Depression and the subsequent risk of Parkinson's disease in the NIH-AARP Diet and Health Study

Risk of Parkinson's disease following anxiety disorders: a nationwide population-based cohort study

BACKGROUND AND PURPOSE

Anxiety is potentially a pre-motor symptom of Parkinson's disease (PD). Our aim was to investigate the association between anxiety and subsequent PD risk in a population-based sample.

METHODS

A total of 174 776 participants, who were free of prior PD, dementia and stroke, were enrolled from Taiwan National Health Insurance Research Database between 1 January 2005 and 31 December 2005. The association between anxiety at the beginning of the study and the incidence of PD was examined using a Cox regression model. Information regarding comorbidities, especially depression, and concomitant medication use was adjusted in the proportional hazards models.

RESULTS

Over an average follow-up of 5.5 years, 2258 incident PD cases were diagnosed. After adjusting for age, sex, comorbidities and concomitant medication use, patients with anxiety were more likely to develop PD than subjects without anxiety [adjusted hazard ratio (HR) 1.38; 95% confidence interval (CI) 1.26-1.51]. Anxiety severity was dose-dependently associated with increased likelihood of PD: crude HR 1.27 (95% CI 1.11-1.44) for mild anxiety, 1.35 (95% CI 1.19-1.53) for moderate anxiety and 2.36 (95% CI 2.13-2.62) for severe anxiety (P < 0.0001). Results were similar after adjustment for age, sex, comorbid depression and other PD risk factors, and in the sensitivity analyses excluding participants with comorbid depression or with a PD diagnosis <3 years after anxiety diagnosis, and controlling for Charlson's scores.

CONCLUSIONS

The likelihood of developing PD was greater amongst patients with anxiety than patients without anxiety, and the severity of anxiety correlated with risk of PD.

Depression and subsequent risk of Parkinson disease: A nationwide cohort study

OBJECTIVE

To investigate the long-term risk of Parkinson disease (PD) after depression and evaluate potential confounding by shared susceptibility to the 2 diagnoses.

METHODS

The nationwide study cohort included 140,688 cases of depression, matched 1:3 using a nested case-control design to evaluate temporal aspects of study parameters (total, n = 562,631). Potential familial coaggregation of the 2 diagnoses was investigated in a subcohort of 540,811 sibling pairs. Associations were investigated using multivariable adjusted statistical models.

RESULTS

During a median follow-up period of 6.8 (range, 0-26.0) years, 3,260 individuals in the cohort were diagnosed with PD. The multivariable adjusted odds ratio (OR) for PD was 3.2 (95% confidence interval [CI], 2.5-4.1) within the first year of depression, decreasing to 1.5 (95% CI, 1.1-2.0) after 15 to 25 years. Among participants with depression, recurrent hospitalization was an independent risk factor for PD (OR, 1.4; 95% CI, 1.1-1.9 for ≥5 vs 1 hospitalization). In family analyses, siblings' depression was not significantly associated with PD risk in index persons (OR, 1.1; 95% CI, 0.9-1.4).

CONCLUSIONS

The time-dependent effect, dose-response pattern for recurrent depression, and lack of evidence for coaggregation among siblings all indicate a direct association between depression and subsequent PD. Given that the association was significant for a follow-up period of more than 2 decades, depression may be a very early prodromal symptom of PD, or a causal risk factor.

Premotor and nonmotor features of Parkinson's disease

PURPOSE OF REVIEW

This review highlights recent advances in premotor and nonmotor features in Parkinson's disease, focusing on these issues in the context of prodromal and early-stage Parkinson's disease.

RECENT FINDINGS

Although Parkinson's disease patients experience a wide range of nonmotor symptoms throughout the disease course, studies demonstrate that nonmotor features are not solely a late manifestation. Indeed, disturbances of smell, sleep, mood, and gastrointestinal function may herald Parkinson's disease or related synucleinopathies and precede these neurodegenerative conditions by 5 or more years. In addition, other nonmotor symptoms such as cognitive impairment are now recognized in incident or de-novo Parkinson's disease cohorts. Many of these nonmotor features reflect disturbances in nondopaminergic systems and early involvement of peripheral and central nervous systems, including olfactory, enteric, and brainstem neurons as in Braak's proposed pathological staging of Parkinson's disease. Current research focuses on identifying potential biomarkers that may detect persons at risk for Parkinson's disease and permit early intervention with neuroprotective or disease-modifying therapeutics.

SUMMARY

Recent studies provide new insights into the frequency, pathophysiology, and importance of nonmotor features in Parkinson's disease as well as the recognition that these nonmotor symptoms occur in premotor, early, and later phases of Parkinson's disease.

Meta-analyses on prevalence of selected Parkinson's nonmotor symptoms before and after diagnosis

Background

Nonmotor symptoms are common among patients with Parkinson’s disease (PD) and some may precede disease diagnosis.

Methods

We conducted a meta-analysis on the prevalence of selected nonmotor symptoms before and after PD diagnosis, using random-effect models. We searched PubMed (1965 through October/November 2012) for the following symptoms: hyposmia, constipation, rapid eye movement sleep behavior disorder, excessive daytime sleepiness, depression, and anxiety. Eligible studies were publications in English with original data on one or more of these symptoms.

Results

The search generated 2,373 non-duplicated publications and 332 met the inclusion criteria, mostly (n = 320) on symptoms after PD diagnosis. For all symptoms, the prevalence was substantially higher in PD cases than in controls, each affecting over a third of the patients. Hyposmia was the most prevalent (75.5% in cases vs. 19.1% in controls), followed by constipation (50% vs. 17.7%), anxiety (39.9% vs. 19.1%), rapid eye movement sleep behavior disorder (37.0% vs. 7.0%), depression (36.6% vs. 14.9%), and excessive daytime sleepiness (33.9% vs. 10.5%). We observed substantial heterogeneities across studies and meta-regression analyses suggested that several factors might have contributed to this. However, the prevalence estimates were fairly robust in several sensitivity analyses. Only 20 studies had data on any symptoms prior to PD diagnosis, but still the analyses revealed higher prevalence in future PD cases than in controls.

Conclusion

These symptoms are common among PD patients both before and after diagnosis. Further studies are needed to understand the natural history of nonmotor symptoms in PD and their etiological and clinical implications.

Electronic supplementary material

The online version of this article (doi:10.1186/2047-9158-4-1) contains supplementary material, which is available to authorized users.

Depression in Parkinson's disease

Depression is a frequent comorbid disorder of Parkinson's disease; however, little is known about its pathomechanisms. Although depression is an important factor negatively affecting the quality of life of parkinsonian patients, it often remains undiagnosed and therefore untreated. Furthermore, antidepressant therapy is problematic because of the need to combine antidepressant drugs with antiparkinsonian treatments. The present paper gives an overview of characteristic features of Parkinson's disease-associated depression, experimental studies on its animal models, potential mechanisms involved in its occurrence and possible strategies for treatment.

Individual and joint prevalence of three nonmotor symptoms of PD in the US general population

BACKGROUND

Some nonmotor symptoms may precede the clinical diagnosis of Parkinson's disease (PD) by years.

METHODS

We examined the individual and joint prevalence of depression, daytime sleepiness, and infrequent bowel movement among 10,477 participants of the US National Health and Nutrition Examination Surveys 2005-2008.

RESULTS

For all symptoms, the prevalence was higher in women than in men. Importantly, few participants had two or more symptoms: 1.3% at ages 20 to 29, 1.0% at 30 to 39, 1.2% at 40 to 49, 3.5% at 50 to 59, 1.7% at 60 to 69, 1.1% at 70 to 79, and 1.2% at ages 80 years or older in men; the corresponding prevalence in women was 3.1%, 5.2%, 5.7%, 4.1%, 3.1%, 2.3%, and 1.2%, respectively. In both men and women, depression was correlated with infrequent bowel movement and daytime sleepiness, but the latter two were mutually independent.

CONCLUSION

The presence of multiple nonmotor symptoms was uncommon in the general population and the prevalence was higher in women than in men.

Pramipexole but not imipramine or fluoxetine reverses the "depressive-like" behaviour in a rat model of preclinical stages of Parkinson's disease

Depression is a frequent comorbid disorder in Parkinson's disease and may antedate its motor symptoms. However, mechanisms underlying Parkinson's disease-associated depression are unknown and its current medication is insufficient. The aim of the present study was to compare antidepressant-like effects of imipramine, fluoxetine and pramipexole in a model of preclinical stages of Parkinson's disease in rats. 6-Hydroxydopamine was bilaterally injected into the ventrolateral region of the caudate-putamen in rats. This treatment induced moderate decreases in the levels of dopamine and its metabolites in the caudate-putamen, nucleus accumbens and frontal cortex and reduced the density of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra pars compacta and ventral tegmental area. The lesion increased immobility measured in the forced swimming test without influencing locomotor activity. Chronic (13 days) administration of pramipexole (1mg/kg sc/twice a day) reversed prolongation of the immobility time in lesioned animals but did not stimulate their locomotion. Chronic pramipexole activated dopaminergic transmission in the brain structures which might contribute to its effectiveness in the forced swimming test. In contrast, the 13-day administration of imipramine (10mg/kg ip/day) and fluoxetine (10mg/kg ip/day) did not shorten the immobility time in lesioned rats but reduced their locomotion. The present study indicates that already a moderate lesion of dopaminergic neurons induces "depressive-like" behaviour in animals which is reversed by chronic administration of the antiparkinsonian drug, pramipexole.

Psychiatric diseases predated the occurrence of Parkinson disease: a retrospective cohort study

PURPOSE

The influence of mental illness early in life on the subsequent risk of Parkinson disease (PD) and its clinical picture remain obscure. This study investigated the effects of psychiatric diseases on a subsequent PD diagnosis.

METHODS

We used the Longitudinal Health Insurance Database 2000 of Taiwan to identify 73,597 patients who visited ambulatory care centers or were hospitalized with a first-time diagnosis of anxiety, affective disorders, or schizophrenia between 2001 and 2003 as the study cohort. We also randomly selected 220,791 enrollees matched with the study cohort for comparison. Each patient was individually tracked for 6 years to identify a subsequent PD diagnosis. Stratified Cox proportional hazard regressions were performed for the analysis.

RESULTS

The incidence rate of PD per 1000 person-years was 4.91 (95% confidence interval [CI], 4.71-5.12) and 1.63 (95% CI, 1.56-1.70) for the psychiatric and comparison groups, respectively. Patients with psychiatric illnesses were more vulnerable to developing PD than nonpsychiatric individuals, exhibiting a 2.38-fold increased risk (95% CI, 2.23-2.53) after other covariates were considered. Furthermore, patients with schizophrenia exhibited the highest risk for developing PD.

CONCLUSIONS

We suggest effective monitoring of patients with psychiatric disturbances for potential long-term neurodegenerative diseases.

Research on the premotor symptoms of Parkinson's disease: clinical and etiological implications

BACKGROUND

The etiology and natural history of Parkinson's disease (PD) are not well understood. Some non-motor symptoms such as hyposmia, rapid eye movement sleep behavior disorder, and constipation may develop during the prodromal stage of PD and precede PD diagnosis by years.

OBJECTIVES

We examined the promise and pitfalls of research on premotor symptoms of PD and developed priorities and strategies to understand their clinical and etiological implications.

METHODS

This review was based on a workshop, Parkinson's Disease Premotor Symptom Symposium, held 7-8 June 2012 at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina.

DISCUSSION

Research on premotor symptoms of PD may offer an excellent opportunity to characterize high-risk populations and to better understand PD etiology. Such research may lead to evaluation of novel etiological hypotheses such as the possibility that environmental toxicants or viruses may initiate PD pathogenesis in the gastrointestinal tract or olfactory bulb. At present, our understanding of premotor symptoms of PD is in its infancy and faces many obstacles. These symptoms are often not specific to PD and have low positive predictive value for early PD diagnosis. Further, the pathological bases and biological mechanisms of these premotor symptoms and their relevance to PD pathogenesis are poorly understood.

CONCLUSION

This is an emerging research area with important data gaps to be filled. Future research is needed to understand the prevalence of multiple premotor symptoms and their etiological relevance to PD. Animal experiments and mechanistic studies will further understanding of the biology of these premotor symptoms and test novel etiological hypothesis.

Investigating emotions in Parkinson's disease: what we know and what we still don't know

Over the last decade, there has been an increasing attention to the role played by emotional processes in Parkinson's disease (PD). However, most of what is known in this area is based on research conducted in laboratory or clinical settings. In this article, the authors underline the need to expand our current knowledge of the psychological correlates of PD by investigating patients' everyday emotions in natural contexts. Specifically, the authors illustrate new research avenues based on the implementation of experience sampling methods. It is argued that these methods could permit future researchers to ecologically assess the frequency and intensity with which parkinsonian patients experience specific emotions (either negative or positive) during their everyday life, providing at the same time precious information on what are the most typical situations in which these emotions occur and on how patients behave in these circumstances. Potential practical implications associated with investigating these issues are discussed.

Cohort Profile: a population-based cohort to study non-motor symptoms in parkinsonism (EPIPARK)

Parkinson's disease is increasingly viewed as a complex disorder including a range of typical non-motor symptoms in addition to the cardinal motor signs. This cohort was set up in 2010 to investigate the specificity of non-motor symptoms for Parkinson's disease. For this, we included several control groups with decreasing contrast from Parkinson's disease patients. Group definitions ranged from healthy control subjects to those with suspected early motor signs of parkinsonism. Using a mailed questionnaire, we screened 5838 inhabitants of Lübeck, Germany, out of a target population of 10 000 citizens, enquiring about motor impairment, pain, quality of life, comorbidities, somatization and demographics. Based on this information, participants were assigned to screening groups, and selected participants were invited for in-person examination (n = 623). The examination included cognitive examinations, transcranial ultrasound, a brief psychiatric interview and a standardized motor examination that was used to assign examination groups. In addition, all participants answered questionnaires addressing depression, anxiety, sleep and quality of life. The first-year follow-up examination was performed either in person using the same protocol or via mailed questionnaires. This study is ongoing and publications are in preparation, but you may contact the first author (meike.kasten@neuro.uni-luebeck.de) with suggestions for collaboration or data requests.

Partial lesion of the dopaminergic innervation of the ventral striatum induces "depressive-like" behavior of rats

Depression is a frequent comorbid disorder in Parkinson's disease (PD) which may precede appearance of its motor symptoms by several years. Pathomechanisms underlying PD have been suggested to be responsible for the PD-related depression. The aim of the study was to examine the influence of a partial lesion of striatal dopaminergic terminals on the "depressive-like" behavior of rats in the forced swimming test (FS). 6-Hydroxydopamine (6-OHDA) was injected bilaterally into the ventro-lateral region of the caudate-putamen (CP) (3.75 μg/2.5 μl/side). The locomotor activity and behavior of rats in the FS were measured 2 and 4 weeks after the operation. The lesion extent was analyzed by biochemical and immunohistochemical methods. Two weeks after the operation, the 6-OHDA-treated rats displayed a prolonged immobility in the FS. This effect disappeared after 4 weeks. The locomotor activity was not influenced by 6-OHDA. Levels of dopamine, DOPAC and HVA were decreased in the nucleus accumbens (NAC) 2 weeks after 6-OHDA but were not changed in the CP, frontal cortex (FCX) and substantia nigra (SN). No significant effect of 6-OHDA on tyrosine hydroxylase-immunoreactivity in the CP and NAC were found. The present study indicates that a relatively small lesion of dopaminergic terminals in the ventral striatum, which does not produce any motor disturbances, may induce "depressive-like" symptoms.

Depression and quality of life in monogenic compared to idiopathic, early-onset Parkinson's disease

Quality of life (QoL) is decreased in PD and is linked with depression and anxiety. However, little is known about QoL in monogenic PD. Subjects with mutations in PD genes were recruited from ongoing family and genetic studies (manifesting carriers, n = 23; nonmanifesting carriers, n = 19). For comparison purposes, we included patients with idiopathic PD (IPD; n = 128; early onset, n = 38; late onset, n = 90), healthy controls (n = 127), and data on depressive symptoms of 144 patients with major depression (treated controls). Depression affected 31% of early-onset PD cases, 21% of late-onset cases, and 44% of manifesting carriers of mutations in PD genes, but was rare in the nonmanifesting carriers (7%) and healthy controls (5%). Subjects with Parkinson-associated depression reported fewer feelings of guilt or self-doubt than treated controls, but the occurrence of suicidal ideation was associated with severity of depression only. Social phobia (P = 0.018) and agoraphobia (P = 0.059) were more common in manifesting carriers than in any other group. QoL was decreased in the Parkinson groups, particularly in the early-onset cases (P < 0.001), and QoL correlated with depression in all analyses. In our study, monogenic and IPD cases were comparable in QoL and depression characteristics. The QoL and, possibly, overall prognosis of all PD patients can be improved by appropriate attention and treatment for depression, sleep impairments, and anxiety, even if the treatment of the motor problems cannot be further optimized.

Converting epidemiologic studies of cancer etiology to survivorship studies: approaches and challenges

There are nearly 12 million cancer survivors living in the United States, and the number continues to rise with ongoing improvements in treatment and screening. Assuring the long-term health of these patients poses both clinical and public health concerns. Survivorship research covers multiple aspects of life after a cancer diagnosis, including quality of life, acute and late effects of cancer treatment and mortality. Answering these questions requires a wide array of data, including information on the outcomes of interest, treatment history, and lifestyle. One potentially efficient approach to studying late effects and survivorship is to convert or extend existing epidemiologic studies of cancer etiology. In this article, we evaluate the different potential approaches for doing this and the challenges this entails. Our evaluation highlights the combinations of research topic and design most likely to succeed. We show that any question that relates to the existing information including prediagnosis lifestyle factors or genetics (if samples are available) could be efficiently studied, with an appropriate design. On the other hand, most, though not all converted studies would be ill-suited to the evaluation of the effect of treatment and postdiagnosis lifestyle changes. In terms of endpoints, hard outcomes including mortality and second cancers are more likely to be available within the existing study framework than other morbidities or quality of life. In light of the costs and time required to build new cohorts, appropriately leveraging the existing studies offers an important opportunity to gain new insights into cancer survivorship for both clinicians and patients.

Daytime napping, nighttime sleeping, and Parkinson disease

Preliminary evidence suggests that daytime sleepiness may predate clinical diagnosis of Parkinson disease. The authors examined daytime napping and nighttime sleeping durations, reported in 1996-1997 by 220,934 US NIH-AARP Diet and Health Study participants, in relation to Parkinson disease diagnoses at 3 clinical stages: established (cases diagnosed before 1995, n = 267), recent (1995-1999, n = 396), and prediagnostic (2000 and after, n = 770). Odds ratios and 95% confidence intervals were derived from multivariate logistic regression models. Longer daytime napping was associated with higher odds of Parkinson disease at all 3 clinical stages: the odds ratios comparing long nappers (>1 hour/day) with nonnappers were 3.9 (95% confidence interval: 2.8, 5.6) for established cases, 2.2 (95% confidence interval: 1.7, 3.0) for recent cases, and 1.5 (95% confidence interval: 1.2, 1.9) for prediagnostic cases. Further control for health status or nighttime sleeping duration attenuated the association for established cases but made little difference for recent or prediagnostic cases. In the nighttime sleeping analysis, a clear U-shaped association with Parkinson disease was observed for established cases; however, this association was attenuated markedly for recent cases and disappeared for prediagnostic cases. This study supports the notion that daytime sleepiness, but not nighttime sleeping duration, is one of the early nonmotor symptoms of Parkinson disease.

Parkinson's disease: the quintessential neuropsychiatric disorder

Although diagnosed by characteristic motor features, Parkinson's disease may be preceded, and is frequently accompanied by, a wide range of cognitive and neuropsychiatric features. In addition to the most commonly studied disorders of dementia, depression, and psychosis, other relatively common and clinically significant psychiatric complications include impulse control disorders, anxiety symptoms, disorders of sleep and wakefulness, and apathy. These problems may be underrecognized and are frequently undertreated. The emergent focus on nonmotor aspects of Parkinson's disease over the past quarter of a century is highlighted by a nonlinear increase in the number of articles published devoted to this topic. Although the development of newer antidepressants, atypical antipsychotics, and cholinesterase inhibitors in recent years has had a positive benefit on the management of these troublesome and distressing symptoms, responses are frequently suboptimal, and this remains an area of major unmet therapeutic need.