Overview

Your brain is an indispensable organ that controls different parts of the body. As complex as the brain is, it is also extremely delicate. This is because slight changes or impaired ability of the nerve cells in your brain to effectively communicate with each other can lead to brain disorders. Some of these disorders can be progressive and worsen over time. However, dementia, which is one of these brain disorders, affects the quality of life, which could be coupled with life-threatening complications.

Dementia is an umbrella term that encompasses a set of symptoms that affect your memory, thinking, reasoning, personality, and behaviour. Dementia comes in different forms with varying symptoms, which will determine strategies for the management of people living with the condition. Thus, in this article, you will understand the meaning, causes, and differences between mixed dementia and vascular dementia.

Meaning of mixed dementia

Mixed dementia (MD) as the name implies, results from a combination of two or more types of dementia. The most common types of mixed dementia are Alzheimer’s disease (AD) and Vascular dementia (VaD). It occurs as a result of cognitive decline sufficient to cause an impaired ability to perform daily activities due to the coexistence of Alzheimer’s disease and cerebrovascular involvement diagnosed by the appearance of certain clinical criteria.¹

According to The International Classification of Diseases and Health Related Problems (ICD-10), the term MD is used for patients who meet the criteria for vascular dementia and Alzheimer’s disease. Hence, the clinical features of MD include:²

• Higher occurrence of depression
• Gait disorder
• Presence of ischemic lesions
• Presence of a second systemic or brain disorder
  

In countries where vascular risk factors are more common, there tends to be an increased incidence of cerebral ischemic lesions. Nevertheless, the diagnosis of MD is conducted separately based on the identification of vascular and ischemic lesions. The occurrence of AD pathology results in higher rates of MD.^3,4

Risk factors of mixed dementia

The symptoms associated with mixed dementia can vary as this depends on the area of the brain impacted. However, hypertension is one of the well-known risk factors for the development of AD and VaD simultaneously. There is an association between AD and vascular risk factors associated with the development of VaD such as smoking, diabetes mellitus, history of cardiovascular disease and atrial fibrillation. Other risk factors of MD include:³

• People assigned male at birth (AMAB)
• Older age
• Exposure to anaesthesia in older adults

Definition of vascular dementia

Vascular dementia (VaD) is a condition that occurs when the blood vessels that supply the brain (i.e. the arteries) are damaged. Your blood transports oxygen and nutrients to the brain for optimal functioning. However, reduced blood flow to the brain cells occurs when these blood vessels become damaged. The damage to the blood vessels could be triggered by diseases such as atherosclerosis and other cerebrovascular diseases.⁵  

According to Alzheimer’s Research UK, there are different causes and types of vascular dementia. This depends on how the blood vessels are damaged which occurs progressively. Occasionally, a person can have more than one cause of vascular dementia. VaD can affect people of all ages but this condition is more prevalent in older adults between the ages of 80-88.⁴ 

Different types of vascular dementia 

Small vessel dementia 

Small vessel dementia results from damage to the small arteries that supply the brain. These small arteries only supply a small part of the brain, so damage to the arteries might not be noticed until it becomes severe. This type of dementia shows gradual progression in disease severity and is linked to hypertension, heart valve diseases and stroke.⁶ 

Multi-infarct dementia 

Multi-infarct dementia is caused by a series of small strokes that occur in the part of the brain called infarcts. Thus, if someone has several small strokes at different times, multiple infarcts can build up in their brain. It is usually diagnosed when numerous micro-haemorrhages are seen in the brain during a scan.⁷ 

Hereditary vascular dementia 

This type of VaD is inherited in an autosomal dominant pattern. One of its distinguishing features is its early onset, typically between 20 and 40 years of age. The patient presents with symptoms of depression, migraine and the presence of white matter lesions and multiple lacunes.⁸

Risk factors and symptoms of vascular dementia

Risk factors of VaD can be categorised into modifiable and non-modifiable risk factors.

Modifiable risk factors 

These include:⁶ 

• Uncontrolled diabetes mellitus
• Sedentary lifestyle
• Cardiovascular problems
• Obesity
• Metabolic syndrome
• Smoking
• Alcohol abuse

Lifestyle modification and management of these conditions can reduce the severity of symptoms and risk of developing VaD. 

Non-modifiable risk factors 

These include:⁶ 

• Old age 
• Genetic mutation
• Post-menopausal
• Lower socioeconomic status
• Previous history of heart problems

Symptoms of Vascular Dementia

The symptoms associated with vascular dementia include: ⁶

• Problems with planning, organising and making decisions
• Concentration problems and feelings of confusion
• Increasing cognitive difficulties in performing tasks like reading, driving and learning a new language
• Personality changes such as low motivation, high sensitivity and apathy 

Key differences between mixed dementia and vascular dementia

The symptoms of MD may be similar to those of VaD but there are some key differences between the two which include: 

Management and treatment of mixed dementia and vascular dementia

Control of cardiovascular disease risk factors especially hypertension and hyperlipidemia and other strategies to prevent recurrent stroke help to slow the progression of mixed dementia. The use of cholinesterase inhibitors such as galantamine and rivastigmine shows positive effects on cognitive and functional outcomes in people with MD.  Also, statin therapy can reduce the incidence and progression of MD and VaD. Appropriate diagnosis and treatment of atrial fibrillation and the use of anticoagulation for thromboembolic disease will reduce the occurrence and severity of VaD and MD.¹

Management of hypertension is one of the most recommended interventions for reducing the risk of stroke and subsequently, VaD. Lifestyle modification such as incorporation of regular exercise routine, cessation of smoking and alcohol intake will also prevent stroke and onset of VaD. Additionally, the use of donepezil and memantine provides synergistic effects in the treatment of individuals with VaD. Depression associated with VaD can be treated with selective serotonin reuptake inhibitors (SSRIs) or other antidepressants.¹

Diagnosis of mixed dementia and vascular dementia

According to the Alzheimer’s Disease Diagnostic and Treatment Centers (ADDTC), the criteria for diagnosis of MD include the following clinical features:¹⁰

• Cognitive decline and loss of cognitive function in other areas
• Cerebral vascular injury (CVI)
• Detection of white matter lesions in brain images
• The onset of dementia three months after the patient had a cerebral stroke 

However, MD is usually diagnosed based on autopsy results. Neuroimaging techniques such as computed tomography (CT) scan, magnetic resonance imaging (MRI), and positron emission tomography (PET) can be used to increase diagnostic certainty and detect strokes, tumours and other problems that cause dementia.

According to the Alzheimer’s Society UK, there is no single confirmatory test for vascular dementia. A medical professional needs to make a differential diagnosis to rule out conditions with similar symptoms. All this will enable the doctor to make an accurate diagnosis of VaD. 

Summary

Mixed dementia (MD) and vascular dementia (VaD) are neurodegenerative diseases that are frequently associated with older adults. MD occurs when an Alzheimer’s disease patient also has a neurological disorder which could be VaD, cerebrovascular disease, or Lewy body disease. VaD results from damage to the blood vessels that supply specific areas of the brain. Both MD and VaD share similar symptoms but have key differences as well in terms of pathogenesis, age clinical presentation, etc. Control of risk factors leading to cardiovascular diseases and lifestyle modification are interventions for the control of MD and VaD. This is coupled with the use of cholinesterase inhibitors and SSRIs depending on the severity of symptoms and presence of psychiatric complications. 

FAQs

What is the main risk factor for Vascular Dementia?

Hypertension is the primary factor that can increase a person’s risk of developing vascular dementia. 

What is the most common sign seen in Vascular Dementia?

The most common signs seen in the early stages of vascular dementia include difficulty planning and organising, solving problems, performing tasks and making decisions.  

Is there a cure for Mixed Dementia?

There is no cure for any form of dementia, including mixed dementia. Treatment and management strategies are aimed at slowing the progression of disease, enhancing cognitive function and improving the quality of life.