‘Individuals who had COVID-19 exhibited significant changes in brain biomarkers associated with Alzheimer’s disease. COVID-19-positive individuals exhibited lower cognitive test performance compared to controls – equivalent to almost two years of age-related cognitive decline.’ (2025)

‘ For patients already battling Alzheimer’s disease , studies indicate that Covid can exacerbate brain inflammation , damage immune cells , and accelerate the disease . Even previously healthy older adults face an increased risk of cognitive impairment and new-onset dementia after infection. Mild Covid cases in younger adults have also been linked to brain issues affecting memory and thinking . ’

‘Scientists discover that even mild COVID-19 can alter brain proteins linked to Alzheimer’s disease, potentially increasing dementia risk. COVID-19-positive individuals exhibited lower cognitive test performance compared to controls – equivalent to almost two years of age-related cognitive decline. ’

❦ ‘Alzheimer’s disease (AD) is acknowledged by the World Health Organisation (WHO) as a global public health concern. AD is the primary cause of dementia and accounts for 50–70% of cases. SARS-CoV-2 can damage the peripheral and the central nervous system (CNS) through both direct and indirect pathways, potentially leaving COVID-19 patients at higher risks for neurological difficulties, including depression, Parkinson’s disease, AD, etc., after recovering from severe symptoms. Patients who recovered from severe COVID-19 infection are more likely to acquire stable neuropsychiatric and neurocognitive conditions like depression, obsessive-compulsive disorder, psychosis, Parkinson’s disease, and Alzheimer’s disease. SARS-CoV-2 infection causes immune system dysfunction, which can lead to suppression of neurogenesis, synaptic damage, and neuronal death, all of which are associated with the aetiology of Alzheimer’s disease. Severe systemic inflammation caused by SARS-CoV-2 is predicted to have long-term negative consequences, such as cognitive impairment. Research has demonstrated that SARS-CoV-2-infected AD patients had a higher mortality rate. In a study from the Department of Neuroscience at the University of Madrid, 204 participants with Frontotemporal Dementia (FTD) and Alzheimer’s disease (AD) were enrolled. According to the study, 15.2% of these individuals had COVID-19 infection, and sadly, 41.9% of those who had the virus died as a result of their illness. COVID-19 causes a secondary effect on underlying brain pathologies, as SARS-CoV-2 has been shown to trigger or accelerate neurodegeneration processes that possibly explain long-term neurodegenerative effects in the elderly population. In response to the impact of COVID-19 in 2020, governments worldwide acted promptly by implementing various public health measures. During this period, people with cognitive impairments such as dementia or AD may have experienced greater stress and anxiety due to sudden changes in the environment and people’s behaviour. It is also significantly harder for AD patients to comprehend and execute defensive measures such as wearing face masks and sanitising frequently. ❂ COVID-19 has generated a worldwide outbreak, resulting in a slew of issues for humans, particularly those suffering from Alzheimer’s disease. Its ability to invade the central nervous system through the hematogenous and neural routes, besides attacking the respiratory system, has the potential to worsen cognitive decline in Alzheimer’s disease patients. The severity of this issue must be highlighted.’ ❂ 📖 (8 Jan 2024 ~ Frontiers in Aging Neuroscience) Unravelling the connection between COVID-19 and Alzheimer’s disease: a comprehensive review ➤ © 2024 Shajahan et al / Frontiers in Aging Neuroscience .

‘All subtypes of dementia, irrespective of patients’ previous dementia types, behaved like rapidly progressive dementia following COVID-19 [infection with SARS-CoV-2] .’

❦ The possible neurological consequences of SARS-CoV-2 infection, associated with physical and cognitive frailty, could lead to a worsening of Parkinson’s disease (PD) in infected patients or – more rarely – to an increase in the Parkinsonian symptomatology . Parkinson’s disease (PD) or Parkinsonism has been described after infections with viruses , such as the Epstein-Barr virus , hepatitis C virus , HIV , influenza A virus , Japanese encephalitis virus , varicella zoster virus , or West Nile virus . Therefore, the hypothesis that SARS-CoV-2 may have even longer-term effects on the brain and lead to an increase in cases of Parkinson’s disease, as occurred in the years following the Spanish flu , has been put forward. ❂ 📖 (23 Mar 2023 ~ Brain Science) Parkinson’s Disease, SARS-CoV-2, and Frailty: Is There a Vicious Cycle Related to Hypovitaminosis D? ➤ © 2023 Palermo et al / Brain Science.

❦ Research led by The University of Queensland has found COVID-19 activates the same inflammatory response in the brain as Parkinson’s disease. “We studied the effect of the virus on the brain’s immune cells, ‘microglia’ which are the key cells involved in the progression of brain diseases like Parkinson’s and Alzheimer’s,” Professor Woodruff said. “Our team grew human microglia in the laboratory and infected the cells with SARS-CoV-2, the virus that causes COVID-19. “We found the cells effectively became ‘angry’, activating the same pathway that Parkinson’s and Alzheimer’s proteins can activate in disease, the inflammasomes.” Dr Albornoz Balmaceda said triggering the inflammasome pathway sparked a ‘fire’ in the brain, which begins a chronic and sustained process of killing off neurons . “It’s kind of a silent killer , because you don’t see any outward symptoms for many years,” Dr Albornoz Balmaceda said. “It may explain why some people who’ve had COVID-19 are more vulnerable to developing neurological symptoms similar to Parkinson’s disease .” The researchers found the spike protein of the virus was enough to start the process and was further exacerbated when there were already proteins in the brain linked to Parkinson’s. “So if someone is already pre-disposed to Parkinson’s , having COVID-19 could be like pouring more fuel on that ‘fire’ in the brain,” Professor Woodruff said. “The same would apply for a predisposition for Alzheimer’s and other dementias that have been linked to inflammasomes.” ❂ 📖 (1 Nov 2022 ~ The University of Queensland, Australia) ‘ A silent killer’ – COVID-19 shown to trigger inflammation in the brain ➤ © 2022 Woodruff & Balmaceda / The University of Queensland, Australia.

‘SARS-CoV-2 infection initiates a disease progression that has the potential to promote cognitive decline and exacerbate pre-existing dementia.’