MEMORY DISEASES: TYPES AND CHARACTERISTICS - NEUROPSYCHOLOGY - 2025

The memory disorders are pathologies in which affected the ability to recall facts in the short or long term. Procedural memory, that is, the memory of how activities and procedures are done, can also be affected. The main and most frequent are Korsakoff syndrome, Alzheimer's disease and Parkinson's.

Memory is one of the most important brain functions. Thanks to it, the body can encode, store and retrieve information related to the past. It is classified into two types according to the temporal scope.

First is short-term memory, which occurs through an excitatory synapse to produce sporadic sensitization or reinforcement. On the other hand, we have medium / long-term memory, which is a consequence of a strengthening of the synapse where certain genes are activated and protein synthesis occurs.

Next, I will explain the most common diseases in which memory is affected

Korsakoff syndrome

Also known as korsakoff psychosis. This syndrome is the cause of excessive and chronic alcohol consumption and is a consequence of a deficiency of vitamin B1 (thiamine). This is because alcohol interferes with the correct intestinal absorption of this vitamin, causing damage to the medial diencephalic region and causing malnutrition.

Korsakoff syndrome causes a multitude of neuronal disorders due to this deficit and hemorrhagic lesions in the nucleus of the thalamus. Above all, memory is the one that is most affected by it. In addition, psychotic episodes can also occur.

Possible predisposing factors

a) Although not all alcoholics suffer from this disease, the first predisposing cause of the syndrome is excessive and continuous consumption of alcohol, which results in malnutrition and a deficiency in vitamin B1.

b) People who have undergone operations to treat obesity or have an eating disorder are also more likely to occur.

c) Genetic component: a certain genetic component is required for this syndrome to occur.

d) Age also seems to be a factor for its occurrence, although it is not exactly known whether it is due to the weakness of the body over the years or due to the accumulation of vitamin B1 deficiency.

e) Finally, people with a chronic disease, a weakened immune system, HIV patients or those receiving hemodialysis or assisted nutrition.

f) Infectious processes or intestinal malabsorption.

Symptoms of Korsakoff syndrome

Some of the symptoms found in this disease are:

a) Anterograde amnesia: characterized by causing difficulty in forming or retaining new memories.

b) Retrograde amnesia: although anterograde amnesia is more common, there is also a certain probability of suffering from this other type of amnesia. It is characterized by the difficulty of accessing past events in the life of the patient, although not very distant in time but rather events that have occurred recently.

c) Ataxia: restlessness and motor incoordination.

d) Hallucinations.

e) Diarrhea and weight loss.

f) Complications in the heart and liver.

g) Wernicke encephalopathy: when this occurs, the disease is called Wernicke-Korsakoff syndrome.

In this case, in addition to the aforementioned symptoms, there are others such as ocular paralysis, hearing loss, epilepsy, hypothermia and depression. It is said that this would be the previous step (in the form of acute encephalopathy).

h) Difficulties in the ability to concentrate.

i) Flattened affect.

j) Apathy or behavioral inertia: these individuals show difficulty in the ability to drive or motivate to undertake new activities.

k) Tendency to silence: these patients show significant deficiencies in maintaining conversations.

l) Tendency to conspire: the tendency to conspire is characteristic of these individuals to compensate for the memory failures they have, compensating for them through the elaboration of unreal or fantasy content, as well as altering the order or temporal context of the episodes experienced that are still they can remember.

Alzheimer disease

Alzheimer's disease is a primary neurodegenerative disease that begins gradually in which little by little cognitive decline occurs.

A person affected by this disease undergoes microscopic changes in the tissue of certain parts of his brain and a progressive and constant loss of acetylcholine, a chemical (neurotransmitter) that is of vital importance for the optimal functioning of brain activity.

The function of acetylcholine is to allow the communication of nerve cells (cholinergic circuits), this activity being present in activities related to learning, memory and thinking.

It is not an easy task to find direct pathological evidence for the presence of Alzheimer's, so it can only be diagnosed when other etiologies of dementia have been ruled out.

Types of Alzheimer's

According to the age of onset of the disease, different types of Alzheimer's can be distinguished:

a) Early-onset Alzheimer's: we speak of early-onset Alzheimer's when it occurs at the age of 65 or earlier.

b) Late-onset Alzheimer's: late-onset Alzheimer's occurs at an age after 65 years.

Possible predisposing factors

There are certain factors that increase the likelihood that a person may suffer from this disease. In this article, I'm going to expose you some of them:

a) Age: age, as we have already said, is one of the most common possible to suffer from this disease. The older, the more likely.

b) Sex: research affirms that there is a higher percentage of women who suffer from Alzheimer's. This is probably due to their greater longevity.

c) Family inheritance: Alzheimer's is a disease that is transmitted by genetics. Thus, it is estimated that up to 40% of patients have a family history.

d) Environmental factors: smokers have a greater risk of suffering from the disease, as well as the consumption of fatty diets. In addition, belonging to a large family also increases the risk.

Alzheimer's symptoms

As I have already mentioned, Alzheimer's is a disease that affects memory. The most characteristic and common symptoms can be summarized as:

a) Short-term memory loss: affects the inability to retain new information.

b) Long-term memory loss: inability to remember personal information

c) Character changes: irritability, lack of initiative, apathy, or decay.

d) Loss of spatial capacity.

e) Aphasia: loss of usual vocabulary for the individual and misunderstanding of common words.

f) Apraxia: lack of control with the muscles themselves.

g) Alterations in reasoning ability.

For its prevention, in addition to maintaining special care in relation to a healthy diet and lifestyle, it is advisable to perform exercises that promote cognitive activity.

Parkinson's disease

This disease is a degenerative disorder of the central nervous system and, although memory is not one of the most affected areas, there is a deterioration of it. It is caused by the brain death of neurons that belong to the substantia nigra.

Normally, the neurons in this area of ​​the brain produce a neurotransmitter called dopamine, which has the function of being the chemical messenger responsible for making the signals between this black substance and the striatum.

Thanks to these signals the uniform and deliberate movements are produced. If the death of neurons in this brain area occurs, dopamine will not be produced and this will be the cause for which the characteristic symptoms of Parkinson's will occur.

In addition to the loss of neurons that produce dopamine, in this disease there is a loss of nerve endings that are responsible for the production of norepinephrine, another neurotransmitter.

Norepinephrine is responsible for the chemical messages produced in the sympathetic nervous system. The somatic nervous system controls many of the body's automatic functions (for example, blood pressure).

Parkinson's symptoms

- Problems with movement, tremors, stiffness in the limbs or trunk. This hinders the individual's ability to speak or perform tasks.

- Problems in balance, which hinders the individual's ability to walk.

- Only rarely, symptoms can appear in very young people around 20 years of age. This is known as juvenile parkinsonism. In these cases, the most common symptoms are dystonia and bradykinesia, and they usually improve with a specific drug called levodopa.

- Bradykinesia: it is characterized by a decrease in spontaneous and automatic movement. It is extremely difficult for the patient to perform routine tasks quickly.

- Masked face: decrease in facial expressions.

- Orthostatic hypotension: it is a sudden drop in blood pressure produced when a person stands up after having been in a lying position. Symptoms are dizziness, vertigo, loss of balance, or even fainting.

This is more likely in Parkinson's because there is a loss of nerve endings in the sympathetic nervous system that controls heart rate, blood pressure, and other automatic functions of the body. Orthostatic hypotension can be improved with the consumption of salt.

- Sexual dysfunction: sexual activity can be affected as a result of the effect that the disease has on nerve signals in the brain. In addition, this can be aggravated by the depressive states of the disease or even by medications.

- Dementia or other cognitive problems: memory, psychomotor, thinking and attention (cognitive) functions are affected here. It will cost the patient both to write and read. Cognitive problems are much more serious in advanced stages of the disease. These problems are manifested above all in memory, in social judgment or the way in which the person forms their opinion of others, language or reasoning.

Cognitive abilities are hardly affected since most of the medications that are usually used to alleviate motor symptoms, produce hallucinations and confusion in the patient.

Possible predisposing factors

- The genetic factor is not especially important when developing Parkinson's although there is a certain probability when there is a history. This risk is between 2 and 5%.

- Environmental factors: exposure to some toxins or other environmental factors can cause the appearance of this disease.

- Mitochondria: it seems that the energy-producing components of the cell (mitochondria) may play an important role in the development of Parkinson's. This is because mitochondria are an important source of free radicals, molecules that damage membranes, proteins and DNA, damage known as oxidative.

- Age: as in the case of Alzheimer's, in Parkinson's there is a greater probability of occurrence the older the individual is, the average age being 60 years.

As a summary, in this article we have seen the importance of the different types of memories in humans, their characteristics and the most frequent diseases in which it is affected.

As a point in common with these three diseases, we can conclude that advanced age is the factor that causes the highest prevalence of them. Thus, as we have already commented, the older the patient, the greater the probability of the disease occurring and the more severe the symptoms will be, thus impairing improvement or stability.

References

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