2023-08-14 11:53:07
Language, behavior or visual alterations. Some symptoms that are not associated with Alzheimer’s, but that can be the first when the disease presents early, before the age of 65 -sometimes even at 30- and in which early diagnosis is one of the great challenges.
Exhibition “Art to remember”. courtesy photo
A mutation associated with greater resistance to a type of early-onset hereditary Alzheimer’s has recently been known, although when this disease occurs early, it is not usually due to genetic causes, indicate experts who review with EFE what is known about it and why Where is the investigation going?
More than 80% of the cases are of sporadic origin (not linked to a mutation) and, although there may be a certain genetic component, there are other factors involved, the researcher notes. Oriol Grau, from the Barcelonaβeta Brain Research Center (BBRC) of the Pasqual Maragall Foundation.
The prevalence of early-onset dementia varies according to different studies, but it would be around 1/1,000 inhabitants, with Alzheimer’s disease being the most frequent cause, he adds. Alberto Lladó, researcher at the Alzheimer’s Unit at the Barcelona Hospital Clinic.
Atypical symptoms of early Alzheimer’s
Characteristically, in early-type Alzheimer’s there is a higher frequency of “atypical presentations.” In 30% of cases, the first symptoms may be different from those of memory, while in older patients these unusual signs are less than 10%, indicates Lladó.
When the disease begins after the age of 70, it is characterized by a progressive loss of recent memory, with atrophy of the hippocampus, the area of the brain that allows us to learn new information and remember it.
In younger people, the symptoms may begin with difficulty expressing themselves and understanding things, problems making certain coordinated movements, calculating distances, or behavioral disorders, says Lladó, who adds that younger patients may, in general, have an evolution faster.
The diagnosis of this disease can become a challenge if the person who suffers from it is under 65 years of age and also presents these atypical symptoms.
The patient may take longer to reach the specialist because “since he is younger -indicates Grau- the doctors do not suspect at first that it could be Alzheimer’s when making an atypical presentation.”
The causes are in the genes
The origin of early-onset Alzheimer’s is unknown (with the exception of genetics). What is known is that there are no differences in terms of the neuropathological alterations that characterize the disease: the deposits of beta-amyloid and tau proteins in the brain. .
What can change in people with atypical presentations, especially during the initial phase of the disease, are the patterns of distribution in the brain of the tau protein, which are “a little different”, highlights the researcher from the Pascual Maragall Foundation.
Sometimes early-onset Alzheimer’s has a genetic origin due to mutations in one of these three genes: PSEN1, PSEN2, and the amyloid precursor protein gene. Depending on the affected gene, it usually manifests itself under 60 years of age, even over 50 and in extreme cases over 30.
In Colombia there is a population in the province of Antioquia where many are carriers of the Paisa (PSEN1) mutation, which predisposes them to autosomal dominant Alzheimer’s disease. Those affected usually develop mild cognitive impairment around age 44, dementia at age 49, and die from complications at age 60.
In this group, two cases of two mutations with a protective effect against Paisa have been detected with the ability to delay the onset of the disease for years. The second case was recently published in the journal Nature.
Lladó points out that knowing genetic alterations or factors that can delay the onset of Alzheimer’s is “of great interest to study the possible mechanisms of action of these and propose possible new treatments.”
He Neuroscientist at Instituto Cajal Javier de Felipe studies the anatomy of the brain and in Alzheimer’s disease the alterations of the circuits of this organ to try to explain the cognitive deterioration.
Among the brains that he has been able to analyze there is one from that population with the Paisa mutation.
De Felipe analyzes the brains to try to see what are the alterations that have to occur in the neural connections to produce a cognitive deterioration.
Many lines of research
The researcher highlights, in relation to Alzheimer’s in general, that there are cases of brains presenting amyloid plaques and tau protein tangles, but, according to their medical history, the patients did not present cognitive impairment.
“It’s not uncommon,” so they are studying what makes that leap between having these alterations in the brain and cognitive deterioration occur.
In research there are many open lines of work, Lladó stresses, among them those that seek to improve understanding of the causes of the disease, have a faster and safer diagnosis or search for new therapeutic targets and drugs.
And there are still unknowns to be resolved about early Alzheimer’s. Why the clinical presentation is different or to what extent is it the same disease or if they are different variants, enumerates Grau. “These are things for which there is still no clear answer and investigation continues.”
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