Dementia in a tribal landlocked elderly population at high altitude: What explains the lower prevalence?

Abstract

Introduction:Studies across the populations have suggested that dementia is differentially distributed with a lower prevalence in developing regions than the developed ones. A comparison in the prevalence of dementia across populations may provide an insight into its risk factors. Earlier, we reported on the prevalence of dementia in elderly population in migrant, urban, rural, and tribal populations. The present study was conducted with a view to estimating the prevalence of dementia in Tribal Landlocked Elderly Population at high altitude and therefore to draw some conclusions on the differential distribution of dementia across populations.Methods:A cross-sectional comprehensive two-phase survey of all residents aged 60 years and older was conducted. Phase 1 involved screening of all individuals aged 60 and above with the help of a cognitive screen specifically developed for the tribal population. Phase 2 involved clinical examination of individuals who were suspected of dementia as per the developed cognitive screening test.Results:The results revealed that six individuals out of a total of 481 studied above 60 years of age in the studied population scored between 17 and 23, thus qualifying as suffering from mild cognitive impairment. Importantly, none of the individuals above 60 years of age scored <17.Discussion:The current study is in conformity with our previous study conducted on urban, rural, and migrant areas of the state of Himachal Pradesh again emphasizing on dementia being rare in tribal populations and thereby pointing to the presence of some protective factors among tribal people.

Prevalence of Cognitive Impairment and Dementia in Older Adults Living at High Altitude: A Systematic Review and Meta-Analysis

“…Sample sizes ranged from 311 to 964 participants. Likewise, 5 out of the 6 studies included in this review were conducted in Latin America (Colombia and Peru) [28-30, 32, 33], and one study was conducted in India [31]. The altitude at which the studies were conducted varied from 1,783 to 3,847 m. The proportion of women included in the studies ranged from 38.7 to 65.6%, and all the studies were performed in older adults [28-33] (Table 1).…”

“…Three studies reported proper comparability between both groups, depending on the outcome [30, 32, 33]. Two studies did not report or perform an adequate statistical analysis [28, 31]. In this way, 4 studies had a low risk of bias [29, 30, 32, 33], while 2 of them had a high risk of bias [28, 31] (Table 2).…”

“…Two studies did not report or perform an adequate statistical analysis [28, 31]. In this way, 4 studies had a low risk of bias [29, 30, 32, 33], while 2 of them had a high risk of bias [28, 31] (Table 2). Meta-analyses reported a p value of Egger’s regression test of 0.73.…”

“…Other studies have reported a prevalence of dementia of 4.9% [35] in older adults in China, from 8.5 to 11% in Latin America [34, 36], 6.5% in the USA, and 6.9% in East Europe [34]. The studies included in this review correspond to Latin America [28-30, 32, 33] and South Asia [31], so the prevalence cannot be compared to those obtained in other regions of the world. These regions brought together many low- and middle-income countries, which represented more than half of the population with dementia at the beginning of this decade [34].…”

Glucose Metabolic Dysfunction in Neurodegenerative Diseases—New Mechanistic Insights and the Potential of Hypoxia as a Prospective Therapy Targeting Metabolic Reprogramming

“…Another study showed that in California, where the average altitude is as high as 1800 m, Alzheimer's disease mortality was negatively correlated with residential altitude [225]. Populations in certain high-altitude may also have special protection against dementia, such as a tribe in the Himalayas of North Indian [226]. Recently, it has been shown that IHC (simulation at 5000 m height, and 4 h per day for 15 consecutive days) can reduce cognitive deficits and anxiety in 9 month-old APP/PS1 mice while reducing amyloid β and pro-apoptotic protein contents in the cerebral cortex and hippocampus and augmenting hippocampal neurogenesis and BDNF content [227].…”