This is an advanced reading page for interested readers. The page does not provide information or suggestions relevant for day-to-day care of someone with dementia. If you are a caregiver looking for solutions, check our Caring for dementia patients menu. To know basics of dementia, start with What is Dementia.
Here is a selection of dementia and caregiving related reports and policy discussions, mainly from India, and also some major reports from outside India.
- The Dementia India Report 2010.
- Dementia India Strategy Report 2018
- Dementia in India 2020.
- Studies related to dementia prevalence, risk factors, and care interventions in India
A collection of links to online abstracts/ papers.
- Important, recent reports from other countries/ world-wide (Includes ADI’s useful collation for the COVID situation)..
The Dementia India Report 2010 was released on September 21, 2010, World Alzheimer’s Day. It can be downloaded from the ARDSI site Opens in new window. The links for the download is here: Full report (PDF file) Opens in new window.
For translations of the report:
- Kannada: The executive summary of the report has been translated into Kannada by NIMHANS. It can be downloaded/ viewed here: Kannada version, Dementia India Report 2010 (executive summary) (PDF file) Opens in new window. For more on this report, contact Dr. Girish Rao, NIMHANS, firstname.lastname@example.org
- Assamese: An Assamese version of the executive summary of the report is available from this page of the ARDSI Guwahati chapter (PDF file) Opens in new window.
ARDSI published a national strategy document after a series of region-wise national consultative meetings and presented this the Union Government in September 2018 and the the Hon. Health Minister Shri J P Nadda who received it gave a public assurance that the central government would soon come out with a country plan for dementia.
The submitted document can be viewed/ downloaded at ARDSI’s site at: Dementia India Strategy Report 2018 Opens in new window
Dementia in India 2020 was published by the Alzheimer’s and Related Disorders Society of India (ARDSI) Cochin Chapter, with academic support from Kerala University of Health Sciences (KUHS) Thrissur and released at the International Conference of Alzheimer’s Disease 2019, Cochin University of Science and Technology (CUSAT). With the permission of the editors, the report is available on this site and can be viewed at Dementia in India 2020 Opens in new window.
The document collects 14 chapters by various authors, edited by Dr CT Sudhir Kumar et al. (suggested citation is Kumar CTS, Shaji KS, Varghese M, Nair MKC (Eds) Dementia in India 2020.) The document includes collection of caregiver quotes and chapters on dementia assessment and diagnosis,Psychological and Behavioural Interventions in Dementia, Medical Management of Dementia, Dementia Prevalence in India, Dementia Care Costs in India, Legal and Ethical Issues in Dementia: Indian Scenario, Development of Community Resources for Dementia Care, Community Based Rehabilitation of People with Dementia: An Indian Experience, Caregiver Stress and interventions, Digital Interventions to Support Families, Dementia: Risk and Protective Factors, Experts’ and Stakeholders’ Consensus on Challenges and Priorities in Dementia, and National Dementia Strategy and Plan for India- the Roadmap.
- Dementia care during COVID related publication Experiences and needs of caregivers of persons with dementia in India during the COVID-19 pandemic – A Qualitative Study Opens in new window, Vaitheswaran S, Lakshminarayanan M, Ramanujam V, Sargunan S, Venkatesan S, Published in The American Journal of Geriatric Psychiatry, on July 06, 2020, DOI:https://doi.org/10.1016/j.jagp.2020.06.026
- Towards a dementia-friendly India Opens in new window, Kumar C T, George S, Kallivayalil RA. Indian J Psychol Med 2019;41:476-81
- Clinical practice guidelines for management of dementia Opens in new window, Shaji K S, Sivakumar P T, Rao G P, Paul N,. Indian J Psychiatry 2018;60, Suppl S3:312-28
- DEMENTIA FRIENDLY KERALA – THE WAY FORWARD Opens in new window, Sudhir Kumar CT1,Babu Varghese, Harish M Tharayil, Jacob Roy, Kerala Journal of Psychiatry, Vol. 28, No. 1 (2015)
- Dementia: Indian scenario Opens in new window, Das SK, Pal S, Ghosal MK. Dementia: Indian scenario. Neurol India [serial online] 2012 [cited 2018 Sep 23];60:618-24
- Bilingualism delays age at onset of dementia, independent of education and immigration status Opens in new window, Alladi S, Bak TH, Duggirala V, Surampudi B, Shailaja M, Shukla AK, Chaudri JR, Kaul S, Neurology November 26, 2013 vol. 81 no. 22, 1938-1944
- Caregiving: A Public Health Priority Opens in new window, Shaji KS, Reddy MS, Indian J Psychol Med , 2012;34: 303-5
- Incidence of Alzheimer’s disease in India: a 10 years follow-up study Opens in new window, Mathuranath PS, George A, Ranjith N, Justus S, Kumar MS, Menon R, Sarma PS, and Verghese J., Neurol India. 2012 Nov-Dec;60(6):625-30. doi: 10.4103/0028-3886.105198
- Dementia mortality: Estimates of survival after the onset of dementia range from 4 to 12 years [newwidow], Dr. Ravi Samuel, Indian J Psychiatry 2011;53:178-9
- Risk factors of dementia in North India: a case-control study Opens in new window, Tripathi M, Vibha D, Gupta P, Bhatia R, Padma Srivastava MV, Vivekanandhan S, Bhushan Singh M, Prasad K, Dergalust S, Mendez MF; Aging Ment Health. 2011 Jun 30
- Group intervention for carers of geriatric patients: experiences from a clinic in India Opens in new window, J. Henry, A. Jagannathan, K. Bhavana, B. Thomas, S. Bharath,M. Varghese, O. P. Jhirwal and P. T. Sivakumar; International Psychiatry, Volume 7 Number 2 April 2010
- Dementia care in developing countries: The road ahead Opens in new window by K S Shaji; Indian J Psychiatry 2009;51:5-7
- Behavioral symptoms and caregiver burden in dementia Opens in new window, Shaji KS, George RK, Prince MJ, Jacob KS; Indian J Psychiatry 2009;51:45-9
- The 10/66 dementia research group – 10 years on Opens in new window Martin J Prince, Indian Journal of Psychiatry, 2009, Vol 51, Issue 5, pages 8-15
- Family caregivers of people with dementia Opens in new window, Brodaty H, Donkin M; Dialogues Clin Neurosci. Jun 2009, 11(2): 217–228
- Closing the treatment gap for dementia in India Opens in new window, Dias A, Dewey ME, D’Souza J, Dhume R, Motghare DD, Shaji KS, Menon R, Prince M, Patel V., 2008 Jun 4; 3(6):e2333. Epub 2008 Jun 4.;53:178-9
- The Effectiveness of a Home Care Program for Supporting Caregivers of Persons with Dementia in Developing Countries: A Randomised Controlled Trial from Goa, India Opens in new window by Dias A, Dewey ME, D’Souza J, Dhume R, Motghare DD, et al. (2008) PLoS ONE 3(6): e2333. doi:10.1371/journal.pone.0002333s
- Usefulness of the Rowland Universal Dementia Assessment Scale in South India Opens in new window, T Iype, B K Ajitha, P Antony, N B Ajeeth, S Job, K S Shaji; J Neurol Neurosurg Psychiatry 2006;77:513-514 doi:10.1136/jnnp.2005.069005
- Global prevalence of dementia: a Delphi consensus study Opens in new window by Cleusa P Ferri, Prof Martin Prince, Prof Carol Brayne, and others; The Lancet, Volume 366, Issue 9503, Pages 2112 – 2117, 17 December 2005
- The impact associated with caring for a person with dementia: a report from the 10/66 Dementia Research Group’s Indian network Opens in new window by Amit Dias, Ravi Samuel, Vikram Patel, Martin Prince, R. Parameshwaran and E. S. Krishnamoorthy, Int J Geriatr Psychiatry 2004; 19: 182–184
- Care arrangements for people with dementia in developing countries Opens in new window by 10/66 Dementia Research Group, Int J Geriatr Psychiatry 2004; 19: 170–177.
- Sensitivity and Specificity of Cognitive and Functional Screening Instruments for Dementia: The Indo-U.S. Dementia Epidemiology Study Opens in new window by Rajesh Pandav, Gerda Fillenbaum, Graham Ratcliff D, Hiroko Dodge, Mary Ganguli MD; Journal of the American Geriatrics Society, Volume 50, Issue 3, pages 554–561, March 2002
- Revealing a hidden problem. An evaluation of a community dementia case-finding program from the Indian 10/66 dementia research network Opens in new window by Shaji, K. S., Arun Kishore, N. R., Lal, K. P. and Prince, M. (2002), International Journal of Geriatric Psychiatry, 17: 222–225. doi: 10.1002/gps.553
- Caregivers of people with Alzheimer’s disease: a qualitative study from the Indian 10/66 Dementia Research Network Opens in new window by Shaji, K. S., Smitha, K., Lal, K. P. and Prince, M. J., International Journal of Geriatric Psychiatry, 18: 1–6. doi: 10.1002/gps.649
Important, recent reports from other countries/ world-wide (Includes ADI’s useful collation for the COVID situation).
COVID and dementia
Alzheimer’s Disease International (ADI) has been making shared experiences of various countries in the COVID context available at its site and is regularly holding webinars and sharing suggestions through its page: ADI offers advice and support during COVID-19 Opens in new window. The page is kept up-to-date with information on the various webinars and other work done by ADI.
Risk Reduction related major publications
Dementia prevention, intervention, and care: 2020 report of the Lancet Commission: This Lancet report of 2020, published in Aug 2020, adds to the understanding of risk factors shared in the earlier 2017 report. The earlier report had identified modifiable factors as less education, hypertension, hearing impairment, smoking, obesity, depression, physical inactivity, diabetes, and low social contact. This report adds three more risk factors for dementia based on newer, convincing evidence. These factors are excessive alcohol consumption, traumatic brain injury, and air pollution.The report states that together the 12 modifiable risk factors account for around 40% of worldwide dementias, which consequently could theoretically be prevented or delayed. The potential for prevention is high and might be higher in low-income and middle-income countries (LMIC). Read the report (or download it) at Dementia prevention, intervention, and care: 2020 report of the Lancet Commission Opens in new window .
Risk reduction of cognitive decline and dementia: WHO Guidelines: In May 2019, World Health Organization (WHO) published a 96 page report with evidence-based recommendations on lifestyle behaviours and interventions to delay or prevent cognitive decline and dementia.This is intended as a tool for health care providers, governments, policy-makers and other stakeholders to strengthen their response to the dementia challenge. The report can be viewed/ downloaded from this page: Risk reduction of cognitive decline and dementia: WHO Guidelines Opens in new window .
Lancet Commissions: Dementia prevention, intervention, and care: The Lancet Commission on Dementia Prevention, Intervention, and Care has published a 62 page detailed report in July 2017, consolidating expert opinion on the emerging knowledge of how to prevent and manage dementia. This report includes the key messages of the commission as well as supporting discussions, data, and references. For this the Commission has looked at their understanding of the best evidence of how to prevent the preventable, treat the treatable, and care for both the person living with dementia and the carer. Their conclusions and process are documented in the report. The report can be viewed/ downloaded free by using a (free) subscriber account on the Lancet site, at Dementia prevention, intervention, and care Opens in new window (PDF file) .
Nutrition and dementia: A review of available research (ADI): In February 2014, Alzheimer’s Disease International (ADI) published a report that investigates the role of right nutrition in the life of persons with dementia. The report reviews dietary factors across the life course in terms of the risk of late onset dementia. It includes suggestions on nutrition-related actions. Read about it/ download it: Nutrition and dementia: A review of available research Opens in new window.
Also see World Alzheimer Report 2014, detailed in next section.
World Alzheimer Report, published yearly by Alzheimer’s Disease International
For the past few years, the Alzheimer’s Disease International has been publishing an annual World Alzheimer Report, each report focused on one important aspect and dealing with it in detail, combining research data, observations from across the world, and suggestions/ conclusions. Here are the reports published so far.
- The World Alzheimer Report 2020: ‘Design, Dignity, Dementia: dementia-related design and the built environment’ was released in September 2020. A large report (Volume 1 is 248 pages and Volume 2 is 264 pages), this looks at design progress to date, best practice, pioneers and innovators, design principles, application, regional and cultural contexts, including people with dementia in the design process, and design during the coronavirus pandemic and beyond. It includes 84 case studies. A webinar held at the launch, with interviews of many experts is available as a video recording and the slides used. See : World Alzheimer Report 2020: Design, Dignity, Dementia: dementia-related design and the built environment Opens in new window.
- The World Alzheimer Report 2019: ‘Attitudes to Dementia’ was released in September 2019. The report includes analysis of the findings of a survey of almost 70,000 people across 155 countries and territories, as well as expert essays and case studies from across the world. The survey spanned people living with dementia, carers, healthcare practitioners and the general public. Analysis of the study, which collected responses from, was carried out by the London School of Economics and Political Science (LSE).Read about it or download it here: The World Alzheimer Report 2019 Opens in new window.
- The World Alzheimer Report 2018: ‘The state of the art of dementia research: New frontiers’ was released in September 2018. Written by journalist Christina Patterson, it puts together interviews with multiple experts and stakeholders to look at research areas including basic science, diagnosis, drug discovery, risk reduction, and epidemiology and also features progress, innovation and developments in care research.Through this short report, Alzheimer’s Disease International (ADI) calls on governments to commit funds for dementia research. Read about it or download it here: The World Alzheimer Report 2018 Opens in new window.
- The World Alzheimer Report 2016: ‘The Global Impact of Dementia: Improving healthcare for people living with dementia’ was released in September 2016. It reviews research evidence on healthcare elements related to dementia care, and suggests ways to make it better and more efficient. The report suggests that the current over-specialised approach should be moved to an approach that balances specialized care with a more prominent role for primary and community care. This would increase capacity, reduce overall costs, and allow scaling of care. The suggested approach is discussed in detail. Read about it or download it here: The World Alzheimer Report 2016: Improving healthcare for people living with dementia: Coverage, quality and costs now and in the future Opens in new window.
- The World Alzheimer Report 2015: ‘The Global Impact of Dementia: An analysis of prevalence, incidence, cost and trends’ was released in August 2015. It provides updated data on dementia’s global prevalence, incidence and cost. It highlights the impact on low and middle income countries (LMICs), and includes information from India also. The report makes key recommendations for a global framework for action on dementia. It also reviews the evidence for and against recent trends in the prevalence and incidence of dementia over time. It also has an analysis of the broader societal impact of dementia. Read about it or download it here: The World Alzheimer Report 2015: ‘The Global Impact of Dementia: An analysis of prevalence, incidence, cost and trends’ Opens in new window.
- World Alzheimer Report 2014–Dementia and Risk Reduction: An analysis of protective and modifiable factors was published in 2014 as part of the year’s theme of the World Alzheimer’s Month (the theme was Dementia: Can we reduce the risk?). The report was reissued with minor corrections in October 2014. This report critically examines the evidence for the existence of modifiable risk factors for dementia. It focuses on sets of potential modifiable risk factors in four key domains, namely developmental, psychological and psychosocial, lifestyle and cardiovascular conditions. Recommendations for public health campaigns and disease prevention strategies are included. Read about the world report 2014 Opens in new window or download it: 2014 World Alzheimer Report (PDF file) Opens in new window.
- World Alzheimer’s Month 2013 – Dementia: a journey of caring. September 2013 was observed as the World Alzheimer’s Month. The theme was: Dementia: a journey of caring. This report was launched to coincide with World Alzheimer’s Month. Read about it/ download it The World Alzheimer Report 2013 – Journey of Caring: An analysis of long-term care for dementia Opens in new window.
- World Alzheimer Report 2012: Overcoming the stigma of dementia. This report was released by Alzheimer’s Disease International on 21 September 2012. It is based on a worldwide survey conducted with people with dementia and carers on their personal experiences of stigma. The report discusses stigma and dementia. It highlights best practices in the field of dementia, and includes recommendations. Check out more details and download links here: World Alzheimer Report 2012 Opens in new window.
- World Alzheimer Report 2011: Benefits of early diagnosis and prevention. This 2011 report shows that there are interventions that are effective in the early stages of dementia. Some of these may be more effective when started earlier. The report says that there is a strong economic argument in favor of earlier diagnosis and timely intervention. The key findings can be read at World Alzheimer Report 2011 Opens in new window; the page also offers download links: World Alzheimer Report 2011 executive summary (PDF file) Opens in new window and the World Alzheimer Report 2011 full report (PDF file) Opens in new window.
- World Alzheimer report 2010. Thisprovides a comprehensive global picture of the economic impact of Alzheimer’s disease and dementia. It includes estimates (worldwide, and for various regions) of the worldwide cost of dementia. Direct medical costs, direct non-medical costs and costs of informal (family) care are considered for this. Policy recommendations are included. Read about it/ download it: World Alzheimer report 2010 Opens in new window.
Various issues of Alzheimer’s Disease International’s Global Perspective
Every quarter or so, Alzheimer’s Disease International (ADI) publishes a newsletter, Global Perspective. This includes recognition for people with dementia and updates on work being done for dementia from many countries. See the full list or subscribe to the newsletter Opens in new window.
Dementia Innovation Readiness Index
A series of reports (2017, 2018 and 2020) have been published on ‘Dementia Innovation Readiness Index’ by the Global Coalition on Aging (GCOA) and ADI. The details of these can be seen at the ADI site at Dementia Innovation Readiness Index., which includes the download links. YOu can also visit the site of Global Coalition on Aging
The 2020 Report (Oct 2020), which also included the Lien Foundation as collaborator, focused on city-level innovation readiness to dementia in 30 major cities globally (includes Bangalore from India).
The 2018 report (July 2018) analyzed the readiness of countries to develop and deploy dementia solutions into their healthcare, policy and social frameworks for five countries: Argentina, Brazil, China, India, and Saudi Arabia – countries with younger populations than the G7 countries.
The 2017 report (April 2017) evaluated innovation in dementia treatment, prevention, and care across G7 countries.
Alzheimer’s Disease Facts and Figures (USA), annual reports from Alzheimer’s Association, USA
Every year, Alzheimer’s Association, USA, publishes a report on Alzheimer’s Disease Facts and Figures, where it covers topics like definitions, symptoms, types of dementia, diagnostic criteria, prevalence, mortality, impact on caregivers and cost to nation (USA), etc., and also includes some special focus topics (focus for that year).
Information from, and download links for the latest report (2019) can be seen at this link Opens in new window. Older reports were earlier available at the site, but have not been available after site reorganization (which began in June 2018 ) and it is not yet clear when and where the older reports will be made available. Please contact them if you want the older reports.
Women and Dementia: Some published reports
Some international reports have examined how dementia affects women and the various factors that are involved.
The Women & Dementia – A Global Challenge Opens in new window report was published in March 2017 by the Global Alzheimer’s & Dementia Action Alliance/ Alzheimer’s Society. It collates published research on the issue and highlights that the prevalence, care burden and stigma of dementia disproportionately affects women, making it a global women’s health, social care and rights challenge that can no longer be ignored. The report analyses existing national policy responses to the gendered challenges of dementia and outlines the international frameworks that can guide national dementia plans and initiatives to providing gender-appropriate responses.
The Women and Dementia: A global research review Opens in new window report was published in June 2015 by Alzheimer’s Disease International, and discusses the main issues affecting women in relation to dementia from an international perspective. It examines the effect of gender on three specific groups: women living with dementia; women caring for people with dementia in a professional caring role; women undertaking an informal caregiving role for someone with dementia.It focuses on cross-cutting issues, including factors affecting women in low and middle income countries (LMICs); family structures and kinship; and the effects of migration.
Important releases from WHO
Dementia: a public health priority (2012) by World Health Organization (WHO): The World Health Organization and Alzheimer’s Disease International published a report on dementia in 2012. Read about it and download it here: Dementia: a public health priority (PDF file) Opens in new window. This is a standard, much-quoted landmark report.
Thematic briefs for the First WHO Ministerial Conference on Global Action Against Dementia, March 2015: The World Health Organization (WHO) released four short, thematic briefs for the First WHO Ministerial Conference on Global Action Against Dementia, 16-17 March 2015. These thematic briefs are listed on the WHO page Opens in new window/ They can be downloaded: The epidemiology and impact of dementia: current state and future trends Opens in new window, Supporting informal caregivers of people living with dementia Opens in new window, Ensuring a human rights-based approach for people living with dementia Opens in new window, and Dementia: a public health priority Opens in new window.
Global burden of dementia and Various National Dementia Strategies/ Policies/ Plans: status, discussions, examples.
From Plan to Impact II (ADI): Alzheimer’s Disease International released a 62-page report, From Plan to Impact II: The urgent need for action (PDF file) Opens in new window in May 2019. This provides a status update on related to the the national dementia/ Alzheimer’s plans and policies of various nations.
Lancet: Global, regional, and national burden of Alzheimer’s disease and other dementias: In November, 2018, Lancet published the Global, regional, and national burden report for 1990–2016. This 19-page report aims to present the first detailed analysis of the global prevalence, mortality, and overall burden of dementia as captured by the Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2016, and to highlight the most important messages for clinicians and neurologists.The report can be viewed/ downloaded from the Lancet site, at 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 Opens in new window (PDF file) .
Alzheimer’s Disease International page for plans: ADI maintains a page at Government Alzheimer plans Opens in new window. Here it discusses the broad areas that national plans must address. It provides reports, reviews, and status updates related to the the national dementia/ Alzheimer’s plans and policies of various nations.
World Dementia Council: Statement of Purpose: The World Dementia Council has published a “Statement of Purpose” in May, 2014. View it here Dementia Council publishes statement of purpose Opens in new window.
The Global Impact of Dementia 2013-2050 (ADI): Alzheimer’s Disease International (ADI) has published a policy brief for heads of government. This brief updates the earlier published ADI’s prevalence figures. This brief was released ahead of the first G8 Dementia Summit held in December 2013. It includes data on the current and future impact of dementia world-wide. It also provides recommendations. Read about it/ download it Policy Brief: The Global Impact of Dementia 2013-2050 Opens in new window.
Some examples: National Dementia Strategy (England, Wales, Northern Ireland), National Plan to Address Alzheimer’s Disease(USA): Information about these national dementia strategies and related download links are available here: Information on National Dementia Strategies in England, Wales and Northern Ireland Opens in new window. USA has released a national plan for Alzheimer’s Disease and related disorders. Information on this plan and its various versions are this link (PDF download links also available): National Plans to Address Alzheimer’s Disease (USA) Opens in new window.
Dementia in the Asia Pacific Region (2014 report): Alzheimer’s Disease International published Dementia in the Asia Pacific Region in November 2014, the month when the Asia Pacific Regional Conference 2014 was held in New Delhi, India. This report gives some insight on of the social and economic impact of dementia across the countries of the Asia Pacific region. It includes updated estimates of dementia prevalence data for the region. For example, it tells us that the number of people with dementia in the region will increase from 23 million in 2015 to almost 71 million by 2050. Profiles of ADI member associations in this region are also included. Read the report: “Dementia in the Asia Pacific” Opens in new window or download it: Dementia in the Asia Pacific (PDF file) Opens in new window.
Dementia Friendly Communities (DFCs)
Alzheimer’s Disease International maintains resources on DFcs at Dementia Friendly Communities (DFCs) Opens in new window. The principles and a collection of initiatives are also available as reports in PDF format from this page.
10/66 PROJECT OF ADI
10/66 is an important project of Alzheimer’s Disease International, co-ordinated from the Institute of Psychiatry, Psychology and Neurosciences at King’s College London. The 10/66 Dementia Research Group carries out population-based research into dementia, non-communicable diseases and ageing in low and middle income countries. The site is here.
28th International Conference of ADI, April 2013, Taipei (Dementia: Action for Global Change): ADI partnered with TADA Chinese Taipei to host the 28th International Conference of Alzheimer’s Disease International in Taipei from 18 to 20 April 2013. The conference heading was Dementia: Action for Global Change. The presentations are available here: 28th International Conference of ADI Presentations Opens in new window.
New Diagnostic Criteria and Guidelines for Alzheimer’s Disease: In April 2011, new diagnostic criteria and guidelines for AD were released (27 years after the last release of such guidelines). Read this report on the release Opens in new window (the page includes an FAQ on the new guidelines, and has download links for the guidelines). These revised guidelines recognize three stages of AD. They propose biomarkers for preclinical Alzheimer’s Disease, Mild Cognitive Impairement (MCI), and Alzheimer’s Disease. Diagnostic criteria are provided for AD. All-cause dementia is also defined (not just AD).
The Nun Study is a longitudinal study of aging and Alzheimer’s disease. It is funded by the National Institute on Aging. Results from this study are considered very important in understanding how Alzheimer’s develops and grows, and how various persons show the symptoms. Read about the study here: The Nun Study Opens in new window