Types of dementia

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Dementias are neurodegenerative disorders characterised by a progressive decline in cognitive functions and daily skills. To understand the complexity of these disorders, it is useful to divide them into macro-categories, reflecting on the different causes and manifestations of the various types of dementia.

In general, dementia can be grouped into 3 macro-categories:

1). Primary dementias, such as Alzheimer’s, Lewy body dementia and frontotemporal dementia, are characterised by direct damage to brain tissue;

2). Vascular dementias which are the result of circulatory problems that damage blood vessels in the brain;

3). Less common forms of dementia, such as inclusion body dementia and HIV-associated dementia, are characterised by unique and rare clinical and pathogenetic presentations, making them challenging in both diagnosis and treatment.

Understanding these macro-categories is essential for correct patient management.

Primary dementias

Primary dementias represent the majority of dementia cases and present distinctive symptoms and characteristics, due to direct damage to brain tissue.

Alzheimer’s Disease is the most common form of dementia, accounting for approximately 60-70% of all cases. It is mainly characterised by progressive memory loss, difficulty in organising thoughts, and problems with language and cognitive abilities. Brain changes include the formation of amyloid plaques and tau protein tangles.

Lewy Body Dementia is characterised by the presence of abnormal aggregates of proteins called Lewy bodies. Symptoms may include hallucinations, sleep disturbances, muscle stiffness, and changes in cognition. This form of dementia can also have symptoms similar to those of Parkinson’s Disease.

Frontotemporal dementia causes damage primarily to the frontal areas of the brain, responsible for controlling emotions and behaviour. Symptoms may include changes in personality, and communication skills, as well as impairments in executive functions, such as planning and impulse control.

Vascular dementias

Vascular Dementias are caused by circulatory problems that damage blood vessels in the brain, leading to symptoms similar to those of Primary Dementias but with distinctive features related to vascular insufficiency.

Within the vascular dementias, there are several subtypes based on the location and severity of brain damage. These subtypes may present specific symptoms and require differentiated management approaches.

Vascular Dementia is the second most common form of dementia after Alzheimer’s. It develops following a stroke or reduced blood circulation in the brain, causing damage to brain matter and resulting in cognitive deficits that can vary depending on the areas affected.

There are several risk factors for developing vascular dementia, including hypertension, diabetes, obesity, and smoking. Effective management of these risk factors can help prevent or delay the development of vascular dementia.

Less common forms

Less common forms of dementia represent an additional diagnostic and management challenge, as they are less typical and may present specific traits. This category includes dementia from specific neurodegenerative diseases and rare genetic conditions.

Inclusion-Body Dementia is characterised by the presence of abnormal protein aggregates within brain cells. This form of dementia can present motor and cognitive, as well as behavioural and psychiatric symptoms. The course of this form of dementia is often progressive over time.

Lastly, HIV-Associated Dementia can occur in the advanced stages of HIV infection due to the direct impact of the virus on the Central Nervous System (CNS). Symptoms may include cognitive and motor impairments that significantly affect the patient’s quality of life.

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