemiological studies and four clinical trials were selected. Telephone tests were found to reduce selection bias in epidemiology by including people over large areas and facilitating follow-up in longitudinal studies. The most widely used tests were the Telephone Interview for Cognitive Status (TICS) and its modified version, the TICSm. Interviewing a proxy was included in most of the studies to compensate for the unavailability of some participants because of deafness, disease or death. In the epidemiological studies, results of telephone tests were seldom confirmed by a medical examination. Telephone screening for cognitive impairment to identify individuals eligible for clinical trials is impeded by low efficiency and lack of sensitivity for separating early pathological cognitive impairment from dementia and normal ageing.

The epidemiology of dementia associated with Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative illness after Alzheimer's disease (AD). Cognitive impairment and dementia are common features in PD and characterized by a wide range of cognitive deficits distinct from those seen in AD. Mild cognitive impairment occurs even early in PD and is associated with shorter time to dementia. The purpose of this review is to present recent findings on clinical aspects of dementia in PD and to elucidate underlying clinical and neurobiological risk factors.

The epidemiology of dementia associated with Parkinson disease

Several recent studies have shown that dementia is common in Parkinson's disease (PD), and that in some patients, cognitive impairment occurs even at the time of diagnosis. The point prevalence of dementia in PD is close to 30% and the incidence rate is increased 4-6 times as compared to controls. The cumulative prevalence is very high, at least 75% of PD patients who survive for more than 10 years will develop dementia. The mean time from onset of PD to dementia is approximately 10 years. However, there are considerable variations, and some patients develop dementia early in the disease course. Earlier onset of dementia is associated with more structural brain changes. The most established risk factors for early dementia are old age, severity of motor symptoms, in particular postural and gait disturbances, mild cognitive impairment and visual hallucinations. The genetic contributions to dementia are currently not clear and need to be explored in future studies.

Smoking, nicotine and neuropsychiatric disorders

Tobacco smoking is an extremely addictive and harmful form of nicotine (NIC) consumption, but unfortunately also the most prevalent. Although disproportionately high frequencies of smoking and its health consequences among psychiatric patients are widely known, the neurobiological background of this epidemiological association is still obscure. The diverse neuroactive effects of NIC and some other major tobacco smoke constituents in the central nervous system may underlie this association. This present paper summarizes the pharmacology of NIC and its receptors (nAChR) based on a systematic review of the literature. The role of the brain's reward system(s) in NIC addiction and the results of functional and structural neuroimaging studies on smoking-related states and behaviors (i.e. dependence, craving, withdrawal) are also discussed. In addition, the epidemiological, neurobiological, and genetic aspects of smoking in several specific neuropsychiatric disorders are reviewed and the clinical relevance of smoking in these disease states addressed.

Biomarkers for Parkinson's [corrected] disease: tools to assess Parkinson's disease onset and progression

Reliable and well-validated biomarkers for PD to identify individuals "at risk" before motor symptoms, accurately diagnose individuals at the threshold of clinical PD, and monitor PD progression throughout its course would dramatically accelerate research into both PD cause and therapeutics. Biomarkers offer the potential to provide a window onto disease mechanism, potentially generating therapeutic targets for disease. In particular, biomarkers enable investigation of the premotor period of PD before typical symptoms are manifest, but while degeneration has already begun. Given the multiple genetic causes for PD already identified, the marked variability in the loss of dopaminergic markers measured by imaging at motor symptom onset and the clear heterogeneity of clinical symptoms in PD onset and clinical progression, it is likely many biomarkers with a focus ranging from clinical symptoms to PD pathobiology to molecular genetic mechanisms will be necessary to fully map PD risk and progression. Biomarkers are also critical in new drug development for PD, both in early validation studies to assess drug dosing and to determine drug penetrance into the brain, and in later efficacy studies to complement PD clinical outcomes. During the past two decades, much progress has been made in identifying and assessing PD biomarkers, but as yet, no fully validated biomarker for PD is currently available. Nonetheless, there is increasing evidence that molecular genetics, focused -omic (proteomic, metabolomic, and transcriptomic) assessment of blood and cerebrospinal fluid, and advanced in vivo brain imaging will provide critical clues to assist in the diagnosis and medical management of PD patients.