Parkinson's disease in Africa: A systematic review of epidemiologic and genetic studies.

Parkinson's disease (PD) occurs worldwide, but little is known about PD in Africa. We systematically reviewed publications on PD in Africa, with emphasis on epidemiologic and genetic studies. Articles published between 1944 and December 2004 were identified using several strategies. The studies emanated from 13 African countries (Kenya, Uganda, Tanzania, Ethiopia, Nigeria, Senegal, Ghana, Togo, Libya, Tunisia, Algeria, Zimbabwe, and South Africa). The publications fell into four categories: clinical series (n = 17), prevalence studies (n = 7), incidence studies (n = 1), and genetic studies (n = 3). The clinical series documented the occurrence of PD in Africa and described its clinical characteristics. The prevalence studies suggested some intracontinental geographic variation in PD prevalence. Overall, the prevalence figures and the incidence rates of PD in Africa appeared lower than those reported for European and North American populations. Few genetic studies of PD have been reported from Africa, and none in blacks. There are no case-control or cohort studies of PD reported from Africa. This review provides a summary of PD research in Africa over the past 60 years and highlights the information gaps and potential areas for future research.     

Nurr1‐Based Therapies for Parkinson's Disease

Previous studies have documented that orphan nuclear receptor Nurr1 (also known as NR4A2) plays important roles in the midbrain dopamine (DA) neuron development, differentiation, and survival. Furthermore, it has been reported that the defects in Nurr1 are associated with Parkinson's disease (PD). Thus, Nurr1 might be a potential therapeutic target for PD. Emerging evidence from in vitro and in vivo studies has recently demonstrated that Nurr1‐activating compounds and Nurr1 gene therapy are able not only to enhance DA neurotransmission but also to protect DA neurons from cell injury induced by environmental toxin or microglia‐mediated neuroinflammation. Moreover, modulators that interact with Nurr1 or regulate its function, such as retinoid X receptor, cyclic AMP‐responsive element‐binding protein, glial cell line‐derived neurotrophic factor, and Wnt/β‐catenin pathway, have the potential to enhance the effects of Nurr1‐based therapies in PD. This review highlights the recent progress in preclinical studies of Nurr1‐based therapies and discusses the outlook of this emerging therapy as a promising new generation of PD medication.     

Beliefs,knowledge and attitudes towards Parkinson's disease among a Xhosa speaking black population in South Africa: A cross-sectional study

IntroductionMany patients with Parkinson's disease (PD) in sub-Saharan Africa (SSA) are thought to be undiagnosed and untreated, leading to poor health outcomes. Increasing rates of diagnosis and treatment, with consequent improvements in the quality of life of people with PD in SSA requires an understanding of how PD is perceived and conceptualized within communities.MethodsA cross-sectional survey was conducted among a group of Xhosa speaking black South Africans. The survey involved the administration of questionnaires on beliefs, knowledge and attitudes about PD to the public, people with PD (PwPD) and traditional healers (THs).Results18% of the participants could identify PD through its symptoms. Mental illness, other diseases, stress, expressing strong emotions, consumption of certain foods or drinks and witchcraft were identified as possible causes of PD. PwPD and THs had a greater knowledge of PD than the public and greater age was a significant predictor of greater knowledge. The public and THs had a greater degree of concern about a range of symptoms of PD compared to PwPD.ConclusionThere is a striking lack of knowledge about PD amongst black South Africans. Almost half the members of the general public interviewed felt that PwPD should not live amongst their community, and a third considered that witchcraft could be a cause of PD. Finding ways to effectively educate members of a community about PD would make it easier for PwPD to adapt to their condition within their communities.     

Translating Evidence to Advanced Parkinson's Disease Patients: A Systematic Review and Meta-Analysis

In the advanced stages of Parkinson's disease (PD), patients frequently experience disabling motor complications. Treatment options include deep brain stimulation (DBS), levodopa-carbidopa intestinal gel (LCIG), and continuous subcutaneous apomorphine infusion (CSAI). Choosing among these treatments is influenced by scientific evidence, clinical expertise, and patient preferences. To foster patient engagement in decision-making among the options, scientific evidence should be adjusted to their information needs. We conducted a systematic review from the patient perspective. First, patients selected outcomes for a treatment choice: quality of life, activities of daily living, ON and OFF time, and adverse events. Second, we conducted a systematic review and meta-analysis for each treatment versus best medical treatment using Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). Finally, the evidence was transformed into comprehensible and comparable information. We converted the meta-analysis results into the number of patients (per 100) who benefit clinically from an advanced treatment per outcome, based on the minimal clinically important difference and the cumulative distribution function. Although this approach allows for a comparison of outcomes across the three device-aided therapies, they have never been compared directly. The interpretation is hindered by the relatively short follow-up time in the included studies, usually less than 12 months. These limitations should be clarified to patients during the decision-making process. This review can help patients integrate the evidence with their own preferences, and with their clinician's expertise, to reach an informed decision. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society     

Recent Advances in the Development of Stem-Cell-Derived Dopaminergic Neuronal Transplant Therapies for Parkinson's Disease

The last decade has seen exciting advances in the development of potential stem cell-based therapies for Parkinson's disease (PD), which have used different types of stem cells as starting material. These cells have been developed primarily to replace dopamine-producing neurons in the substantia nigra that are progressively lost in the disease process. The aim is to largely restore lost motor functions, whilst not ever being curative. We discuss cell-based strategies that will have to fulfill important criteria to become effective and competitive therapies for PD. These criteria include reproducibly producing sufficient numbers of cells with an authentic substantia nigra dopamine neuron A9 phenotype, which can integrate into the host brain after transplantation and form synapses (considered crucial for long-term functional benefits). Furthermore, it is essential that transplanted cells exhibit no, or only very low levels of, proliferation without tumor formation at the site of grafting. Cumulative research has shown that stem cell-based approaches continue to have great potential in PD, but key questions remain to be answered. Here, we review the most recent progress in research on stem cell-based dopamine neuron replacement therapy for PD and briefly discuss what the immediate future might hold. © 2021 International Parkinson and Movement Disorder Society     

Dopamine Transporter Availability in Early Parkinson's Disease is Dependent on Sunlight Exposure

Background

Preliminary studies suggested seasonality of dopaminergic functioning, but it is unknown whether dopamine transporter (DAT) expression in humans is also dependent on the seasons. We, therefore, investigated seasonal and sunlight-dependent effects on DAT availability in early Parkinson's disease (PD) patients and healthy controls.

Methods

DAT single-photon emission computed tomography scans (n = 730) were gathered from the Parkinson's Progression Marker Initiative (PPMI) database. We used global horizontal irradiance (GHI) as proxy for sun exposure/month and assessed associations between striatal DAT availability and season (autumn/winter versus spring/summer), GHI and latitude of the PPMI site.

Results

In PD patients, DAT availability in the left caudate nucleus was higher in spring/summer (B [standard error (SE)] = 0.05 [0.02], P = 0.03) and positively associated with higher sun exposure (B [SE] = 0.59 [0.22] × 10⁻³, P = 0.007). Latitude (in degrees north) of the PPMI site was negatively associated with DAT availability in both PD and healthy controls.

Conclusion

Striatal DAT availability may be influenced by daylight exposure. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.     

Cognitive Impairment in Parkinson's Disease without Dementia: Subtypes and Influences of Age

Background and Purpose

Cognitive impairments are common in Parkinson''s disease (PD), although the severity of these impairments does not significantly impair the patient''s daily activities. The aim of this study was to determine the frequency of mild cognitive impairment (MCI) of Parkinson''s disease (PDMCI) and its subtypes in nondemented PD patients. We also evaluated the influence of age on the pattern of subtypes of PDMCI.

Methods

A total of 141 consecutive, nondemented PD patients underwent a comprehensive neuropsychological assessment covering the five cognitive domains: attention, language, visuospatial, memory, and executive functions. PDMCI was defined as impaired performance in at least one of these five cognitive domains. The influence of age on the distribution of subtypes of PDMCI was assessed by comparing patients in two groups dichotomized according to their age at assessment (younger vs. older).

Results

Fifty-seven (40.4%) of the nondemented PD patients had an impairment in at least one domain, and were therefore considered as having PDMCI. The age at assessment and age at disease onset were significantly higher in the PDMCI patients. The amnestic type of PDMCI was the most frequent, followed by the visuospatial, linguistic, executive, and attention types in that order. The frequency of PDMCI was higher for all subtypes in the older group; the domain that was influenced the most by age was executive function.

Conclusions

MCI was common in PD and the subtypes were diverse. Age was found to be an important risk factor for the development of PDMCI, particularly for the executive subtype. These results indicate that the concept of MCI should be introduced in PD.     

Protective Effects of Physical Exercise in Alzheimer's Disease and Parkinson's Disease: A Narrative Review

Alzheimer''s disease (AD) and Parkinson''s disease (PD) are devastating, frequent, and still incurable neurodegenerative diseases that manifest as cognitive and motor disorders. Epidemiological data support an inverse relationship between the amount of physical activity (PA) undertaken and the risk of developing these two diseases. Beyond this preventive role, exercise may also slow down their progression. Several mechanisms have been suggested for explaining the benefits of PA in the prevention of AD. Aerobic physical exercise (PE) activates the release of neurotrophic factors and promotes angiogenesis, thereby facilitating neurogenesis and synaptogenesis, which in turn improve memory and cognitive functions. Research has shown that the neuroprotective mechanisms induced by PE are linked to an increased production of superoxide dismutase, endothelial nitric oxide synthase, brain-derived neurotrophic factor, nerve growth factor, insulin-like growth factor, and vascular endothelial growth factor, and a reduction in the production of free radicals in brain areas such as the hippocampus, which is particularly involved in memory. Other mechanisms have also been reported in the prevention of PD. Exercise limits the alteration in dopaminergic neurons in the substantia nigra and contributes to optimal functioning of the basal ganglia involved in motor commands and control by adaptive mechanisms involving dopamine and glutamate neurotransmission. AD and PD are expansive throughout our ageing society, and so even a small impact of nonpharmacological interventions, such as PA and exercise, may have a major impact on public health.