Patients who suffer from Alzheimer’s also present neuropsychiatric symptoms, such as apathy (withdrawal), impulsivity, anxiety, depression… So far, however, it is unclear if these are a true marker of the disease or if they are side effects of cognitive decline..
Several studies are regularly published on this subject. Thus, a study published in the journal Alzheimer’s & Dementia has in the past shown that sleep disorders and especially daytime naps could constitute a predictive sign, well before the onset of memory disorders. Another study, published in 2018 in The American Journal of Psychiatry, had concluded that anxiety could be the first symptom up to ten years before diagnosis. Changes in personality or behavior were also pointed out in a study of the Journal of The American Geriatrics Society in 2018, which showed that the participants had developed mental disorders several years earlier, such as depression, anxiety or mood swings.
This time, researchers from Lund University in Sweden carried out tests (using blood plasma and cerebrospinal fluid) in 356 people who were apparently in good health. Their objective was to observe their levels of tau protein and beta-amyloid – proteins at the heart of Alzheimer’s disease – and to see, depending on the quantity that each had, if certain symptoms observed in patients with cognitive decline also existed in healthy subjects.
Alzheimer’s warning signs
As a result, they realized that there was a link between high levels of beta-amyloid and tau protein, and suffering from anxiety and apathy, i.e. a loss of motivation. How is it interesting? This demonstrates that these symptoms described in Alzheimer’s patients are not necessarily side effects of cognitive impairment, but a symptom apart from the disease, completely independent of the memory loss and visible earlier in the development of the latter.
Besides the question of timing, the interest is also to be able detect Alzheimer’s disease in a broader way, not only in relation to memory loss. Changes in mood, apathy or even anxiety could, according to them, be early signs of Alzheimer’s.
Inserm recalled in a recent study that amnesia is not systematic at the start of Alzheimer’s disease and ultimately not very predictive. Not only would we miss cases of Alzheimer’s disease (those that do not manifest themselves by memory lapses), but in addition, we would identify (wrongly) as “Alzheimer” other neurodegenerative pathologies, requiring different treatment. And invited to “rethink the way in which this disease is diagnosed” in order to reduce the diagnostic wandering and the bad orientation of certain patients.
Source : Development of apathy, anxiety, and depression in cognitively unimpaired older adults: effects of Alzheimer’s disease pathology and cognitive decline, Biological Psychiatry, January 28, 2022.
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