Chikungunya can cause cognitive impairment in the elderly and be a risk factor for dementia

With a life expectancy of 76.8 years, Brazil has increasingly more elderly people. In 2018, almost 2,400 million elderly people had already been diagnosed with dementia and the forecast is that by 2028 this number will exceed 3,272 million

In general, the extremes of age are the periods of life associated with high susceptibility to diseases. In the population older than 65 years, several reasons contribute to this fact, such as more compromised immune system and decrease of some physiological functions. It is known, for example, that the persistence of the symptoms of the disease caused by the chikungunya virus (CHIKV)  it is worrying in this public, in part due to the greater association with chronic musculoskeletal disorders, frequent in this age group. Now, a recent article published in the journal Frontiers in Psychiatry titled “Cognitive Dysfunction of Chikungunya Virus Infection in Older Adults”, revealed for the first time that virus infection can cause long-term cognitive decline in the elderly and be a risk factor for future dementia in this group. Scientists conducted a cross-sectional study through clinical, neuropsychological and geriatric evaluations.

The research, carried out in 2019, analyzed 121 elderly volunteers aged between 60 and 90 years, 95 of whom were affected by the disease in Natal (RN), on average six months earlier. The other 26 were enrolled in the control group, where no one had been infected. Dr. Kleber Luz, an infectologist at the Onofre Lopes University Hospital of the Federal University of Rio Grande do Norte (Huol/UFRN), one of the coordinators of the study, explains that the objective of the study was to evaluate the impact on an older population and for this, structured questionnaires were applied to a group affected by chikungunya and a healthy group with a corresponding age was used as a control group. Still according to Dr. Luz, these questionnaires applied to cases and controls, called Pfeffers Functional Activities Questionnaire (FAQ) and Geriatric Depression Scale (GDS), are tools previously used in the practice of cognitive assessment of geriatric patients. The study also submitted the volunteers to a medical evaluation and then to a wide set of tests, organized by a team of psychologists from UFRN.

Some patients affected by chikungunya fever reported loss of concentration and focus, as well as memory lapses and this was attributed to Alzheimer’s when it could be one of the sequelae caused by the CHIKV virus. “These losses in cognitive capacity were more evident in the group affected by the chikungunya virus. Thus, establishing a temporal relationship between the chikungunya event and the loss of cognitive capacity, says Dr. Luz. According to the study, two-thirds of the participants had subjective memory complaints, and 68% of them were concerned about this issue, although only 44% reported that the memory complaint began in the last year. One of these evaluations was the Montreal cognitive test, known as the MoCA. Over the research period, while age was kept constant, chikungunya virus infection was associated with a 607.29% increase in the chance of having MoCA performance considered impaired or declining when compared to the group with healthy controls.

Rio Grande do Norte was one of the states with the highest prevalence of chikungunya cases, which affected many elderly people. In 2019, it registered more than 12 thousand cases, with an average of 348 per hundred thousand inhabitants, second only to the incidence in Rio de Janeiro. In the acute phase, there was a manifestation of serious diseases in the neurological system, such as meningitis. Some elderly patients reported loss of concentration and focus, as well as memory lapses.

The infectologist also points out that the motivation for carrying out the study was the general rule that infectious diseases usually are capable of producing impacts on the central nervous system. “These impacts can be short-lived or prolonged. For example, there are reports that women affected by dengue can develop depression for up to two years, but in practice, the authors realized that patients in the acute post-chikungunya period complained of a reduction in cognitive capacity, he explains.

Asked on how the results can help in the debate on the aging of the population and the increase in dementias, Dr. Luz is categorical in stating that the findings can contribute so that preventive measures of mosquito-borne diseases can somehow impact the reduction of cases of cognitive loss, especially in cases that occur in the elderly population. In a clear way, dementias are related to already clarified phenomena of deposition or accumulation of certain chemicals, however the occurrence of an infectious or mainly tropical disease may aggravate cases of dementia especially in areas that already have a serious commitment of financial resources, he concludes.

Dementia cases are expected to almost triple by 2050

In 2018, the Brazilian Institute of Geography and Statistics (IBGE) registered a total of 28 million people aged 60 years or more, 13% of Brazils total population of 209.5 million. According to the estimated prevalence (8.5%), of the total of 28 million (?60), there would be almost 2.38 million individuals with dementia in Brazil. For 2028, this number is expected to exceed 3.27 million, which means almost 1 million more in 10 years. By 2042, the number is expected to double, surpassing the 4.76 million mark.

The numbers are even more frightening for 2050, when more than 153 million people may have dementia, according to the researchers warning in the study entitled “Estimation of the global prevalence of dementia in 2019 and forecasted prevalence in 2050: an analysis for the Global Burden of Disease Study 2019” published in the scientific journal The Lancet Public Health. In 2019, the number was 57 million. In Brazil, it is expected to reach 5.6 million. In 2019, the number was 1.8 million. The research, which analyzes data from 195 countries, seeks to give governments an idea of what actions may be needed.

According to the article “Dementia in Latin America: An Emergent Silent Tsunami”, published in Frontiers in Aging Neuroscience journal in 2016, forecasts suggest that by 2050 the number of people aged 60 will increase by 1.25 billion, of which 79% will be living in the least developed regions of the world.

With a life expectancy of 76.8 years, Brazil has increasingly older people and data from national and international epidemiological surveys show a very high global prevalence of dementia. Therefore, the debate and strategic planning for the best use of the information obtained by the study is urgent. The discussion of these data with health managers at all levels of activity: municipality, state and federal government, can help to plan actions and public policies in the format of clinical protocols and therapeutic guidelines, as the Brazilian population is aging.

About the disease

The disease caused by the Chikungunya virus is an arbovirus transmitted by Aedes aegypti, but Aedes albopictus can also transmit. The main symptoms, in addition to fever, nausea and vomiting, are characterized by severe joint pain, which can even be disabling and last months or even years after the acute condition, with a course very similar to that of rheumatoid arthritis. Traditional treatment is done according to the symptoms, with the use of analgesics, antipyretics and anti-inflammatory drugs to relieve fever and pain. However, treatment requires adequate and not always easy management of analgesics, in some cases with the combined use of immunomodulators. It is common for joint pains to remain for a certain time, even after the elimination of other symptoms. Therefore, in some cases physiotherapy is recommended. Follow-up is ideally performed by a rheumatologist. Other complications and deaths are uncommon and are mainly associated with rare manifestations, such as central nervous system involvement.