According to the Global Burden of Disease Study 2016, the estimated prevalence of dementia in Brazil was approximately 16.9% in 2016 (GBD 2016, 2019). A systematic review conducted between 1990 and 2010 with older people aged 60 years and over found that, among high quality studies, all conducted in urban areas of São Paulo state, the prevalence of dementia ranged from 5.1% to 19.0% (Fagundes et al., 2011). Another study projected the prevalence of dementia among people 65 years and older in Brazil based on Census data (2010). The authors estimated that prevalence in the national territory would be 7.9% in 2020 (Burlá et al., 2013). There are several articles reporting prevalence measures in the literature; all of these were conducted in the south or southeast of Brazil. Therefore, there is lack of updated studies representative of the Brazilian population. The incidence rate of dementia was 13.8 per 1,000 person-years according to a study carried out in the city of Catanduva, São Paulo, with individuals aged 65 years and over (Nitrini et al., 2004). A study conducted in the city of Porto Alegre found the incidence rate of Alzheimer’s disease as 14.8 per 1,000 person-years (Chaves et al., 2009).

References:

Burlá, C., Camarano, A. A., Kanso, S., Fernandes, D., & Nunes, R. (2013). Panorama prospectivo das demências no Brasil: Um enfoque demográfico. Ciência & Saúde Coletiva, 18(10), 2949–2956. https://doi.org/10.1590/S1413-81232013001000019

Chaves, M. L., Camozzato, A. L., Godinho, C., Piazenski, I., & Kaye, J. (2009). Incidence of Mild Cognitive Impairment and Alzheimer Disease in Southern Brazil. Journal of Geriatric Psychiatry and Neurology, 22(3), 181–187. https://doi.org/10.1177/0891988709332942

Fagundes, S. D., Silva, M. T., Thees, M. F. R. S., & Pereira, M. G. (2011). Prevalence of dementia among elderly Brazilians: A systematic review. Sao Paulo Medical Journal, 129(1), 46–50. https://doi.org/10.1590/S1516-31802011000100009

GBD 2016. (2019). Global, regional, and national burden of Alzheimer’s disease and other dementias, 1990–2016: A systematic analysis for the Global Burden of Disease Study 2016. The Lancet Neurology, 18, 88–106. http://dx.doi.org/10.1016/S1474-4422(18)30403-4

Nitrini, R., Caramelli, P., Herrera, E., Bahia, V. S., Caixeta, L. F., Radanovic, M., Anghinah, R., Charchat-Fichman, H., Porto, C. S., Carthery, M. T., Hartmann, A. P. J., Huang, N., Smid, J., Lima, E. P., Takada, L. T., & Takahashi, D. Y. (2004). Incidence of dementia in a community-dwelling Brazilian population. Alzheimer Disease and Associated Disorders, 18(4), 241–246.

From the population-based study conducted in 2005-2006, the prevalence of dementia in Hong Kong was 7.2% in people aged 60 and above (9.85% for female and 4.2% for male) and 9.3% in people aged 70 and above (15.3% for female and 8.9% for male). Alzheimer’s disease was the most common type of dementia which accounted for 63% of dementia patients. And 83% of the patients were in the mild stage (Elderly Commission, 2006). There is no available data for the incidence of dementia in Hong Kong.

Moreover, there are some additional sources estimating the prevalence of dementia in Hong Kong. A systematic review published in 2013, for example, estimated that the prevalence of dementia among people aged 65 and over was 6.8% in Hong Kong (Wu et al., 2013). Another study makes use of secondary data to predict the prevalence and trends of dementia in Hong Kong. It is projected that the number of people with dementia aged 60 years and above would increase from 103,433 in 2009 to 332,688 in 2039, an increase by more than 3 times (Yu et al., 2012). Besides, the population health survey in 2014-2015 estimates that the overall population prevalence of self-reported dementia is 0.6% for female and 0.2% for male (Centre for Health Protection, 2017). The Hospital Authority also estimates that 5-8% people aged 65 years and above and 20-30% people aged 80 years and above would have dementia of different extents (Hospital Authority, 2020, April 20).

References:

Centre for Health Protection. (2017). Report of Population Health Survey 2014/15. Retrieved from https://www.chp.gov.hk/en/static/51256.html

Elderly Commission. (2006). Prevalence of dementia in Hong Kong.  Retrieved from https://www.elderlycommission.gov.hk/en/download/meeting/Study%20on%20Prevalence%20of%20dementia.pdf.

Hospital Authority. (2020, April 20). Dementia. Retrieved from https://www21.ha.org.hk/smartpatient/SPW/en-US/Disease-Information/Disease/?guid=0ff3b12b-b3c0-4fa9-9bac-6bcf9dc501ba

Wu, Y.-T., Lee, H.-y., Norton, S., Chen, C., Chen, H., He, C., . . . Brayne, C. J. P. O. (2013). Prevalence studies of dementia in mainland china, Hong Kong and taiwan: a systematic review and meta-analysis. 8(6), e66252. https://doi.org/10.1371/journal.pone.0066252

Yu, R., Chau, P. H., McGhee, S. M., Cheung, W. L., Chan, K. C., Cheung, S. H., & Woo, J. (2012). Trends in prevalence and mortality of dementia in elderly Hong Kong population: projections, disease burden, and implications for long-term care. International Journal of Alzheimer’s Disease, 2012. https://doi.org/10.1155/2012/406852

Prevalence of dementia has been reported based on several population based epidemiological studies conducted across India over the last two decades. According to the Dementia India Report 2010 (Alzheimer’s and Related Disorders of India [ARDSI], 2010) projections, an estimated 5.29 million Indian people aged over 60 have dementia. The more recent Global Burden of Disease study estimated that 3.69 million people had Alzheimer’s disease or other dementias in India in 2019 (India State-Level Disease Burden Initiative Neurological Disorders Collaborators, 2021). There is variability in reported prevalence rates ranging from 0.3% (Rodriguez et al., 2008) to 14.9% (Seby et al., 2011) among older adults, depending on the sample size, age of the cohort, geographical area considered (rural vs. urban population) and the year of the study (Table 6.1). Meta-analysis of individual studies have reported pooled prevalence estimates for dementia to range from 3.4% (95% CI = 2.0 to 5.0) to 4.4% (2.2-7.2) in India (Dhiman et al., 2021; Farina et al, 2020).

Differences in estimates may be related to the adoption of different methods and defining criteria, but differences in environmental and genetic risk factors may also contribute. Recognising the need to study dementia prevalence using a uniform method, the Government of India’s scientific research funding agency, specifically the Department of Biotechnology, has initiated a multi-centric study across rural, urban, and tribal areas to observe dementia prevalence (Bhatt, 2020).

Table 6.1 shows dementia prevalence across the country

Table Source: (Razdan et al., 1994;  Shaji et al., 1996; Rajkumar, Kumar and Thara, 1997; Chandra et al., 1998; Vas et al., 2001; Shaji, Bose and Verghese, 2005; Rodriguez et al., 2008; Das et al., 2006; Das et al., 2007; Das et al., 2008; Raina et al., 2008; Mathuranath et al., 2010 ; Saldanha et al., 2010; Seby, Chaudhary and Chakraborty, 2011, Poddar et al., 2011; Raina et al., 2014; Raina, Chander and Bhardwaj, 2016; Banerjee et al., 2017).

Moreover, there are few studies reporting incidence of dementia in India and results are varied (Table 6.2).

Table 6.2 shows studies reporting incidence rates for dementia in India

Source: (Chandra et al., 2001; Mathuranath et al., 2012; Banerjee et al., 2017)

References:

Alzheimer’s and Related Disorders Society of India. (2010). THE DEMENTIA INDIA REPORT 2010: Prevalence, impact, cost and services for dementia. New Delhi. Available from:  https://ardsi.org/pdf/annual%20report.pdf

Banerjee, T. K., Dutta, S., Das, S., Ghosal, M., Ray, B. K., Biswas, A.,… & Das, S. K. (2017). Epidemiology of dementia and its burden in the city of Kolkata, India. International Journal of Geriatric Psychiatry, 32(6), 605–614. https://doi.org/10.1002/gps.4499

Banerjee, T. K., Mukherjee, C. S., Dutt, A., Shekhar, A., & Hazra, A. (2008). Cognitive dysfunction in an urban Indian population: some observations. Neuroepidemiology, 31(2), 109–114. https://doi.org/10.1159/000146252

Bhatt, B. (2020). DBT’s multi-centric Dementia Science Programme. Vigyan Samachar. Available from: https://vigyanprasar.gov.in/wp-content/uploads/DBT%E2%80%99s-multi-centric-Dementia-Science-Programme-10apr20.pdf

Chandra, V., Ganguli, M., Pandav, R., Johnston, J., Belle, S., & DeKosky, S. T. (1998). Prevalence of Alzheimer’s disease and other dementias in rural India: the Indo-US study. Neurology, 51(4),1000–1008. https://doi.org/10.1212/wnl.51.4.1000

Chandra, V., Pandav, R., Dodge, H. H., Johnston, J. M., Belle, S. H., DeKosky, S. T., & Ganguli, M. (2001). Incidence of Alzheimer’s disease in a rural community in India: the Indo-US study. Neurology, 57(6), 985–989. https://doi.org/10.1212/wnl.57.6.985

Das, S. K., Biswas, A., Roy, J., Bose, P., Roy, T., Banerjee, T. K., … & Hazra, A. (2008). Prevalence of major neurological disorders among geriatric population in the metropolitan city of Kolkata. The Journal of the Association of Physicians of India, 56, 175–181. Retrieved from: http://www.ncbi.nlm.nih.gov/pubmed/18697633

Das, S. K., Biswas, A., Roy, T., Banerjee, T. K., Mukherjee, C. S., Raut, D. K., & Chaudhuri, A. (2006). A random sample survey for prevalence of major neurological disorders in Kolkata. Indian Journal of Medical Research, 124(2), 163.

Das, S. K., Bose, P., Biswas, A., Dutt, A., Banerjee, T. K., Hazra, A. M., …& Roy, T. (2007). An epidemiologic study of mild cognitive impairment in Kolkata, India. Neurology, 68(23), 2019–2026. https://doi.org/10.1212/01.wnl.0000264424.76759.e6

Dhiman, V., Menon, G. R., Kaur, S., Mishra, A., John, D., Rao Vishnu, M. V., Tiwari, R. R., & Dhaliwal, R. S. (2021). A Systematic Review and Meta-analysis of Prevalence of Epilepsy, Dementia, Headache, and Parkinson Disease in India. Neurology India, 69(2), 294–301. https://doi.org/10.4103/0028-3886.314588

Farina, N., Ibnidris, A., Alladi, S., Comas-Herrera, A., Albanese, E., Docrat, S., Ferri, C. P., Freeman, E., Govia, I., Jacobs, R., Astudillo-Garcia, C. I., Musyimi, C., Sani, T. P., Schneider, M., Theresia, I., Turana, Y., Knapp, M., & and, S. B. (2020). A systematic review and meta-analysis of dementia prevalence in seven developing countries: A STRiDE project. Global Public Health, 1–16. https://doi.org/10.1080/17441692.2020.1792527

India State-Level Disease Burden Initiative Neurological Disorders Collaborators (2021). The burden of neurological disorders across the states of India: The Global Burden of Disease Study 1990-2019. The Lancet. Global health, 9(8), e1129–e1144.

Mathuranath, P. S., Cherian, P. J., Mathew, R., Kumar, S., George, A., Alexander, A.,  Sarma, P. S. (2010). Dementia in Kerala, South India: prevalence and influence of age, education and gender.International Journal of Geriatric Psychiatry, 25(3), 290–297. https://doi.org/10.1002/gps.2338

Mathuranath, P., Menon, R., Ranjith, N., Sarma, Ps., Verghese, J., George, A., …& Kumar, Ms. (2012). Incidence of Alzheimer′s disease in India: A 10 years follow-up study. Neurology India, 60(6), 625. https://doi.org/10.4103/0028-3886.105198

Poddar, K., Kant, S., Singh, A., & Singh, T. B. (2011). An epidemiological study of dementia among the habitants of eastern Uttar Pradesh, India. Annals of Indian Academy of Neurology, 14(3), 164–168. https://doi.org/10.4103/0972-2327.85874

Raina, S. K., Chander, V., & Bhardwaj, A. (2016). Dementia in a tribal landlocked elderly population at high altitude: What explains the lower prevalence?. Journal of neurosciences in rural practice, 7(3), 419–422. https://doi.org/10.4103/0976-3147.182775

Raina, S. K., Raina, S., Chander, V., Grover, A., Singh, S., & Bhardwaj, A. (2014). Is dementia differentially distributed? A study on the prevalence of dementia in migrant, urban, rural, and tribal elderly population of himalayan region in northern India. North American Journal of Medical Sciences, 6(4), 172–177. https://doi.org/10.4103/1947-2714.131243

Raina, S., Raina, S., Razdan, S., & Pandita, K. (2008). Prevalence of dementia among Kashmiri migrants. Annals of Indian Academy of Neurology, 11(2), 106. https://doi.org/10.4103/0972-2327.41878

Rajkumar, S., Kumar, S., & Thara, R. (1997). PREVALENCE OF DEMENTIA IN A RURAL SETTING: A REPORT FROM INDIA. International Journal of Geriatric Psychiatry, 12(7), 702–707. https://doi.org/10.1002/(SICI)1099-1166(199707)12:7<702::AID-GPS489>3.0.CO;2-H

Razdan, S., Kaul, R. L., Motta, A., Kaul, S., & Bhatt, R. K. (1994). Prevalence and Pattern of Major Neurological Disorders in Rural Kashmir (India) in 1986. Neuroepidemiology, 13(3), 113–119. https://doi.org/10.1159/000110368

Rodriguez, J. J. L., Ferri, C. P., Acosta, D., Guerra, M., Huang, Y., Jacob, K., … &10/66 Dementia  Research Group. (2008). Prevalence of dementia in Latin America, India, and China: A population-based cross-sectional survey. The Lancet, 372(9637), 464–474. https://doi.org/10.1016/S0140-6736(08)61002-8

Saldanha, D., Mani, M. R., Srivastava, K., Goyal, S., & Bhattacharya, D. (2010). An epidemiological study of dementia under the aegis of mental health program, Maharashtra, Pune chapter. Indian Journal of Psychiatry, 52(2), 131–139. https://doi.org/10.4103/0019-5545.64588

Seby, K., Chaudhury, S., & Chakraborty, R. (2011). Prevalence of psychiatric and physical morbidity in an urban geriatric population. Indian journal of psychiatry, 53(2), 121. https://doi.org/10.4103/0019-5545.82535

Shaji, S., Bose, S., & Verghese, A. (2005). Prevalence of dementia in an urban population in Kerala, India. British Journal of Psychiatry, 186(2), 136–140. https://doi.org/10.1192/bjp.186.2.136

Shaji, S., Promodu, K., Abraham, T., Roy, K. J., & Verghese, A. (1996). An Epidemiological Study of Dementia in a Rural Community in Kerala, India. British Journal of Psychiatry, 168(6), 745–749. https://doi.org/10.1192/bjp.168.6.745.

Vas, C. J., Pinto, C., Panikker, D., Noronha, S., Deshpande, N., Kulkarni, L., …& Sachdeva, S. (2001). Prevalence of Dementia in an Urban Indian Population. International Psychogeriatrics,13(4), 439–450. https://doi.org/10.1017/S1041610201007852

The earliest report estimated that the dementia prevalence in Indonesia comes from a joint report of ADI Asia-Pacific members in 2005. The report stated a prevalence of 606,100. The same source reported an incidence of 191,400, which was predicted to increase to 314,100 by 2020 and to 932,000 by 2050 (Access Economics, 2006).

 The most recent estimates based on regional prediction published in the revised World Alzheimer Report 2015 stated that in 2015, approximately 1.2 million people in Indonesia were living with dementia and this number was expected to increase up to almost 4 million by 2050 (Prince et al., 2015).

Other studies identified reported regional dementia prevalence rates.

Yesufu (2009, p.12) reported a dementia prevalence of 4.1% among those aged 60 and older. The research further found that the prevalence of people living with Alzheimer’s Disease was 3.1% in the same age group, while that of all other dementias (‘including Vascular Dementia, possible secondary dementia, and other non-assessed sub-types) was estimated to be 5.4% (age range 52-98 years)’. This research had been conducted in Sumedang (West Java) and Borobodu (Central Java) as well as urban sites in Central and South Jakarta (Northwest Java).

Hogervorst (2011, p.8), studying similar areas to Yesufu (the study was conducted in West and Central Java as well as at an urban site in Jakarta) and who aimed to validate two short dementia screening tests in Indonesia reported a ‘suspected dementia prevalence’ of 8% among those aged 60 and 65 years. The author reports that they found a very high rate (16-21%) possible dementia cases in Borobudur, Central Java, which raised the overall estimated prevalence rate.

Surveymeter, an independent research institution, investigated the prevalence of dementia in the province of Yogyakarta (Suriastini et al., 2016) and Bali (Suriastini et al., 2018). Yogyakarta is located in Java, which is the most densely-populated island in Indonesia (The Editors of Encyclopaedia Britannica, 2017), and currently is the province with the highest percentage of older people among all provinces in Indonesia  (Pusat Data dan Informasi Kementerian Kesehatan RI, 2017). Surveymeter’s data from Yogyakarta showed a dementia prevalence of 20.1% (Suriastini et al., 2016). No data regarding incidence in Yogyakarta were found.

A similar study conducted in 2018 in the province of Bali showed a higher prevalence of dementia at 32.16% (Suriastini et al., 2018). This high prevalence might be related to the proportion of older population in this province. Among provinces outside of Java Island, Bali has the highest number of older people outside of Java (Pusat Data dan Informasi Kementerian Kesehatan RI, 2017). There were no data found regarding incidence in this province either. Surveymeter’s data is based on household surveys in the province of Yogyakarta (Suriastini et al., 2016) and Bali (Suriastini et al., 2018). Both studies were conducted using structured questionnaire and instruments of cognitive screening and functional status assessment such as MMSE, ADL and IADL for both the patients and caregivers in villages or sub-districts.

References:

Access Economics. (2006). Demensia Di Kawasan Asia Pasifik: Sudah Ada Wabah. https://www.alz.co.uk/research/files/apreportindonesian.pdf

Hogervorst, E. (2011). Validation of two short dementia screening tests in Indonesia. IN: Jacobsen, S.R. (ed.) Vascular Dementia: Risk Factors, Diagnosis and Treatment, New York: Nova Science, pp. 235-256.

Prince, M., Wimo, A., Guerchet, M., Ali, G.-C., Wu, Y.-T., Prina, M., & Alzheimer’s Disease International. (2015). World Alzheimer Report 2015 The Global Impact of Dementia: An analysis of prevalence, incidence, cost and trends. https://www.alz.co.uk/research/WorldAlzheimerReport2015.pdf

Pusat Data dan Informasi Kementerian Kesehatan RI. (2017). Analisis Lansia di Indonesia.

Suriastini, Turana, Y., Sukadana, W., Sikoki, B., Witoelar, F., Lesmana, C. B. J., Mulyanto, E. D., Hermoko, R., & Anandari, G. A. A. A. (2018). Menggugah Lahirnya Kebijakan Kelanjutusiaan Menggugah Lahirnya Kebijakan Kelanjutusiaan.

Suriastini, Turana, Y., Witoelar, F., Supraptilah, B., Wicaksono, T., & Dwi, E. (2016). Policy Brief Angka Prevalensi Demensia: Perlu Perhatian Kita Semua. SurveyMETER, Maret, 1–4.

The Editors of Encyclopaedia Britannica. (2017). Java. Encyclopædia Britannica. https://www.britannica.com/place/Java-island-Indonesia

Yesufu, A. O. (2009). Demographic and modifiable risk factors for age related cognitive impairment and possible dementia. Loughborough: Loughborough University

In Jamaica, an embedded case-control designed study conducted by the Mona Ageing and Wellness Centre at the University of the West Indies, Mona, Jamaica, estimated the dementia prevalence in Jamaica to be at 5.9%, a comparable estimate with other countries in the region. When considering the distribution of dementia types found within the study conducted by Eldemire-Shearer et al. (2018), consistent with additional dementia literature, Alzheimer’s dementia accounted for the majority of the cases (Eldemire-Shearer et al., 2018 ).

References:

Eldemire-Shearer, D., James, K., Johnson, P., Gibson. R., Willie-Tyndale, D. (2018). Dementia among Older Persons in Jamaica: Prevalence and Policy Implications. West Indian Medical Journal, 2018; 67 (1): 1. Available from: https://www.mona.uwi.edu/fms/wimj/system/files/article_pdfs/wimj-iss1-2018_1_8.pdf

In 2016, the number of prevalent cases for dementia in Kenya was 61,120 and revealed a minor reduction of –2.1% (95% uncertainty Interval [UI] –2.8 to –1.5) from 1990 to 2016 (Nichols et al., 2019).

References:

Nichols, E., Szoeke, C. E. I., Vollset, S. E., Abbasi, N., Abd-Allah, F., Abdela, J., … Murray, C. J. L. (2019). Global, regional, and national burden of Alzheimer’s disease and other dementias, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016. The Lancet Neurology, 18(1), 88–106. http://doi.org/10.1016/S1474-4422(18)30403-4

Since 2003, two national health surveys and two dementia specific surveys have documented the prevalence of dementia and cognitive impairment in Mexico.

1. Mexican Health and Aging Study, MHAS (Encuesta Nacional de Salud y Envejecimiento en México, ENASEM, mhasweb.org).

The initiative is funded by the National Institute of Health and the National Institute of Aging of the United States. This is the first large scale longitudinal study in Mexico with data collected in 2001 (baseline study) with follow-up interviews in 2003, 2012, 2015 and 2018 (Wong et al., 2015). The objective of this longitudinal study is to prospectively evaluate the impact of diseases, functioning and mortality of adults 50 years of age and older (or adults born in 1951 or earlier at the time of the baseline survey), in more and less urban areas of Mexico. In MHAS, the identification of cases of dementia was made using an algorithm based on a cognitive evaluation (performed with a battery of instruments) and another on functional ability. The prevalence of dementia estimated in a report of 2011 was 5.2%, adjusted for age and schooling (Mejía-Arango et al., 2011).

2. National Health and Nutrition Survey ENSANUT 2012 (Encuesta Nacional de Salud y Nutrición, https://ensanut.insp.mx/).

The National Survey of Health and Nutrition (ENSANUT) is a probabilistic, multi-phase survey designed to estimate the prevalence of health conditions, nutrition, and its determinants, in nationally representative samples of children 0 to 11 years of age, adolescents 12 to 19 years old, adults 20 to 59, and older adults (60+ years). It has a representative sample design at the national, state, urban and rural stratum (Romero-Martinez et al., 2013). The module for the evaluation of older adults was first added in 2012 and included a sample of 8,874 adults aged 60 or older. Two instruments were used for dementia diagnosis: a battery to assess cognitive functioning (semantic verbal fluency the Mini-cog) and the evaluation of functional ability. These were used to construct a diagnostic algorithm. People who presented alteration in both cognitive ability and functional ability were considered to have dementia. This resulted in an estimated dementia prevalence of 7.9% for the total of older adults’ sample (Manrique Espinoza et al., 2013). In relation to distribution of dementia across the country, Acosta-Castillo et al., (2017) report the prevalence of dementia by state and level of deprivation, and report adjusted prevalence of dementia (by sex, age and education) of 8.0% at national level, ranging from 3.3% in Querétaro to 12.5% in Jalisco, and from 3.9% in people between 60-69 years and 20.6% in the group aged 80 years or more. The prevalence is similar in some levels of deprivation (around 8.0%), except in those areas with high and very high deprivation (11.1%). They report that of the almost 900,000 people living with dementia in Mexico, more than half have experienced food insecurity and about 200 thousand live in localities with high and very high levels of deprivation. This demonstrates great variability in the prevalence of dementia by state and suggests that many people affected by dementia experience high levels of vulnerability.

3. Dementia Research Group 10/66 study (https://www.alz.co.uk/1066/).

The 10/66 Dementia Research Group research programme was developed to address the dementia prevalence, incidence, and impact across Latin American countries, China and India, using a validated and common methodology in a multi-centric population of adults aged 65 years and over (Prina et al., 2017). Data have been obtained on the prevalence and impact of dementia, and on incidence (phase 2007-2010), which evaluated the incidence of dementia and some associated risk factors, as well as mortality, with a median follow-up of 3 years (Prince et al., 2012). The case identification of dementia is carried out using two algorithms, one that operationalizes the criteria for dementia of the DSM-IV, and another that is developed by the 10/66 group (Prince et al., 2003). A case is considered positive for dementia if either of the two criteria is positive. The prevalence of dementia is of 8.6% in the urban area, compared to 7.4 in the rural area. However, the standardised prevalence (95% CI) using the 10/66 algorithm is 7.4% (5.9-8.9) in Mexico in urban areas, and 7.3% (5.7-8.9) in rural areas. The standardised prevalence according to DSM-IV criteria is 3.2% (2.2-4.2) in Mexico urban, and 2.4% (1.2-3.6) (Llibre et al., 2008).

4. Survey of the Metropolitan Area of Guadalajara.

In 2014, a cross-sectional study was conducted on a population aged 60 years or above, living in the state of Jalisco (in the Western region of the country). A total of 1,142 people participated. Participants were selected through multiple probability random sampling and door-to-door interviewing. All participants were evaluated for their cognitive function, emotional state, and physical performance. Cognitive function, depression and functional disability were assessed using the Mini-Mental State Examination (Folstein et al., 1975), the geriatric depression scale and the Katz index, respectively. The diagnosis of dementia was made according to the DSM-IV criteria. The prevalence of dementia was 9.5% (63.35% of women and 36.7% of men) (Velázquez-Brizuela et al., 2014).

Table 11 shows prevalence data of dementia. Variations may be due to the use of different classifications, forms and extensions of cognitive assessments and assessment of limitations in functionality. For example, while ENSANUT and MHAS/ENASEM only assess dementia with cognition and loss of function (assessed through altered activities of daily living); in 1066 DSM-IV criteria are operationalised and the algorithm is tested against these criteria, not only against the sum of cognitive impairment and loss of functionality. 

Table 11. Population studies, prevalence data of dementia.

References:

Acosta-Castillo, G. I., Sosa-Ortiz, A. L., Manrique Espinoza, B. S., Salinas Rodriguez, A., & Juárez, M. de los Á. L. (2017). Prevalence of Dementia By State and Level of Marginalization in Mexico. Alzheimer’s & Dementia, 13(7), P512. https://doi.org/10.1016/j.jalz.2017.06.583

Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975). “Mini-mental state”. A practical method for grading the cognitive state of patients for the clinician. Journal of Psychiatric Research, 12(3), 189–198. https://doi.org/10.1016/0022-3956(75)90026-6

Llibre, J., Ferri, C. P., Acosta, D., Guerra, M., Huang, Y., Jacob, K. S., Krishnamoorthy, E. S., Salas, A., Sosa, A. L., Acosta, I., Dewey, M. E., Gaona, C., Jotheeswaran, A. T., Li, S., Rodriguez, D., Rodriguez, G., Kumar, P. S., Valhuerdi, A., & Prince, M. (2008). Prevalence of dementia in Latin America, India, and China: a population-based cross-sectional survey. The Lancet, 372(9637), 464–474. https://doi.org/10.1016/S0140-6736(08)61002-8

Manrique Espinoza, B., Salinas Rodríguez, A., Moreno Tamayo, K. M., Acosta Castillo, I., Sosa Ortiz, A. L., Gutiérrez Robledo, L. M., & Téllez Rojo, M. M. (2013). Health conditions and functional status of older adults in Mexico. Condiciones de salud y estado funcional de los adultos mayores en México. Salud Pública de México, 55(1), 323–331. https://doi.org/10.21149/spm.v55s2.5131

Mejía-Arango, S., Gutierrez, L. M., Minthon, L., Londos, E., Jo, L., Bostro, F., Larraya, F. P., Grasso, L., & Marí, G. (2011). Prevalence and Incidence Rates of Dementia and Cognitive Impairment No Dementia in the Mexican Population. International Journal of Geriatric Psychiatry, 23(7), 713–719. https://doi.org/10.1177/0898264311421199

Prina, A. M., Acosta, D., Acosta, I., Guerra, M., Huang, Y., Jotheeswaran, A. T., Jimenez-Velazquez, I. Z., Liu, Z., Llibre Rodriguez, J. J., Salas, A., Sosa, A. L., Williams, J. D., & Prince, M. (2017). Cohort Profile: The 10/66 study. International Journal of Epidemiology, 46(2), 406–406i. https://doi.org/10.1093/ije/dyw056

Prince, M., Acosta, D., Chiu, H., Scazufca, M., & Varghese, M. (2003). Dementia diagnosis in developing countries: a cross-cultural validation study. Lancet (London, England), 361(9361), 909–917. https://doi.org/10.1016/S0140-6736(03)12772-9

Prince, M., Acosta, D., Ferri, C. P., Guerra, M., Huang, Y., Rodriguez, J. J. L., Salas, A., Sosa, A. L., Williams, J. D., Dewey, M. E., Acosta, I., Jotheeswaran, A. T., & Liu, Z. (2012). Dementia incidence and mortality in middle-income countries, and associations with indicators of cognitive reserve: A 10/66 Dementia Research Group population-based cohort study. The Lancet, 380(9836), 50–58. https://doi.org/10.1016/S0140-6736(12)60399-7

Romero-Martínez, M., Shamah-Levy, T., Franco-Núñez, A., Villalpando, S., Cuevas-Nasu, L., Pablo Gutiérrez, J., & Rivera-Dommarco, J. (2013). Encuesta nacional de salud y nutrición 2012: diseño y cobertura. [National Health and Nutrition Survey 2012: design and coverage]. Salud Publica Mex, 55(2), S332-S340 (in Spanish). https://doi.org/10.21149/spm.v55s2.5132

Velázquez-Brizuela, I., Ortiz, G., Ventura-Castro, L., Árias-Merino, E., Pachecho-Moisés, F., & MA, M.-Islas. (2014). Prevalence of Dementia, Emotional State and Physical Performance among Older Adults in the Metropolitan Area of Guadalajara, Jalisco, Mexico. Current Gerontology and Geriatrics Research, 2014, 1–8. https://doi.org/10.1155/2014/387528

Wong, R., Michaels-Obregón, A., Palloni, A., Miguel Gutiérrez-Robledo, L., González-González, C., López-Ortega, M., María Téllez-Rojo, M., Mendoza-Alvarado, L. R., & Ts, L. (2015). Progression of aging in Mexico: the Mexican Health and Aging Study (MHAS) 2012 HHS Public Access. In Salud Publica Mex. https://researchexperts.utmb.edu/en/publications/progression-of-aging-in-mexico-the-mexican-health-and-aging-study

Prevalence rates reported by the Deloitte Access Economics report in 2017 (Deloitte Access Economics, 2017) are considered the best estimates for dementia prevalence in NZ. In the absence of NZ dementia prevalence studies, the Deloitte estimates are based on the Alzheimer’s Disease International (ADI) World Alzheimer’s report 2015 estimates for Australasia (Prince et al., 2015).

In turn, the ADI prevalence calculation for the population aged 60+ for Australasia was based on a systematic review and meta-analysis that identified four prevalence studies meeting the inclusion criteria – Gisborne 1980’s, Hobart 1980’s, Canberra 1990’s and a prevalence study on Indigenous Australians in the Kimberley region of Western Australia in 2008. The estimated prevalence for the <60 population was based on a 2003 study in Kensington/Chelsea in England.

These estimates were then used to calculate prevalence rates for the total NZ population as well as the 4 main ethnic groups in NZ – European, Māori, Pacific, and Asian – using age-gender relativities. The Deloitte report does comment “While there is evidence that the incidence of dementia may be higher for Māori and Pacific peoples in New Zealand, due to a higher prevalence of cardiovascular risk factors, no data were available to enable modelling of the extent of this difference.” 

Critique of the prevalence estimates for NZ

• The population sampled in studies used to estimate the Australasia dementia prevalence is not representative.
• Study location: Only one of the four studies used to calculate Australasia dementia prevalence was a NZ study and this was carried out in Gisborne in 1983.
• Ethnicity: Three of the studies did not provide a breakdown by ethnicity and the fourth was in an Indigenous Australian population that found a much higher prevalence in their population compared to the Australian population as a whole.
• Study year: Other than the indigenous Australian study in 2008, the remaining studies used in the prevalence calculation are 25-35 years old and even if the demographics are representative, other variables such as risk factors may not be representative of the current population.
• Prevalence calculations do not adjust for the differential risk factors for dementia between ethnicities in NZ.
• The Lancet commission on Dementia prevention and intervention in 2017 identified nine potentially modifiable risk factors for dementia, with each of the risk factors carrying a relative risk 1.4-1.9 times higher compared to those who did not have the risk factor.
• All these risk factors differentially affect Māori and PI ethnicities compared to Pakeha, and many of them increase the risk of dementia if they are present in midlife so there is an argument to be made that dementia prevalence is underestimated in these populations.

References:

Deloitte Access Economics. (2017). Dementia Economic Impact Report 2016. Available from: https://www2.deloitte.com/nz/en/pages/economics/articles/dementia-economic-impact-report-2016.html.

Prince, M., Wimo. A., Guerchet, M., Ali, G., Wu, Y., Prina, M. (2015). World Alzheimer’s report 2015: The Global Impact of Dementia: An analysis of prevalence, incidence, cost, and trends. London Alzheimer’s Disease International 2015. Available from: https://www.alzint.org/u/WorldAlzheimerReport2015.pdf.

The prevalence of dementia in Sub-Saharan Africa and South Africa has not been established conclusively (Kalaria et al., 2008; Kalula et al., 2010). From 2006 to 2050, South Africa’s older population is projected to increase from 3.3 to 6.4 million people (i.e., from 7% to 13% of the country’s population). The World Alzheimer’s report (2015) estimated that in 2015 about 186 000 people were living with dementia in South Africa, for which nearly 75% were women (Prince et al., 2016a). This number is expected to increase to 275 000 by 2030 (Prince et al., 2016a).

Although there are a few research studies on dementia in Sub-Saharan Africa, there is currently no nationally representative prevalence data available for South Africa (De Jager et al., 2017), with large scale community studies needed to confirm the prevalence of dementia (Ramlall et al., 2013). Existing research in South Africa has, for example, investigated the knowledge, attitudes, and beliefs about dementia in an urban Xhosa speaking community (Khonje et al., 2015), has examined the caregiving experiences for people with dementia (Gurayah, 2015; Pretorius et al., 2009), and has explored the consequences of stigma and related socio-cultural beliefs regarding people with dementia (Mkhonto & Hanssen, 2018).

Smaller studies have provided estimations of prevalence of dementia in South Africa. In 2010, a study examined all patients (N=305) at the UCT/Groote Schuur Hospital memory clinic between 2003 and 2008. The study evaluated the role and function of this facility in a resource-limited context and found that family members cared for 79% of patients (of which 74% lived with a spouse or an adult child), whereas 6% were institutionalised and 10% lived alone (Kalula et al., 2010). Depression was associated with 15% of patients and although Alzheimer’s disease was still the most common, when compared to other countries, vascular dementia (VaD) had a higher prevalence in South Africa (Kalula et al., 2010). This finding is suggestive of a high prevalence of stroke and associated risk factors that are not adequately addressed by the current health care systems (Kalula et al., 2010).

Working with the 10/66 Group, the University of the Free State examined an urban black community and reported a higher than expected 6% prevalence rate for persons 65 years and older (De Jager et al., 2015), while previous rates for Southern Africa have estimated 2.1% (Radebe, 2010). A smaller household study (N=100) in another urban, isiXhosa-speaking community in the Western Cape (Khayelitsha) found that 22% of households had a person over the age of 60 living in the area, of which 10% reported having more than one over the age of 60 (Khonje et al., 2015).

The first large screening study for dementia in South Africa was conducted in a low income, rural isiXhosa speaking population in the Amatole district, within the Eastern Cape province (De Jager et al., 2017). This community is characterised by subsistence farming of maize, with local diets supplemented with vegetables and occasional meat. A total of 1394 households were screened in 3 clinic catchment areas and estimated a prevalence of 11% for 65 years and older, indicating a higher than expected burden of dementia in South Africa, than the estimated 4% indicated by the World Alzheimer Report (2016) (De Jager et al., 2017). For those screened as dementia-positive participants, 69.8% were female and 69.8% had less than 7 years education. Dementia-positive participants were twice as likely to report any depressive symptoms and 17.1% of these reported on all 3 out of 3 (EURO-D questions) symptoms of depression.

References:

De Jager, C. A., Joska, J. A., Hoffman, M., Borochowitz, K. E., & Combrinck, M. I. (2015). Dementia in rural South Africa: A pressing need for epidemiological studies. South African Medical Journal, 105(3), 189–190. https://doi.org/10.7196/SAMJ.8904

De Jager, C.A., Msemburi, W., Pepper, K., & Combrinck, M. (2017). Dementia Prevalence in a Rural Region of South Africa: A Cross-Sectional Community Study. Journal of Alzheimer’s Disease, 60(3), 1087–1096. https://doi.org/10.3233/JAD-170325

Gurayah, T. (2015). Caregiving for people with dementia in a rural context in South Africa. South African Family Practice, 57(3), 194–197. https://doi.org/10.1080/20786190.2014.976946

Kalaria, R. N., Maestre, G. E., Arizaga, R., Friedland, R. P., Galasko, D., Hall, K., Luchsinger, J. A., Ogunniyi, A., Perry, E. K., Potocnik, F., Prince, M., Stewart, R., Wimo, A., Zhang, Z. X., & Antuono, P. (2008). Alzheimer’s disease and vascular dementia in developing countries: prevalence, management, and risk factors. The Lancet Neurology, 7(9), 812–826. https://doi.org/10.1016/S1474-4422(08)70169-8

Kalula, S. Z., Ferreira, M., Thomas, K. G. F., De Villiers, L., Joska, J. A., & Geffen, L. N. (2010). Profile and management of patients at a memory clinic. South African Medical Journal, 100(7), 449. https://doi.org/10.7196/SAMJ.3384

Khonje, V., Milligan, C., Yako, Y., Mabelane, M., Borochowitz, K. E., & Jager, C. A. De. (2015). Knowledge , Attitudes and Beliefs about Dementia in an Urban Xhosa-Speaking Community in South Africa. Advances in Alzheimer’s Disease, 4, 21–36. https://doi.org/10.4236/aad.2015.42004

Mkhonto, F., & Hanssen, I. (2018). When people with dementia are perceived as witches. Consequences for patients and nurse education in South Africa. Journal of Clinical Nursing, 27(1–2), e169–e176. https://doi.org/10.1111/jocn.13909

Pretorius, C., Walker, S., & Heyns, P. M. (2009). Sense of coherence amongst male caregivers in dementia: A South African perspective. Dementia, 8(1), 79–94. https://doi.org/10.1177/1471301208099046

Prince, Martin, Comas-Herrera, A., Knapp, M., Guerchet, M., & Karagiannidou, M. (2016a). World Alzheimer Report 2016: Improving healthcare for people living with dementia. In Alzheimer’s Disease International (ADI). https://doi.org/10.13140/RG.2.2.22580.04483

Ramlall, S., Chipps, J., Pillay, B., & Bhigjee, A. (2013). Mild cognitive impairment and dementia in a heterogeneous elderly population: Prevalence and risk profile. African Journal of Psychiatry (South Africa), 16(6), 456–465. https://doi.org/10.4314/ajpsy.v16i6.58