Effect of cerebral small vessel disease on cognitive impairment in Parkinson’s disease: a systematic review and meta-analysis
Original Article

Effect of cerebral small vessel disease on cognitive impairment in Parkinson’s disease: a systematic review and meta-analysis

Huijuan Wan1,2,3#, Guangyao Wang4#, Qi Liu3, Yilong Wang1,2,5,6,7

1Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China; 2China National Clinical Research Center for Neurological Diseases, Beijing, China; 3Department of Neurology, First Affiliated Hospital, Xiamen University, School of Medicine, Xiamen University, Xiamen, China; 4Department of Neurology, Beijing Jishuitan Hospital, Beijing, China; 5Chinese Institute for Brain Research, Beijing, China; 6Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China; 7Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease, Beijing, China

Contributions: (I) Conception and design: Y Wang; (II) Administrative support: Y Wang; (III) Provision of study materials or patients: H Wan, G Wang; (IV) Collection and assembly of data: H Wan, G Wang; (V) Data analysis and interpretation: H Wan; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

#These authors contributed equally to this work and should be considered as co-first authors.

Correspondence to: Yilong Wang. Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China; China National Clinical Research Center for Neurological Diseases, Beijing, China; Chinese Institute for Brain Research, Beijing, China; Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease, Beijing, China; No. 119 South 4th Ring West Road, Fengtai District, Beijing 100070, China. Email: yilong528@aliyun.com.

Background: The occurrence of various cerebrovascular diseases can easily induce cognitive impairment in the elderly. Therefore, it is of great clinical significance to correctly understand the relationship between these key pathogenic factors and cognitive impairment of Parkinson’s disease. To explore the effect of cerebrovascular disease on cognitive impairment in Parkinson’s disease by meta-analysis.

Methods: PubMed, Medline, Embase, and Web of Science databases were selected as the sources for the literature search. English language articles were included. Literature related to this study were published from January 2001 to January 2021. Literature was screened and the quality was evaluated. RevMan 5.3 software was used to perform the meta-analysis on the effects of cerebrovascular disease on cognitive impairment in Parkinson’s disease.

Results: Six articles were finally included, involving a total of 5,552 cases. Of these, 2,684 were positive cases, accounting for 48.3%. Compared with patients with non-Parkinson’s cognitive impairment, patients with cognitive impairment in Parkinson’s disease caused by cerebral small vessel disease had significant differences in executive ability (OR =1.62, 95% CI: 1.21–2.16, P=0.001), memory (OR =1.48, 95% CI: 1.30–1.68, P<0.00001), information processing (OR =0.60, 95% CI: 0.35–1.03, P=0.07), language communication (OR= 4.72, 95% CI: 3.26–6.85, P<0.00001), and overall cognitive function (OR =0.72, 95% CI: 0.52–0.99, P=0.05).

Conclusions: A total of 6 studies were included in this meta-analysis on the influence of cerebral small vessel disease on cognitive impairment in Parkinson’s disease. This study shows that cerebrovascular disease has different effects on all aspects of cognitive function of Parkinson’s disease.

Keywords: Cerebral small vessel disease; cognitive impairment; Parkinson’s disease; meta-analysis

Submitted Nov 30, 2021. Accepted for publication Mar 04, 2022.

doi: 10.21037/atm-22-276

Introduction

With the advent of the aging population, the probability of people suffering from various chronic diseases is also increasing. Among them, the number of clinical cases of Alzheimer’s disease, behavioral disorders, and cognitive impairment caused by Parkinson’s disease is also increasing year by year (1,2). Cognitive impairment not only poses a huge psychological and physiological burden to patients, but also greatly reduces their quality of life. According to the clinical research results, there are many specific pathogenic factors of cognitive impairment in Parkinson’s disease, such as age, disease history, drug history and lifestyle, and there is no unified conclusion (3-5). However, Among these pathogenic factors, cerebral small vessel diseases (6-8), including lacunar cerebral infarction, white matter injury or looseness, cerebral cortex atrophy, cerebral microvascular rupture and enlarged perivascular space, may cause cognitive impairment of Parkinson’s disease in elderly patients (see Figure 1). At the same time，the he number and location of small cerebrovascular diseases in the basal ganglia may independently lead to gait/posture dysfunction in Parkinson disease patients (9). The effect of small cerebral vessels on Parkinson’s cognitive impairment is still in the exploratory stage. Therefore, it is of great clinical significance to understand the relationship between these key pathogenic factors and cognitive impairment in Parkinson’s disease, this is the innovation and significance of this work. In this study, meta-analysis was used to further explore the effect of small vessel disease on cognitive impairment in Parkinson’s disease. We present the following article in accordance with the MOOSE reporting checklist (available at https://atm.amegroups.com/article/view/10.21037/atm-22-276/rc).

Figure 1 The possible effects of cerebral small vessel disease on cognitive impairment in Parkinson’s disease.

Methods

Data sources and search strategy

PubMed, Medline, Embase, and Web of Science literature databases were used in this study. When conducting literature retrieval, the language of publications was limited to English, and the publication time was limited from 2001 to 2021. The literature retrieval methods involved rapid retrieval of English words and combinatorial retrieval of literature keywords. The search keywords were “cerebrovascular disease”, “Parkinson’s disease”, “effect”, and “cognitive impairment”. The full-text searches of the database were carried out through free combinations of these keywords. At the same time, the relevant citations were tracked by manual retrieval. The retrieval time was October 21, 2021.

Inclusion criteria

The inclusion criteria were as follows: (I) the included studies were case-control studies on the correlation between cerebrovascular diseases and cognitive function in Parkinson’s disease; (II) data related to the evaluation of cognitive impairment was complete.

Exclusion criteria

The exclusion criteria were as follows: (I) the subjects were patients with acute stroke or dementia; (II) subjects were complicated with infection, epilepsy, tumor, multiple sclerosis, or psychosis, which could potentially affect cognitive function; (III) incomplete data or logical error; (IV) only no repeatedly published data was used as a reference.

Selection of literature

Literature was screened by 2 independent researchers. All titles were first read and compared by these 2 researchers. Then, ineligible publications were excluded, while eligible publications were obtained and fully read by these 2 researchers. The 2 researchers performed cross-checking to exclude uncertain papers. Finally, a third person was introduced to assist in arbitration.

Data extraction

Two researchers independently extracted the relevant data and information for this study, including the first author, the time of publication, the number of patients with cerebrovascular diseases and controls, the average age and sex ratio of the subjects. All data in this study were extracted and analyzed independently by 2 authors. In case of divergent opinions, a comprehensive evaluation was conducted by a third party.

Literature quality assessment

The Newcastle Ottawa Scale (NOS) was used to evaluate the quality of the included studies. NOS is a commonly used quality evaluation in case-control studies and cohort studies. It should be noted that NOS is a continuous cooperation project. The purpose of this project is to provide a simple and convenient quality assessment tool for the inclusion of non-randomized studies in the systematic review. the score of the scale, and the full score is 9 points. The evaluation items mainly include three items: object selection, comparability, outcome (cohort study) or exposure (case-control). There are evaluation items under each item, and each item is represented by scores when appropriate. The highest score of comparability is 2 points. At present, NOS scale has been widely used to evaluate case-control studies and cohort studies. Five articles scored 6, 1 article scored 7, and 1 article scored 5, indicating good quality. The higher the score, the better the literature quality and the lower the bias.

Statistical analysis

Meta-analysis was conducted using RevMan 5.3 software provided by the Cochrane Collaboration Network. Heterogeneity was tested by the Q test, where P>0.1 and I2<50% indicated that the homogeneity among the studies was good, and the fixed effect model was used. When P≤0.1 or I2≥50%, the heterogeneity among the groups was large, and the random effect model was used. If the heterogeneity was too large, subgroup analysis was carried out (P>0.1 and I2<50%). P<0.1 was considered statistically significant for all the above effect analyses.

Results

Literature search and screening results

In this study, 615 relevant publications were initially found. First, records removed before screening: duplicate records removed (n=132), records marked as ineligible by automation tools (n=87), records removed for other reasons (n=34). Then 335 articles were filtered out by records screen the remaining 27 articles were included in the primary screening, and finally 6 studies were included involving a total of 5,552 cases (Figure 2). Of these cases, 2,684 were positive cases, accounting for 48.3%. The basic characteristics of the studies are shown in Table 1, while the reasons for literature exclusion are shown in Table 2.

Figure 2 Search and selection flow chart of literature.

Table 1

Summary of the basic characteristics of the studies and areas of cognitive impairment affected

Serial number   Author     Study location Year of publication Total cases Impact indicators Quality score (points)
1   Malek N et al. (5)     Glasgow, Kingdom 2016 1759 (I)(II)(III)(V) 4
2   Reed BR et al. (10)     Martinez 2004 62 (I)(II)(III)(V) 4
3   Theilmann RJ et al. (11)     San Diego, USA 2013 51 (I)(II)(IV)(V)(VI) (VII)(VIII)(IX) 8
4   Poels MM et al. (12)     Rotterdam 2012 3979 (I)(II)(IV) 3
5   Yakushiji Y et al. (13)     Saga, Japan 2008 518 (I)(II)(IV) 3
6   MacLullich AM et al. (14)     France 2004 100 (V) 1

(I) executive ability; (II) memory; (III) information processing; (IV) language communication; (V) overall cognitive function; (VI) learning ability; (VII) visual space perception; (VIII) attention; (IX) language fluency.

Table 2

Excluded literature and reasons for exclusion (not all)

Serial number Author Year of publication Reason for exclusion
1 Rensma SP et al. (15) 2018 Not enough data
2 Wan Y et al. (16) 2019 Not enough data
3 Foo H et al. (17) 2016 No group comparison data
4 Ma X et al. (18) 2021 Not enough data

Literature quality evaluation

According to our retrieval strategy, literature retrieval was implemented, and finally 6 studies were included in this meta-analysis. A total of 5,552 patients were included in these 6 studies. Among them, patients with cerebrovascular diseases were included in the study group and were compared to patients in the control group. The basic characteristics and NOS scores of the included studies are shown in Table 1.

Meta-analysis results

Executive ability

Five studies (5,10-13) reported the effects of cerebrovascular diseases on the executive ability of patients with cognitive impairment in Parkinson’s disease, including 3,085 patients with executive dysfunction in Parkinson’s disease and 2,367 patients with executive dysfunction in non-Parkinson’s disease. There was no heterogeneity between the studies (I2=46%, P=0.12). Fixed effect model analysis showed that compared with the executive dysfunction of patients with non-Parkinson’s disease, the executive ability was a significant difference in patients with Parkinson’s disease and executive dysfunction caused by cerebral small vessel disease (OR =1.62, 95% CI: 1.21–2.16, P=0.001), as shown in Figure 3.

Figure 3 Effect of cerebrovascular disease on executive ability in Parkinson’s disease.

Memory

Five studies (5,10-13) reported the effects of cerebrovascular diseases on memory in Parkinson’s disease patients with cognitive impairment, including 2,980 patients with memory impairment in Parkinson’s disease and 2,193 patients with memory impairment in non-Parkinson’s disease. There was heterogeneity among the studies (I2=85%, P<0.0001). Random effect model analysis showed that compared with patients with memory impairment in non-Parkinson’s disease, there was a significant difference in patients with memory impairment in Parkinson’s disease caused by cerebral small vessel disease (OR =1.48, 95% CI: 1.30–1.68, P<0.00001), as shown in Figure 4.

Figure 4 Effect of cerebrovascular disease on memory in Parkinson’s disease.

Information processing

Two studies (5,10) reported the impact of cerebrovascular diseases on information processing in Parkinson’s disease, including 163 patients with information processing disorder in Parkinson’s disease and 120 patients with information processing disorder in non-Parkinson’s disease. There was no heterogeneity between the studies (I2=0%, P=0.36). Fixed effect model analysis showed that compared with non-Parkinson’s disease patients with information processing disorder, there was a significant difference in Parkinson’s disease patients with information processing disorder caused by cerebral small vessel disease (OR =0.60, 95% CI: 0.35–1.03, P=0.07), as shown in Figure 5.

Figure 5 Effect of cerebrovascular disease on information processing in Parkinson’s disease.

Language communication

Three studies (11-13) reported the effects of cerebrovascular diseases on language communication in Parkinson’s disease, including 1,152 patients with language communication disorder in Parkinson’s disease and 957 patients with language communication disorder in non-Parkinson’s disease. There was heterogeneity among the studies (I2=67%, P=0.05). Random effect model analysis showed that compared with non-Parkinson’s disease patients with language communication disorder, there was a significant difference in Parkinson’s disease patients with language communication disorder caused by cerebral small vessel disease (OR =4.72, 95% CI: 3.26–6.85, P<0.00001), as shown in Figure 6.

Figure 6 Effect of cerebrovascular disease on language communication in Parkinson’s disease.

Overall cognitive impairment

Four studies (5,10,11,14) reported the effect of cerebrovascular diseases on overall cognitive impairment in Parkinson’s disease, including 358 patients with overall cognitive impairment in Parkinson’s disease and 759 patients with overall cognitive impairment in non-Parkinson’s disease. There was heterogeneity among the studies (I2=76%, P=0.01). Random effect model analysis showed that compared with patients with overall cognitive impairment in non-Parkinson’s disease, patients with overall cognitive impairment in Parkinson’s disease caused by cerebral small vessel disease had a significant difference (OR =0.72, 95% CI: 0.52–0.99, P=0.05), as shown in Figure 7.

Figure 7 Effect of cerebrovascular disease on overall cognitive impairment in Parkinson’s disease.

Analysis of publication bias

Publication bias analysis was not performed as few articles were included in this study.

Discussion

Cognitive impairment is the most common non-motor symptom in Parkinson’s disease. It can be divided into mild cognitive impairment and dementia according to the severity of the disease. Mild cognitive impairment in Parkinson’s disease is a risk factor for the development of Parkinson’s dementia. At present, this type of cognitive impairment accounts for about 30% of patients with Parkinson’s disease cognitive impairment, and most of them are non-forgetting. The predominant clinical manifestations are reduced learning ability, memory function, and inattentiveness. At present, the pathogenesis of cognitive impairment in Parkinson’s disease is not clear, but most scholars generally believe that it is mainly related to brain beta amyloid protein deposition and microvascular disease caused by pathological mechanisms such as oxidative stress, brain mitochondrial function damage, and changes in various neurotransmitters in the nervous system (19). At the same time, according to the results of relevant clinical studies, baseline orthostatic hypotension and autonomic nerve dysfunction in patients with early Parkinson’s disease are related to the mediating effect of cerebrovascular disease and the decline of cognitive ability in the later stage (20-23).

The occurrence of cerebral small vessel disease is usually caused by 2 main factors, namely amyloidosis of cerebral white matter and hypertension (24). According to the research conclusions of Hachinski et al. (25) and other research groups, cerebral small vessel hemorrhage caused by cerebral white matter amyloidosis mainly forms blood foci in the cerebral lobes, while cerebral small vessel hemorrhage caused by hypertension mainly occurs in the deep part of the brain, such as the thalamus and basal ganglia. In addition, according to the meta-analysis results of Wu et al. (26), damage to the deep brain, lateral lobe, basal ganglia, and hypothalamus will affect the cognitive function of patients to varying degrees. In addition to cognitive function, there is a close relationship between cerebral small vessel diseases and motor symptoms. It is found by clinical research that the hyperintensity of deep white matter in the middle frontal lobe is a risk factor for postural instability and gait disorder, which supports the contribution of vascular pathology of Parkinson’s disease (16).

Cognitive impairment and dementia are recognized as the consequences of the neurodegenerative process of Parkinson’s disease. Patients will not only show abnormalities in executive function, memory, language, attention, visual space and other fields, but also affect their quality of life and prognosis to varying degrees. Although the research on phobia with cognitive impairment and cerebrovascular disease is gradually increasing, its pathological mechanism is not clear, and there are few clinical research reports on whether the intervention of cerebrovascular disease is conducive to improving the symptoms of Parkinson’s cognitive impairment and delaying the progress of the disease. Therefore, in the future, large-scale prospective studies and relevant basic experiments need to be improved to clarify the relationship and specific mechanism between cerebrovascular disease and Parkinson’s cognitive impairment, so as to provide clues and ideas for the diagnosis, treatment and prognosis of Parkinson’s patients (27,28).

In this study, the effects of cognitive impairment in Parkinson’s disease caused by cerebrovascular disease were analyzed by meta-analysis. Compared with patients with non-Parkinson’s disease, patients with Parkinson’s disease cognitive impairment caused by cerebral small vessel disease were significantly different in terms of executive ability, memory, information processing, language communication, and overall cognitive function (P<0.01). Therefore, these data show that cerebral small vessel disease has different effects on all aspects of cognitive function of Parkinson’s disease.

Conclusions

In conclusion, cognitive impairment is the main result of neurodegenerative diseases and the continuous progression of Parkinson’s disease. Because patients are significantly lower than healthy people in terms of executive ability, memory function, language expression, and attention and visual space perception, their quality of life is seriously affected. Although there are more and more reports on the impact of cerebrovascular disease on cognitive impairment in Parkinson’s disease, the research on its specific pathogenesis has not been systematic. Therefore, through the retrieval of relevant literature and meta-analysis of the existing research, we revealed the relationship between these conditions and the specific impact of cerebrovascular disease. These findings have guiding significance and clinical reference value for the diagnosis, treatment, and prognostic improvement of patients with Parkinson’s disease cognitive impairment.

Acknowledgments

Funding: This work was funded by The National Natural Science Foundation of China (No. 81825007); Beijing Outstanding Young Scientist Program (No. BJJWZYJH01201910025030); Youth Beijing Scholar Program (No. 010); Beijing Talent Project - Class A: Innovation and Development (No. 2018A12); “National Ten-Thousand Talent Plan”- Leadership of Scientific and Technological Innovation, and National Key R&D Program of China (Nos. 2017YFC1307900 and 2017YFC1307905).

Footnote

Reporting Checklist: The authors have completed the MOOSE reporting checklist. Available at https://atm.amegroups.com/article/view/10.21037/atm-22-276/rc

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://atm.amegroups.com/article/view/10.21037/atm-22-276/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

  1. Zesiewicz TA. Parkinson Disease. Continuum (Minneap Minn) 2019;25:896-918. [Crossref] [PubMed]
  2. Aarsland D, Brønnick K, Larsen JP, et al. Cognitive impairment in incident, untreated Parkinson disease: the Norwegian ParkWest study. Neurology 2009;72:1121-6. [Crossref] [PubMed]
  3. Baiano C, Barone P, Trojano L, et al. Prevalence and clinical aspects of mild cognitive impairment in Parkinson's disease: A meta-analysis. Mov Disord 2020;35:45-54. [Crossref] [PubMed]
  4. Rosano C, Metti AL, Rosso AL, et al. Influence of Striatal Dopamine, Cerebral Small Vessel Disease, and Other Risk Factors on Age-Related Parkinsonian Motor Signs. J Gerontol A Biol Sci Med Sci 2020;75:696-701. [Crossref] [PubMed]
  5. Malek N, Lawton MA, Swallow DM, et al. Vascular disease and vascular risk factors in relation to motor features and cognition in early Parkinson's disease. Mov Disord 2016;31:1518-26. [Crossref] [PubMed]
  6. Chen H, Wan H, Zhang M, et al. Cerebral small vessel disease may worsen motor function, cognition, and mood in Parkinson's disease. Parkinsonism Relat Disord 2021;83:86-92. [Crossref] [PubMed]
  7. Du J, Zhu H, Zhou J, et al. Structural Brain Network Disruption at Preclinical Stage of Cognitive Impairment Due to Cerebral Small Vessel Disease. Neuroscience 2020;449:99-115. [Crossref] [PubMed]
  8. Shibata K, Sugiura M, Nishimura Y, et al. The effect of small vessel disease on motor and cognitive function in Parkinson's disease. Clin Neurol Neurosurg 2019;182:58-62. [Crossref] [PubMed]
  9. Chen H, Zhang M, Liu G, et al. Effect of small vessel disease burden and lacunes on gait/posture impairment in Parkinson's disease. Neurol Sci 2020;41:3617-24. [Crossref] [PubMed]
  10. Reed BR, Eberling JL, Mungas D, et al. Effects of white matter lesions and lacunes on cortical function. Arch Neurol 2004;61:1545-50. [Crossref] [PubMed]
  11. Theilmann RJ, Reed JD, Song DD, et al. White-matter changes correlate with cognitive functioning in Parkinson's disease. Front Neurol 2013;4:37. [Crossref] [PubMed]
  12. Poels MM, Ikram MA, van der Lugt A, et al. Cerebral microbleeds are associated with worse cognitive function: the Rotterdam Scan Study. Neurology 2012;78:326-33. [Crossref] [PubMed]
  13. Yakushiji Y, Nishiyama M, Yakushiji S, et al. Brain microbleeds and global cognitive function in adults without neurological disorder. Stroke 2008;39:3323-8. [Crossref] [PubMed]
  14. Maclullich AM, Wardlaw JM, Ferguson KJ, et al. Enlarged perivascular spaces are associated with cognitive function in healthy elderly men. J Neurol Neurosurg Psychiatry 2004;75:1519-23. [Crossref] [PubMed]
  15. Rensma SP, van Sloten TT, Launer LJ, et al. Cerebral small vessel disease and risk of incident stroke, dementia and depression, and all-cause mortality: A systematic review and meta-analysis. Neurosci Biobehav Rev 2018;90:164-73. [Crossref] [PubMed]
  16. Wan Y, Hu W, Gan J, et al. Exploring the association between Cerebral small-vessel diseases and motor symptoms in Parkinson's disease. Brain Behav 2019;9:e01219. [Crossref] [PubMed]
  17. Foo H, Mak E, Yong TT, et al. Progression of small vessel disease correlates with cortical thinning in Parkinson's disease. Parkinsonism Relat Disord 2016;31:34-40. [Crossref] [PubMed]
  18. Ma X, Li S, Li C, et al. Total Cerebral Small Vessel Score Association With Hoehn and Yahr Stage in Parkinson's Disease. Front Aging Neurosci 2021;13:682776. [Crossref] [PubMed]
  19. Gutteridge DS, Saredakis D, Badcock NA, et al. Cerebrovascular function during cognition in Parkinson's disease: A functional transcranial Doppler sonography study. J Neurol Sci 2020;408:116578. [Crossref] [PubMed]
  20. Kario K, Eguchi K, Hoshide S, et al. U-curve relationship between orthostatic blood pressure change and silent cerebrovascular disease in elderly hypertensives: orthostatic hypertension as a new cardiovascular risk factor. J Am Coll Cardiol 2002;40:133-41. [Crossref] [PubMed]
  21. Fanciulli A, Leys F, Falup-Pecurariu C, et al. Management of Orthostatic Hypotension in Parkinson's Disease. J Parkinsons Dis 2020;10:S57-64. [Crossref] [PubMed]
  22. Al-Qudah ZA, Yacoub HA, Souayah N. Disorders of the Autonomic Nervous System after Hemispheric Cerebrovascular Disorders: An Update. J Vasc Interv Neurol 2015;8:43-52. [PubMed]
  23. Leclair-Visonneau L, Magy L, Volteau C, et al. Heterogeneous pattern of autonomic dysfunction in Parkinson's disease. J Neurol 2018;265:933-41. [Crossref] [PubMed]
  24. Cuadrado-Godia E, Dwivedi P, Sharma S, et al. Cerebral Small Vessel Disease: A Review Focusing on Pathophysiology, Biomarkers, and Machine Learning Strategies. J Stroke 2018;20:302-20. [Crossref] [PubMed]
  25. Hachinski V, Iadecola C, Petersen RC, et al. National Institute of Neurological Disorders and Stroke-Canadian Stroke Network vascular cognitive impairment harmonization standards. Stroke 2006;37:2220-41. [Crossref] [PubMed]
  26. Wu R, Feng C, Zhao Y, et al. A meta-analysis of association between cerebral microbleeds and cognitive impairment. Med Sci Monit 2014;20:2189-98. [Crossref] [PubMed]
  27. Smith CR, Cullen B, Sheridan MP, et al. Cognitive impairment in Parkinson's disease is multifactorial: A neuropsychological study. Acta Neurol Scand 2020;141:500-8. [Crossref] [PubMed]
  28. Kummer BR, Diaz I, Wu X, et al. Associations between cerebrovascular risk factors and parkinson disease. Ann Neurol 2019;86:572-81. [Crossref] [PubMed]

(English Language Editor: C. Betlazar-Maseh)

Cite this article as: Wan H, Wang G, Liu Q, Wang Y. Effect of cerebral small vessel disease on cognitive impairment in Parkinson’s disease: a systematic review and meta-analysis. Ann Transl Med 2022;10(6):288. doi: 10.21037/atm-22-276

Article Options

Download Citation

Share