Types of Dementia

Alzheimer’s disease (AD) is responsible for most cases of dementia and is the most studied type. Generally, one distinguishing feature of Alzheimer’s disease is memory difficulties. In an early stage, the person forgets small details of events, and later, entire experiences. Spatial orientation is also often affected in the early stages. As the disease progresses, language, planning and visuospatial skills are also affected.

If it occurs before the age of 65, it is more likely to be hereditary, representing around 1% of cases. The vast majority of cases occur in people over the age of 65, where the genetic component has little influence, although the risk increases if there is a first-degree relative with the disease.

The term vascular dementia refers to a group of dementias resulting from lesions caused by changes in blood flow in the brain.

The signs and symptoms of people with vascular dementia vary depending on the nature and location of the lesions in the brain, as well as other associated clinical conditions. In general, it results from a stroke in a large blood vessel or from microvascular disease.

Symptoms include a decline in complex attention, meaning the ability to pay attention to several stimuli at the same time, information processing speed and executive function, which involves planning, decision-making and judgement. As a result, the person may have more difficulty carrying out several tasks at the same time, responding to requests in good time and planning daily activities.

The progression of vascular dementia often occurs “in steps”, with periods of relative stability followed by sudden worsening due to new vascular events.

In this type of dementia, prevention and control of cardiovascular risk factors are essential.

Frontotemporal dementia usually has an earlier onset and a greater influence from genetic factors. Two main variants can be distinguished, and in both, memory and the ability to understand spatial relationships are generally preserved.

Behavioural variant

This is characterised by early changes in personality and social behaviour, including disinhibition, repetitive or compulsive behaviours, apathy, loss of empathy and socially inappropriate attitudes.

Language variant

Also known as Primary Progressive Aphasia (PPA), this variant is marked by the progressive loss of language, with relative preservation of other cognitive functions in the early stages. It affects the production and understanding of speech, which appears as difficulty finding and understanding words, naming objects and using grammar correctly. As a result, the person faces significant challenges in communication and social interactions.

Lewy body dementia is caused by the abnormal accumulation of protein deposits in the brain, known as Lewy bodies, and is more common in men.

It is characterised by marked fluctuations in cognitive state, especially in attention and alertness, with periods of greater clarity alternating with moments of confusion.

Complex visual hallucinations are common, as well as sleep disturbances and motor symptoms similar to those of Parkinson’s disease, such as muscle rigidity, resting tremor and slow, shuffling gait.

This type of dementia requires particular attention to medication, as some people are more sensitive to the side effects of antipsychotic medication, meaning its use must be carefully assessed.