Role Of Hypertension In Binswanger Disease

Binswanger disease

Subcortical vascular dementia, previously known as Binswanger’s disease, is a progressive form of cerebral small vessel disease (SVD), another common form of dementia. SVD mainly affects the white matter and other subcortical structures of the brain. Patients can have different degrees of cognitive impairments; the main clinical features would include a past episode of “mini-strokes” or transient ischemic attacks that occurred. Physical examinations reveal upper motor signs, asymmetric hyperreflexia, and mild parkinsonism. Hypertension is another clinical feature, along with functioning and processing speed, which are the most commonly affected cognitive functions.¹

The causes of Binswanger disease are atherosclerosis, thromboembolism, and other conditions that obstruct blood vessels, with the common risk factors for atherosclerosis being risk factors for Binswanger’s disease like hypertension, smoking, hypercholesterolemia, heart disease, and diabetes mellitus.¹

Diagnosis

Imaging is normally recommended, such as brain MRIs for the diagnosis of Binswanger’s disease. Those protocols include FLAIR T2, echo gradient, susceptibility-weighted imaging for detecting blood products, and MR angiograms. The pathology of Binswanger's disease is the degeneration of white matter in the brain, which consists of a large number of nerves for communication.¹ 

Hypertension

Hypertension is when the pressure in your blood vessels is too high, characterised by 140 mmHg/90 mmHg or higher. An estimated 1.28 billion adults aged 30-79 years are affected by hypertension, most would be affected in low- and middle-income countries.

Risk factors of high blood pressure include:

• Old age
• Genetics
• Overweight or obesity
• Lack of physical activity
• High-salt diet
• Excess alcohol consumption

The impact of hypertension on most people has no symptoms, but people with very high blood pressure can experience symptoms, which include:

• Severe headaches
• Chest pain
• Dizziness
• Nausea
• Vomiting
• Anxiety
• Difficulty breathing
• Abnormal heart rhythms

Role of hypertension on Binswanger disease

As mentioned before, Binswange’s disease is the formation of ischemic lesions in the brain causing white matter degeneration. This can be caused by an increase in resistance to blood flow, causing low blood flow, and the dysfunction of the endothelium and blood-brain barrier (BBB).² 

Endothelial dysfunction is the first step to atherosclerosis, which is when the arteries become narrowed, it causes the activation of the inflammatory response, which in turn can lead to low-density lipoproteins (LDL) cholesterol getting deposited within the arterial wall, which slowly reduces the diameter of the blood vessel, reducing blood flow, increasing blood pressure, and ultimately causing hypertension. Hypertension can further exacerbate atherosclerosis by inducing hypertrophy on the arterial wall, decreasing the efficiency of oxygen transport within the arteries.²

Studies linking hypertension and Binswanger disease

Studies have shown that hypertension or cardiovascular diseases related to hypertension have been linked with the diagnosis of Binswanger’s disease in patients. Different studies have studied the association between cardiovascular diseases, such as hypertension, with Binswager’s disease and white matter degeneration.^3,4

For example, a study of 104 participants, included 44 patients with Binswanger’s disease, 30 patients with Alzheimer’s disease, and 30 healthy people. Researchers found that among the vascular risk factors associated with vascular dementia diseases, there was a significantly higher stroke history and hypertension incidences in patients with Binswanger’s disease compared to those with Alzheimer’s disease and the healthy control groups. They further concluded that patients with Binswanger had a significantly higher number of arteries with plaque in comparison with healthy persons.⁵

Moreover, Skoog et al. (1994) found that atherosclerosis is highly associated with subcortical vascular dementia. A different study done by the same author also found that chronic hypertension has been associated with the clinical presentation of periventricular and deep white matter alterations in the MRI. Fazekas et al. 1993, and Pantoni & Garcia, 1997, also found that the lumen of small arterioles is due to the buildup of hyaline materials. These changes were also reported by other researchers studying Binswanger’s disease.⁴

Treatment of Binswanger disease

The treatment options for this condition are relatively unknown, as despite a few studies that have included Binswanger’s disease patients, there hasn’t been a specific targeted treatment trial done. So currently, treatments are aimed at preventing the formation of Binswanger’s disease in patients.

Reduction in blood pressure

Since hypertension has been identified as a main risk factor for Binswanger’s disease, current treatment regimes are included to reduce the risk of strokes.⁶ Lacunar strokes can also be prevented by controlling a patient’s blood pressure. Increasingly more research has shown that a reduction of systolic blood pressure of 130 is much more effective than a range of 140-130 for stroke prevention.⁷ Also, blood pressure control has been shown to reduce the progression of cognitive decline associated with stroke.⁸

Antiplatelet therapy

The use of antiplatelet therapy is usually recommended when a patient has a form of lacunar stroke. However, the research evidence for its use is controversial, as there’s scarce evidence of the use of antiplatelet therapy for patients with Binswanger’s disease, and since Binswanger’s disease has a high risk of intracranial haemorrhage (ICH), the benefits vs. the risks are unknown unless further research is done.⁶

Physical activity

Physical activity has been shown to prevent cognitive impairment in normal ageing in healthy patients and reduce the speed of cognitive decline in people with mild cognitive impairment.⁹ The benefits of exercise and physical activity for stroke prevention and hypertension are also well researched, as they provide a lot of benefits like a reduction in blood pressure, anti-inflammatory effects, and an increase in oxygen capacity.⁶

Diet

High-salt diet raises blood pressure and increases the risk of stroke. A study found that it is also linked to an increase in oxidative stress, and a lowering of vascular resistance.¹⁰ Patients who suffer from strokes are recommended, by the American Heart Association, to consume only 1.5 mg of sodium per day.⁶

Summary

Binswanger’s disease is a neurological disorder caused by a reduction of blood flow, and the dysfunction of the blood-brain barrier, due to the formation of atherosclerosis which leads to hypertension and an increase in blood pressure. This increase in blood pressure can cause a low blood flow in the brain leading to lesions forming around the white matter regions and their degeneration. Treatments are mostly preventive measures that aim to reduce the development of hypertension or other vascular diseases like atherosclerosis, and hypercholesterolemia.