In the world's developing regions people are living longer, and having fewer children. High fat diets, smoking and sedentary lifestyles are becoming more common. Chronic non-communicable diseases (NCDs) linked to ageing – heart disease, stroke, cancer and dementia – are much more in evidence, and beginning to be recognized as a public health priority [1]. While cancer and heart disease contribute mainly to mortality, much of the burden of other NCDs (dementia, mental disorders, diabetes and stroke) arises instead from years lived with disability)[2]. Chronic disability, and the conditions that contribute to it have received comparatively little attention, in research, policy or practice.

Disability, as defined by the World Health Organization (WHO), refers to difficulties in carrying out an activity due to increased effort, discomfort or pain, slowness or changes in the way the activity is performed. Dependency, defined as 'the requirement for frequent help from other people, beyond what would be expected by virtue of family or social ties' [3] stems from disability, but disability may occur without dependency.

Estimates from the WHO Global Burden of Disease project (where both disability levels and needs for care were inferred from diagnoses) suggest that the total population prevalence of dependency is similar worldwide, varying only from 4.4% to 5.1% by region, and will increase only marginally by 2050 [4]. However, this overall stability masks a substantial shift in the profile of dependency, occurring mainly in low and middle income countries (LAMIC), and linked both to rapid demographic ageing and the health transition. The proportions of dependent persons who are aged 60 and over will increase between 2000 and 2050, from 21% to 30% in sub-Saharan Africa, from 23% to 44% in India, from 23% to 47% in Latin America, from 30% to 60% in China, and from 45% to 61% in developed countries [5]. Over this period numbers of dependent older people are forecast to quadruple in most LAMIC, while numbers of dependent younger people remain relatively stable. Therefore, in all world regions dependency is rapidly becoming a problem associated with ageing processes, particularly non-communicable disease morbidity.

Dependency is an important outcome for policy and practice. Dependent older people need care and support, which, typically, means a family member, friend or neighbour. This support may or may not be forthcoming. Caregivers can be tied to their role, with little or no respite. In developed countries caregiving is consistently associated with role strain and a high prevalence of anxiety and depression [6]. There is also accumulating evidence of adverse effects on caregiver health [7] including increased mortality [8]. 10/66 Dementia Research Group pilot studies in 24 LAMIC centres indicated that in the absence of formal support services dementia caregivers often have to cut back on paid work to care or face the costs of hiring paid help [9]. There are no compensatory benefits [9]. Since dependent older people often live in multigenerational households with their caregiver and their caregiver's children, caregiver psychological and financial strain could have wider negative impacts on, for example, child health and development, retention in education, and poverty prevention.

The 10/66 Dementia Research Group has conducted comprehensive population-based cross-sectional surveys of catchment areas in ten developing countries (India, China, Nigeria, Cuba, Brazil, Venezuela, Mexico, Peru, Argentina and the Dominican Republic) [10]. This new resource will allow us to estimate the prevalence of dependency, and the relative contribution of different NCDs to needs for care in the general older population. We are also now able to characterise care arrangements for people with dementia in representative population-based samples, comparing and contrasting these with those needing care in the context of other health conditions. This report focuses on a survey of five catchment area districts in Santo Domingo, the capital of the Dominican Republic.

The Dominican Republic shares the Caribbean island of Hispaniola with Haiti. The population is 9.4 million, and 0.5 million (5.7%) are aged 65 and over [11]. Life expectancy is 71 years for men and 75 for women. The Dominican Republic is one of the poorest of the 10/66 Latin American countries, with a per capita GDP (PPP) of US$ 9,200. In common with other countries in the region there are high levels of income inequality (a Gini index of 51.6). Forty two percent of the population live below the poverty line, one third of these in extreme poverty. Pension coverage, at only 18% of the economically active population, is one of the lowest in Latin America. Extensive reforms have been proposed, and are in the process of implementation. Community health care is provided by the government through the system of 'primary attention units'. Consultations are free, but medicines must be paid for. Despite low medical insurance coverage, private healthcare is widely used instead. The Dominican Republic has only twenty psychiatrists, twenty psychologists, and two neurologists per million population.

Study design and catchment area: A one-phase cross-sectional whole population catchment area survey in geographically defined districts in Santo Domingo. The survey protocol is described in detail in an open access publication [10]. Precision calculations indicated that an overall sample of 2,000 would allow estimation of a typical dementia prevalence of 2.5% with a precision of ± 0.9%. Atypical middle-class or high-income areas were avoided. The catchment areas selected were Villa Francisca, San Carlos, San Antón, Mejoramiento Social and Santa Barbara. After defining the boundaries, mapping was carried out to identify and locate households. Possible participants (inclusion criterion age 65 and over) were identified. Age was formally determined on revisit for the interview by comparing stated age according to participant and informant, and official records if available. Irreconcilable discrepancies of three or more years were settled using an event calendar approach. Participants were recruited following informed consent or on the basis of a relative's agreement in case of lack of capacity for consent due to dementia. Interviews were carried out in participants' own homes. All participants received the full assessment lasting approximately two to three hours. Ethical approval for the survey was provided by the research ethics committee for the Institute of Psychiatry, King's College London, and the Bioethics National Committee for Research in the Dominican Republic.

Surprisingly, this seems to be the first comprehensive, population-based study of dependency, and consequent care arrangements conducted in a low or middle income country. In Santo Domingo, 7.1% of the older population (aged 65 years or older) required much care and a further 4.7% required at least some care. The prevalence of dependency increased sharply with increasing age, with the more marked dependency needs being concentrated among those aged 80 years and over. Income insecurity was prominent among dependent older people, who were less likely to be in receipt of a pension and much less likely to work, but no more likely to receive financial support from their family. Needing much care was strongly associated with comorbidity between cognitive, psychological and physical health problems. However, dementia made the strongest independent contribution to needing much care, with a population attributable prevalence fraction of 0.44. Among those needing care, those with dementia stood out as being more disabled, as needing more care (particularly support with core activities of daily living), and as being more likely to need the additional support of a paid caregiver. Carers of those with dementia experienced more role strain than did carers of those with other underlying health conditions.

The strengths of our study are that we applied a one-phase survey methodology on a large representative sample of older adults, achieving a good response rate for a broad based assessment of health status (including cognitive, mental and physical disorders, global health and disability), social, demographic and economic circumstances. A suitable informant was interviewed for every participant to ascertain needs for care directly (as opposed to merely inferring this from participant reports of limitations in activities of daily living). In the event of the participant being identified as a care recipient, we obtained further detailed information on the care arrangements, and any consequent strain experienced by the caregiver. The main weakness is that dependency was ascertained using a semi-structured interview. The rating of level of dependency (some care versus much care) was somewhat subjective. This was intentional, given the difficulties of developing a more structured approach that would have had equal validity across many different countries and cultures. Nevertheless, data on inter-rater reliability would have been valuable. Also, dementia and depression were diagnosed on the basis of extensive structured clinical interviews whereas stroke and other physical impairments were assessed only on the basis of self-report. Therefore, there may have been greater misclassification of the physical health outcomes, possibly leading to an underestimation of their contribution to dependency. Conversely we did not specify, when screening for dependency, that care could include prompting, remembering and supervising, in addition to physical care. This might have led to an underestimation of the contribution of dementia to dependency.

Our estimate, of 11.8% of participants with dependency needs is a little lower than that from population-based surveys of those aged 65 and over from England and Wales [26] (15.7% with significant disability among whom 86% had dependency needs), Scotland [27] (15% with short interval dependency), Spain [28] (15.5% with dependency in one or more of seven ADLs), France [29] (12.4% confined to home or bed) and the USA National Long Term Care surveys [30] (17.1% disabled in one or more activities of daily living, or living in a care home). Proper comparison would require age adjustment. Only the last of these studies provides age-specific prevalence estimates (65–74 8.4%; 75–84 21.4%; 85 and over 52.7%). Applying these prevalences to the age structure of our sample gives 377.5 expected cases of dependency versus the 237 that we observed, a standardised morbidity ratio of 62.8.

People with dementia (often comorbid with other health conditions) accounted for more than half of those needing much care, and a quarter of those needing some care. Our findings regarding the particular character of the experiences linked to caring for an older person with dementia are consistent with the only comparable findings from a population based survey, that of more than 1,500 family caregivers interviewed in the 1996 USA National Caregiver Survey [31]. In the USA, dementia caregivers spent longer providing care, reported more impacts on their employment, more caregiver strain, more mental and physical health problems, less time for leisure and more family conflict. Unfortunately, dementia, which has a uniquely devastating impact on capacity for independent living is often forgotten when policies for prevention and management of NCDs are proposed, as for example with the recent Lancet Series on non-communicable diseases [32], and the WHO's Global Report on Innovative Care for Chronic Conditions [33]. An original finding from our analysis is that the effect of dementia upon caregiver strain is entirely mediated by the severity of behavioural and psychological symptoms. Furthermore the independent predictive power of these symptoms (19.6% of the variance in caregiver strain explained) was much greater than that of dementia (6.9% of the variance). Although often referred to as behavioural and psychological symptoms of dementia (BPSD) these features (psychological symptoms – delusions, hallucinations, depression/dysphoria, anxiety, elation/euphoria; behavioural symptoms – apathy, disinhibition, agitation/aggression, motor, sleep and appetite disturbance) are not condition specific [24, 34].

LAMIC governments will face many challenges in the near future as numbers of dependent older people increase rapidly. An adequate response will require

a) policies to prevent disability through the control of NCDs,

b) policies to limit disability through more active community-based rehabilitation,

c) policies to manage disability and dependency through improved access to age-appropriate long-term support and care.

Such measures are already strongly advocated through international agreements including the Madrid International Plan on Action on Ageing (2002) and the UN Convention on the Rights of People with Disabilities (2007). A recent WHO report on long-term care policy [35] noted wide international variation in the apportioning of responsibilities between families and the state, but proposed that all countries could and should determine transparently the assistance needed by older people and their carers, and the eligibility for and financing of long-term care support. In practice, LAMIC governments have avoided providing or financing long-term care [36], and few if any have comprehensive policies and plans.

Primary health care services in LAMIC tend to fail older people with dementia, [36–39] as they focus on acute 'treatable' conditions and are clinic-based. There is a need for a paradigm shift beyond simple curative interventions to encompass long-term regular support, community outreach and domiciliary care, family involvement and multisectoral working. The WHO have proposed an alternative care framework (Innovative Care for Chronic Conditions)[33] that addresses many of these issues. ICCC is likely to be as applicable to dementia care as to other chronic NCDs – mental disorders, stroke, heart disease and diabetes – for which it was initially proposed. 10/66 is currently testing the effectiveness of training community healthcare workers to identify people with dementia [40–42], and to deliver a brief intervention to educate and train caregivers [10]. In practice, such interventions will need to be incorporated into horizontally constructed programs addressing the generic needs of frail, dependent older people and their caregivers, whether arising from cognitive, mental or physical disorders. One focus should perhaps be upon the assessment and syndromal management of the behavioural and psychological problems that, our research suggests, contribute so much to caregiver strain.

A key finding from our analysis is the economic disadvantage experienced by older dependent persons and the families that care for them. For older people in developing countries 'dependency anxiety' [37, 43, 44] – not wanting to be a burden on relatives, fearing inadequate support, and therefore wishing to maintain independence from the family – is a key motivating principle. The Nobel Prize winning economist Joseph Stiglitz commented:

'There is no subject of greater importance than the ageing of the population and the provision of social protection for older people. It affects the very nature of our societies and concerns not only older people, but all sections of the population.' [45].

Some LAMIC governments have sought to encourage or coerce families to shoulder this responsibility [36]. For example, the Indian parliament passed a law to this effect in 2007. Such policies seem destined to fail in the longer-term. Inexorable trends towards more internal and international migration, declining fertility, higher levels of education and increased participation of women in the workforce will reduce the availability and willingness of children (principally daughters and daughters-in-law) to care [36]. Social pensions provide insurance against the risks that older people face, including uncertainty over how long they will live, how long they will remain healthy, whether they can count upon the support of others if they need it, and how long they can earn an income. Furthermore, in rural Brazil, they have been shown to support whole families [46], reducing the risk of household poverty [47], and have even been linked to increased school enrolment, particularly of teenage girls [45]. Most importantly they reinforce reciprocal family ties, changing the perspective from one in which older people are seen as a dependent drain upon household resources to one in which they can be properly valued for their non-economic as well as their economic contributions. Dependent older people would be particularly likely to benefit – informal care would be bolstered and formal/paid care would be more affordable.