Types of Dementias: Characteristics and Symptoms
The different types of dementia are an acquired, chronic and generalized deterioration of cognitive functions. They affect two or more of the following areas: memory, ability to solve problems, the performance of perceptual-motor activities, the use of daily life skills, and emotional control.
The problem is caused by brain injuries, which don’t initially disturb the level of consciousness. The severity of the cognitive deficit in dementia interferes with the normal family, social and occupational functioning of the subject.
Characteristics of the different types of dementia
The different types of dementia have their own defining characteristics, namely:
- A global alteration of acquired cognitive abilities. For example, it causes impaired thinking, memory, reasoning, language, calculation, orientation, attention, etc.
- Cognitive decline is progressive. Increasingly, you can perceive a greater number of affected functions and a greater degree of deterioration.
- Memory loss is usually the most characteristic symptom, especially in the early stages.
- This is accompanied by aphasia, agnosia, or apraxia.
- The alteration of a specific mental function in isolation isn’t considered to be dementia.
- It’s chronic in nature, lasting more than 6 months.
- There’s no deterioration in the level of consciousness.
- It interferes with the person’s autonomy and quality of life.
- At first, the person is aware of their illness.
- It’s an irreversible process.
- It involves both hemispheres and large areas of the brain.
All sensory, cognitive, motor and behavioral functions can be affected in dementia. Alzheimer’s is the most frequent dementia, accounting for 75% of cases. Vascular dementia and Parkinson’s disease follow.
The increase in life expectancy means that these different types of dementia have become a public health problem, as more and more people reach old age. Neuropsychologists estimate that 25% of people over the age of 85 have some type of dementia.
Clinical manifestations of dementia
There are a number of symptoms common to all types of dementia. Depending on the capacity or ability affected, we’ll group them together to facilitate their understanding:
- Memory: Memory problems are often the first symptom of dementia. Recent memory is particularly affected and long-term memory and implicit memory are better preserved.
- Language: A marked impoverishment of language is observed, as well as a worsening in communicative initiative. In many cases, this can be mistaken for depression. However, linguistic incompetence is due to diffuse brain damage.
- The appearance of apraxias or inability to carry out previously learned skills. With dementia, apraxias usually occur in the final stages of the disease. This is why people forget how to dress, eat, groom themselves, etc.
- The presence of agnosia or the inability to recognize the stimuli that come through the senses. For example, they no longer recognize familiar faces (prosopagnosia), or are unable to position themselves in time and space (spatio-temporal agnosia).
- Calculus problems or acalculia.
- The alteration of executive functions: This manifests in the inability to plan or self-regulate their behavior according to where they are. There’s a failure to set goals and difficulty in thinking.
- Psychological disorders: The most frequent are hallucinations, paranoidism, tendency to flee and wander, mutism, pseudo-depression, passivity, self-centeredness, anxiety, and depression.
How to distinguish depression from dementia
In depressive disorders, there’s an apparent loss of intellectual functions – these have received the name pseudo-dementias. There’s often difficulty in the differential diagnosis between depression and dementia. In addition, some symptoms overlap between the two conditions:
| Depression | Dementia | |
| Start | Justified by past or present events. History of depression. | There’s no history to justify the onset of the disease. |
| Beginning and progression | Fast or acute. | Slow and insidious. |
| Duration | Less than 6 months. | More than 6 months. |
| Temporality | Depression is prior to cognitive and functional decline. | Cognitive and functional impairment precedes depression. |
| Disease awareness | There is consciousness. | There is no consciousness. |
| Culpability | They feel guilty and worry about their symptoms. | They blame others and don’t care about their symptoms. |
| Complaints | They do complain. | They don’t complain, or very rarely. |
| Cognitive impairment | General memory problems. | Recent memory deficits and manipulative fall. |
| Aphasias and agnosias | Non-existent. | Present. |
Types of dementias
Dementias can be classified according to the damage they cause or where this damage is. The most used classification is the location of the brain lesions, which allows them to be divided into cortical, subcortical, and axial dementias.
Cortical dementias
This type of dementia occurs, above all, due to lesions in the associative frontal and temporoparietooccipital areas. Generally, they’re manifested by neuropsychiatric disorders that begin with memory problems and, progressively, disorders such as aphasias, apraxias and agnosias appear. Also, psychological alterations may appear.
The final cognitive decline is devastating, although initially it can be hidden because the course is progressive and the symptoms appear slowly. Among these types of dementia, we find Alzheimer’s. It’s very common for the person not to be aware of their failings once the disease has progressed beyond its initial stages
Subcortical dementia
As its name suggests, in this type of dementia, the damage would occur below the cortex, or, more specifically, in structures such as the basal ganglia, the thalamus, or the brain stem. Initially, there would be no aphasic, apraxic or agnosic manifestations, but rather a lack of spontaneity and psychomotor and cognitive fluency. It’s accompanied by extrapyramidal disorders, such as tremors, dyskinesia, or akathisia.
Later, we find a frequent dulling and slowing down of cognitive processes. It’s also associated with mood-related problems, as well as the inability to carry out complex thoughts or tasks. These types of clinical manifestations are characteristic of dementia such as Parkinson’s.
Axial dementias
According to Portellano, these are caused by damage to structures located in the mid-axis of the brain, such as the hippocampus, hypothalamus, fornix or mammillary bodies. They cause loss of fixation memory, a loss of initiative, and a lack of concern for their surroundings.
The paradigm of axial dementias is Wernicke-Korsakoff encephalopathy. The appearance of a person with this type of dementia is apparently normal, although you can observe a progressive loss of initiative.
Generally, this is caused by abusive alcohol consumption, developing after 15-20 years of continuous consumption. Its symptoms include a frontal alteration, with loss of motivation, poor judgment, attention disorders and problems with recent memory, etc.
Conclusions about dementias
In conclusion, these different types of dementia are neuropsychological disorders characterized by a global decline in cognitive processes. Furthermore, its onset is insidious, progressive and irreversible, in most cases. They usually occur in older adulthood, beyond 65 years of age; however, they seem to be occurring earlier and earlier.
Unfortunately, there’s no treatment to reverse the process. However, cognitive stimulation, neuropsychological rehabilitation, and psychotherapy can lessen the subjective impact of the disease and slow its progression.
- Beteta, E. (2004). Neuropatología de las demencias. Revista de neuro-psiquiatría, 67, 80-105.
- Lasprilla, J. C. A., Guinea, S. F., & Ardila, A. (2003). Las demencias: aspectos clínicos, neuropsicológicos y tratamiento. El Manual Moderno.
- Portellano, J. (2005). Introducción a la neuropsicología. Madrid, ed: McGraw Hill.