A disorder related to tiny blood vessels in the brain, known as cortical small vessel disease, is directly linked to worsening motor function in Parkinson’s disease, according to a recent study.
An additional association between modifiable vascular risk factors, in particular hypertension, and dementia highlights the need to manage these risk factors in Parkinson’s patients.
The study, “Impact of small vessel disease on severity of motor and cognitive impairment in Parkinson’s disease,” was published in the Journal of Clinical Neuroscience.
Symptoms of Parkinson’s disease can be affected by different risk factors — any attribute, characteristic, or exposure of an individual that increases the likelihood of developing a disorder or injury. Notably, issues with the heart and its blood vessels, or cardiovascular risk factors, have been shown to contribute to greater motor dysfunction in Parkinson’s disease.
In addition, disorders rooted in the brain’s blood vessels, or cerebrovascular pathologies, are linked with an increased prevalence of parkinsonian symptoms, such as motor dysfunction, and cognitive impairment in the elderly.
The relationship among cortical small vessel disease — an umbrella term covering a variety of abnormalities related to small blood vessels in the brain — cognitive decline, and dementia is well-established. Despite this, small vessel disease is not considered a significant cause underlying cognitive impairment in Parkinson’s, and it is not clear whether and to what extent its symptoms and progression contribute to Parkinson’s motor severity and cognitive impairment.
Some of the most concrete evidence for understanding the impact of comorbidities — the simultaneous presence of two chronic diseases or conditions in a patient — in Parkinson’s and other neurodegenerative diseases has been obtained through autopsies of patients’ brains.
By comparing the clinical information collected from patients, such as motor function and cognitive ability, during treatment with an autopsy report, doctors can better assess the link among risk factors, the course of Parkinson’s disease, and the severity of parkinsonian symptoms and dementia.
Cerebrovascular disease pathologies, such as small vessel disease, have only been assessed in a limited number of autopsy studies of Parkinson’s patients.
Now, researchers at the University of Sydney Medical School in Australia have studied the relationship among vascular risk factors and small vessel disease and the severity of motor impairment, cognitive dysfunction, and dementia in Parkinson’s patients. Vascular risk factors studied included stroke, heart disease, hypertension, diabetes, and cigarette smoking.
To do so, they examined clinical information from 77 autopsy-confirmed Parkinson’s patients who were similar in age, cause of death, and duration or severity of Parkinson’s disease.
The researchers then examined clinical information collected during patient visits to determine the severity of cognitive dysfunction and motor impairment. The severity of motor impairment and disease progression was determined using the Hoehn and Yahr scale, while the Clinical Dementia Rating was used to assess the severity of cognitive dysfunction and progression.
Of the 77 patients, 65 percent had advanced-stage dementia. The mean duration of Parkinson’s disease was 12 years for patients with and without dementia. Patients with dementia had more vascular risk factors than those without dementia, including stroke, heart disease, hypertension and diabetes, and a longer history of cigarette smoking.
Researchers observed that the severity of small vessel disease was related to the degree of motor impairment. They did not find a link between the severity of small vessel disease and the presence of dementia in these patients.
They also found a link between the severity of modifiable vascular risk factors and cognitive impairment in the autopsies of Parkinson’s patients. Among the vascular risk factors, only hypertension was linked with cognitive impairment and dementia.
“Modifiable vascular risk factors relate most to the severity of cognitive rather than motor impairment in Parkinson’s disease,” the researchers wrote. This emphasizes the importance “of a holistic approach to the treatment of PD [Parkinson’s disease] including the potential for longterm cognitive benefits of early and aggressive management of vascular co-morbidities.”
“Our study suggests that neurologists treating patients with Parkinson’s disease should proactively manage their patient’s vascular risk factors, which may reduce gait and cognitive impairment, two of the main clinical features that undermine well-being and independence in patients with Parkinson’s disease,” lead study author Jillian Kril, PhD, said in a news article published in Neurology Today.