Impact of Plasmodium vivax malaria on executive and cognitive functions in elderlies in the Brazilian Amazon

Abstract

The exact path leading to cognitive impairment that goes beyond malaria is unclear, but it appears to be the result of interactive factors. Time of exposure to disease and recurrences are potentially major determinant variables. Cognitive impairment is described mainly in children, rarely in adults. The disease in high endemic areas usually does not affect elderlies, because of acquired immunity over time. However, this population is relatively more frequently sick in lower endemic areas, such as in the Amazon. This study assessed the effect of Plasmodium vivax malaria on the executive and cognitive functions of elderlies, in the Brazilian Amazon. A cohort study was conducted to evaluate executive and cognitive functions one week (T0), two months (T2) and eight months (T8) after the malaria episode. Mini-Mental State Examination (MMSE), Beck Depression Inventory II (BDI-II), Clock Drawing Test (CDT), Wechsler adult intelligence scale (WAIS-III), and Wisconsin Card Sorting Test (WCST) were used to assess executive and cognitive functions. One hundred-forty elderlies were enrolled (70 with P. vivax malaria and 70 without malaria). P. vivax malaria was associated with impairment of the executive and cognitive functions in elderlies for up to 8 months after acute P. vivax malaria. Prior history of malaria, recurrences and higher parasitemia were independently associated with various surrogates of executive and cognitive impairment. With the increase in life expectancy, elderlies living in malaria endemic areas will deserve more attention from health authorities, to guarantee improvement of their quality of life in the tropics.

Dynamics and immunomodulation of cognitive deficits and behavioral changes in non-severe experimental malaria

“…The cognitive deficits of nSM may be persistent, but the evolution of cognitive and behavioral impairment is poorly understood ( 12 , 28 ). Persistent cognitive impairment may affect social, economic and cultural development in malaria-endemic areas.…”

Interplay Between the Immune and Nervous Cognitive Systems in Homeostasis and in Malaria

“…Cognitive impairment, assessed by an indicator of intellectual function, Intelligence-IV (WPPSI-IV) which measures parameters such as verbal comprehension and working memory, was reported in children between 2 and 7 years old who had suffered at least one P. vivax malaria episode compared to children who had never had malaria 104 . More recently it was reported that acute P. vivax malaria may be associated with long-term impairment of executive and cognitive functions in the elderly 105 .…”

Cognição na Malária não Grave e na Infecção Plasmodial Assintomática

“…Além disso, sequelas cognitivas relacionadas à memória de trabalho, à compreensão verbal, à organização perceptiva e ao raciocínio abstrato também foram observadas em crianças como resultado de um único episódio de MnG nessa localidade (13), bem como no Estado do Pará (14). Recentemente, sequelas cognitivas e das funções executivas foram relatadas oito meses após o episódio de malária vivax não grave em idosos no estado do Amazonas (15).…”

“…Sobre a dinâmica e a persistência das sequelas da MnG; apesar de alguns estudos registrarem efeitos com duração de em torno de nove meses após o último episódio malárico (10,13,15), um estudo na Tailândia não detectou efeito negativo no desempenho escolar em crianças e adolescentes com histórico de malária há mais de dois anos (16). Isso contrasta com a situação observada em casos de malária grave.…”

“…Tal fardo cognitivo foi observado em adolescentes e idosos em diferentes regiões endêmicas de malária no mundo (12,15) (Figura 1). Em idosos os prejuízos cognitivos incidem nas funções executivas relacionadas à memória de trabalho (15).…”