The Characteristics and Outcomes of People with Dementia in Inpatient Mental Health Care: A Review

References

• Aartsma, D. P., Groenewald, E., Koen, L., Potocnik, F., & Niehaus, D. (2019). A clinical profile of inpatient admissions to the psychogeriatric unit at Stikland hospital. South African Journal of Psychiatry, 25(1), 1–5. doi:10.4102/sajpsychiatry.v25i0.1344
   Google Scholar
• Akpaffiong, M., Kunik, M. E., Hale, D., Molinari, V., & Orengo, C. (1999). Cross‐cultural differences in demented geropsychiatric inpatients with behavioral disturbances. International Journal of Geriatric Psychiatry, 14(10), 845–850. doi:10.1002/(SICI)1099-1166(199910)14:10<845::AID-GPS34>3.0.CO;2-H
   PubMed Web of Science ®Google Scholar
• Alanen, H.-M., Pitkänen, A., Suontaka-Jamalainen, K., Kampman, O., & Leinonen, E. (2015). Acute psychogeriatric inpatient treatment improves neuropsychiatric symptoms but impairs the level of functioning in patients with dementia. Dementia and Geriatric Cognitive Disorders, 40(5–6), 290–296. doi:10.1159/000431087
   PubMed Web of Science ®Google Scholar
• Alzheimer’s Disease International. (2016). World alzheimer report 2016: Improving healthcare for people living with dementia.
   Google Scholar
• Alzheimer’s Society. (2011). Optimising treatment and care for people with behavioural and psychological symptoms of dementia. A best practice guide for health and social care professionals. A. s. Society. https://www.alzheimers.org.uk/sites/default/files/2018-08/Optimising%20treatment%20and%20care%20-%20best%20practice%20guide.pdf?downloadID=609
   Google Scholar
• Alzheimer’s Society. (2016). Fix dementia care: Hospitals https://www.alzheimers.org.uk/sites/default/files/migrate/downloads/fix_dementia_care_-_hospitals.pdf
   Google Scholar
• Astell, A. J., Clark, S. A., & Hartley, N. T. (2008). Predictors of discharge destination for 234 patients admitted to a combined geriatric medicine/old age psychiatry unit. International Journal of Geriatric Psychiatry: A Journal of the Psychiatry of Late Life and Allied Sciences, 23(9), 903–908. doi:10.1002/gps.2002
   Google Scholar
• Aziz, V. M., Hill, N., & Kumar, S. (2018). Completed audit cycle to explore the use of the STOPP/START toolkit to optimise medication in psychiatric in-patients with dementia. BJPsych Bulletin, 42(1), 37–41. doi:10.1192/bjb.2017.10
   PubMed Web of Science ®Google Scholar
• Ballard, C., Corbett, A., Orrell, M., Williams, G., Moniz-Cook, E., Romeo, R., … Woodward-Carlton, B. (2018). Impact of person-centred care training and person-centred activities on quality of life, agitation, and antipsychotic use in people with dementia living in nursing homes: A cluster-randomised controlled trial. PLoS medicine, 15(2), e1002500. doi:10.1371/journal.pmed.1002500
   PubMed Web of Science ®Google Scholar
• Barnes, T. R., Banerjee, S., Collins, N., Treloar, A., McIntyre, S. M., & Paton, C. (2012). Antipsychotics in dementia: Prevalence and quality of antipsychotic drug prescribing in UK mental health services. The British Journal of Psychiatry, 201(3), 221–226. doi:10.1192/bjp.bp.111.107631
   PubMed Web of Science ®Google Scholar
• Black, W., & Almeida, O. P. (2004). A systematic review of the association between the behavioral and psychological symptoms of dementia and burden of care. International Psychogeriatrics, 16(3), 295–315. doi:10.1017/S1041610204000468
   PubMed Web of Science ®Google Scholar
• Brackenridge, P., Courtnay, K., Jha, A., & Lawrence, R. (1997). Does hospital admission affect dependency levels of elderly psychiatric patients? International Journal of Geriatric Psychiatry, 12(7), 750–752. doi:10.1002/(SICI)1099-1166(199707)12:7<750::AID-GPS627>3.0.CO;2-O
   PubMed Web of Science ®Google Scholar
• Bucher, C. O., Dubuc, N., von Gunten, A., Trottier, L., & Morin, D. (2016). Development and validation of clinical profiles of patients hospitalized due to behavioral and psychological symptoms of dementia. BMC Psychiatry, 16(1), 1–12. doi:10.1186/s12888-015-0706-4
   PubMedGoogle Scholar
• Burton, M. C., Warren, M., Cha, S. S., Stevens, M., Blommer, M., Kung, S., & Lapid, M. I. (2016). Identifying patients in the acute psychiatric hospital who may benefit from a palliative care approach. American Journal of Hospice and Palliative Medicine®, 33(3), 228–232. doi:10.1177/1049909114554795
   PubMed Web of Science ®Google Scholar
• Chan, S. S., Chiu, H. F., Lam, L. C., & Leung, V. P. (2002). Prevalence of dementia with Lewy bodies in an inpatient psychogeriatric population in Hong Kong Chinese. International Journal of Geriatric Psychiatry, 17(9), 847–850. doi:10.1002/gps.716
   PubMed Web of Science ®Google Scholar
• Chan, V. T., Woo, B. K., Sewell, D. D., Allen, E. C., Golshan, S., Rice, V., … Daly, J. W. (2009). Reduction of suboptimal prescribing and clinical outcome for dementia patients in a senior behavioral health inpatient unit. International Psychogeriatrics, 21(1), 195–199. doi:10.1017/S104161020800803X
   PubMed Web of Science ®Google Scholar
• Cohen-Mansfield, J., Marx, M. S., & Rosenthal, A. S. (1989). A description of agitation in a nursing home. Journal of Gerontology, 44(3), M77–M84. doi:10.1093/geronj/44.3.M77
   PubMedGoogle Scholar
• Cummings, J. L., Mega, M., Gray, K., Rosenberg-Thompson, S., Carusi, D. A., & Gornbein, J. (1994). The neuropsychiatric inventory: Comprehensive assessment of psychopathology in dementia. Neurology, 44(12), 2308. doi:10.1212/WNL.44.12.2308
   PubMed Web of Science ®Google Scholar
• Davis, P. S., Holman, C. D. A. J., & Brameld, K. (2000). Gender differences in survival of 234 patients referred to a psychogeriatric service. International Journal of Geriatric Psychiatry, 15(11), 1061–1069. doi:10.1002/1099-1166(200011)15:11<1061::AID-GPS280>3.0.CO;2-9
   PubMed Web of Science ®Google Scholar
• de Vugt, M. E., Stevens, F., Aalten, P., Lousberg, R., Jaspers, N., & Verhey, F. R. (2005). A prospective study of the effects of behavioral symptoms on the institutionalization of patients with dementia. International Psychogeriatrics, 17(4), 577–589. doi:10.1017/S1041610205002292
   PubMed Web of Science ®Google Scholar
• Djernes, J. K., Gulmann, N. C., Abelskov, K. E., Juul-Nielsen, S., & Sørensen, L. (1998). Psychopathologic and functional outcome in the treatment of elderly inpatients with depressive disorders, dementia, delirium, and psychoses. International Psychogeriatrics, 10(1), 71–83. doi:10.1017/S104161029800516X
   PubMedGoogle Scholar
• Edmans, B. G., Wolverson, E., Dunning, R., Slann, M., Russell, G., Crowther, G., … Underwood, B. R. (2021). Inpatient psychiatric care for patients with dementia at four sites in the United Kingdom. International Journal of Geriatric Psychiatry, 37(2), 1-4.
   PubMed Web of Science ®Google Scholar
• Ekiz, E., Videler, A. C., & Van Alphen, S. P. (2020). Feasibility of the cognitive model for behavioral interventions in older adults with behavioral and psychological symptoms of dementia. Clinical Gerontologist, 45(4), 1–12.
   PubMed Web of Science ®Google Scholar
• Folstein, M. F., Robins, L. N., & Helzer, J. E. (1983). The mini-mental state examination. Archives of General Psychiatry, 40(7), 812. doi:10.1001/archpsyc.1983.01790060110016
   PubMed Web of Science ®Google Scholar
• Freyne, A., & Wrigley, M. (1997). Acute inpatient admissions in a community oriented old age psychiatry service. Irish Journal of Psychological Medicine, 14(1), 4–7. doi:10.1017/S0790966700002810
   Web of Science ®Google Scholar
• Goldberg, S. E., Bradshaw, L. E., Kearney, F. C., Russell, C., Whittamore, K. H., Foster, P. E., … Lewis, S. A. (2013). Care in specialist medical and mental health unit compared with standard care for older people with cognitive impairment admitted to general hospital: Randomised controlled trial (NIHR TEAM trial). Bmj, 347(jul02 1), f4132–f4132. doi:10.1136/bmj.f4132
   PubMedGoogle Scholar
• Gondhalekar, M. R., Bakkar, A., Chaplin, R., Parker, E., & Low, R. (2021). Organic versus mixed specialist older adult inpatient mental health units for people with dementia. Nursing Older People, 33(4). https://journals.rcni.com/nursing-older-people/evidence-and-practice/organic-versus-mixed-specialist-older-adult-inpatient-mental-health-units-for-people-with-dementia-nop.2021.e1353/abs
   Google Scholar
• Handley, M., Bunn, F., & Goodman, C. (2017). Dementia-friendly interventions to improve the care of people living with dementia admitted to hospitals: A realist review. BMJ open, 7(7), e015257. doi:10.1136/bmjopen-2016-015257
   PubMed Web of Science ®Google Scholar
• Harrison, A. W., Kernutt, G. J., & Piperoglou, M. V. (1988). A survey of patients in a regional geriatric psychiatry inpatient unit. Australian & New Zealand Journal of Psychiatry, 22(4), 412–417. doi:10.3109/00048678809161350
   PubMed Web of Science ®Google Scholar
• Hassett, A., George, K., & Harrigan, S. (1999). Admissions of elderly patients from English-speaking and non-English-speaking backgrounds to an inpatient psychogeriatric unit. Australian & New Zealand Journal of Psychiatry, 33(4), 576–582. doi:10.1080/j.1440-1614.1999.00537.x
   PubMed Web of Science ®Google Scholar
• Haw, C., Stoffels, M., Purkayastha, D. D., & Sudad, S. (2015). Antipsychotics for behavioral and psychiatric symptoms of dementia: A reaudit in a specialist inpatient service. International Psychogeriatrics, 27(1), 171–172. doi:10.1017/S1041610214001288
   PubMed Web of Science ®Google Scholar
• Ismail, Z., Arenovich, T., Granger, R., Grieve, C., Willett, P., Patten, S., & Mulsant, B. H. (2015). Associations of medical comorbidity, psychosis, pain, and capacity with psychiatric hospital length of stay in geriatric inpatients with and without dementia. International Psychogeriatrics, 27(2), 313–321. doi:10.1017/S1041610214002002
   Web of Science ®Google Scholar
• James, I., & Moniz-Cook, E. (2018). Evidence briefing: Behaviour that challenges in dementia. British Psychological Society. www.bps.org.uk
   Google Scholar
• Kales, H. C., Gitlin, L. N., & Lyketsos, C. G.; Assessment t. D. E. P. o. t., & Dementia, M. o. t. N. S. o. (2014). Management of neuropsychiatric symptoms of dementia in clinical settings: Recommendations from a multidisciplinary expert panel. Journal of the American Geriatrics Society, 62(4), 762–769.
   PubMed Web of Science ®Google Scholar
• Karrer, M., Schnelli, A., Zeller, A., & Mayer, H. (2021). A systematic review of interventions to improve acute hospital care for people with dementia. Geriatric Nursing, 42(3), 657–673. doi:10.1016/j.gerinurse.2021.03.006
   PubMed Web of Science ®Google Scholar
• Koskas, P., Feugeas, M. C. H., Saad, S., Belqadi, S., Daraux, J., & Drunat, O. (2011). Management of behavioral and psychological symptoms of dementia in a dedicated psychogeriatric unit: A pilot experience. Alzheimer Disease & Associated Disorders, 25(2), 184–186. doi:10.1097/WAD.0b013e3181fa2f81
   PubMed Web of Science ®Google Scholar
• Lewis, L., Pennypaker, L., Simpson, W., Bachman, D., Wohlreich, G., Meeks, A., … Sampson, R. (1993). Behavioral intensive care unit (BICU): A new concept in the management of acute agitated behavior in elderly demented patients. The Gerontologist, 33(6), 801–806. doi:10.1093/geront/33.6.801
   PubMed Web of Science ®Google Scholar
• Livingston, G., Rostamipour, H., Gallagher, P., Kalafatis, C., Shastri, A., Huzzey, L., … Marston, L. (2020). Prevalence, management, and outcomes of SARS-CoV-2 infections in older people and those with dementia in mental health wards in London, UK: A retrospective observational study. The Lancet Psychiatry, 7(12), 1054–1063. doi:10.1016/S2215-0366(20)30434-X
   PubMed Web of Science ®Google Scholar
• Manu, P., Grudnikoff, E., Khan, S., Kremen, N. J., Greenwald, B. S., Kane, J. M., & Correll, C. U. (2013). Medical outcome of patients with dementia in a free-standing psychiatric hospital. Journal of Geriatric Psychiatry and Neurology, 26(1), 29–33. doi:10.1177/0891988712473799
   PubMed Web of Science ®Google Scholar
• McCausland, B., Patel, H., Amin, J., Baldwin, D., Loughran, K., & Osman-Hicks, V. (2019). A systematic review of specialist inpatient dementia care services versus standard inpatient dementia care in acute hospitals. Aging Clinical and Experimental Research, 31(5), 595–610. doi:10.1007/s40520-018-1021-y
   PubMed Web of Science ®Google Scholar
• McMinn, B. G., & Hinton, L. (2000). Confined to barracks: The effects of indoor confinement on aggressive behavior among inpatients of an acute psychogeriatric unit. American Journal of Alzheimer’s Disease, 15(1), 36–41. doi:10.1177/153331750001500106
   Google Scholar
• Mei-Tal, V., & Meyers, B. S. (1986). Empirical study on an inpatient psychogeriatric unit: Diagnostic complexities. The International Journal of Psychiatry in Medicine, 15(2), 91–109. doi:10.2190/APUG-89N0-X5F6-6032
   Web of Science ®Google Scholar
• Moniz-Cook, E., Hart, C., Woods, R., Whitaker, C., James, I., Russell, I., … Campion, P. (2017). Challenge demcare: Management of challenging behaviour in dementia at home and in care homes–development, evaluation and implementation of an online individualised intervention for care homes; and a cohort study of specialist community mental health care for families. Programme Grants for Applied Research, 5(15). https://www.journalslibrary.nihr.ac.uk/pgfar/pgfar05150/#/abstract
   Google Scholar
• Morris, J. C. (1997). Clinical dementia rating: A reliable and valid diagnostic and staging measure for dementia of the alzheimer type. International Psychogeriatrics, 9(S1), 173–176. doi:10.1017/S1041610297004870
   PubMedGoogle Scholar
• Moss, F., Wilson, B., Harrigan, S., & Ames, D. (1995). Psychiatric diagnoses, outcomes and lengths of stay of patients admitted to an acute psychogeriatric unit. International Journal of Geriatric Psychiatry, 10(10), 849–854. doi:10.1002/gps.930101006
   Web of Science ®Google Scholar
• Nahas, Z., Kunik, M. E., Orengo, C. A., Molinari, V., & Workman, R. (1997). Depression in male geropsychiatric inpatients with and without dementia: A naturalistic study. Journal of Affective Disorders, 46(3), 243–246. doi:10.1016/S0165-0327(97)01430-4
   PubMed Web of Science ®Google Scholar
• National Institue for Health and Care Excellence. (2019). Dementia quality standard [QS184] https://www.nice.org.uk/guidance/qs184
   Google Scholar
• National Institute for Health and Clinical Excellence. (2018). Dementia: Assessment, management and support for people living with dementia and their carers. www.nice.org.uk/guidance/ng97
   Google Scholar
• National Institute for Health Research. (2019). Improving care by using patient feedback
   Google Scholar
• National Institute of Health and Clinical Excellence. (2016). Dementia: Supporting people with dementia and their carers in health and social care
   Google Scholar
• Neville, P., Boyle, A., & Baillon, S. (1999). A descriptive survey of acute bed usage for dementia care in old age psychiatry. International Journal of Geriatric Psychiatry, 14(5), 348–354. doi:10.1002/(SICI)1099-1166(199905)14:5<348::AID-GPS915>3.0.CO;2-B
   PubMed Web of Science ®Google Scholar
• Nirodi, P., & Mitchell, A. (2002). The quality of psychotropic drug prescribing in patients in psychiatric units for the elderly. Aging & mental health, 6(2), 191–196. doi:10.1080/13607860220126817
   PubMed Web of Science ®Google Scholar
• O’Connor, D. W., D’Cunha, C., Clifton, T., Huppert, D., Lowy, H., Macfarlane, S., … Tsanglis, M. (2018). Quality indicators of psychotropic prescribing to people with dementia in aged psychiatry inpatient units. Aging & mental health, 22(11), 1432–1437. doi:10.1080/13607863.2017.1366418
   PubMed Web of Science ®Google Scholar
• O’Mahony, D., O’Sullivan, D., Byrne, S., O’Connor, M. N., Ryan, C., & Gallagher, P. (2014). STOPP/START criteria for potentially inappropriate prescribing in older people: Version 2. Age and Ageing, 44(2), 213–218. doi:10.1093/ageing/afu145
   PubMed Web of Science ®Google Scholar
• Palmstierna, T., & Wistedt, B. (1987). Staff observation aggression scale, SOAS: Presentation and evaluation. Acta Psychiatrica Scandinavica, 76(6), 657–663. doi:10.1111/j.1600-0447.1987.tb02936.x
   PubMed Web of Science ®Google Scholar
• Paschali, M., Kamp, D., Reichmann, C., Jaenner, M., Lange-Asschenfeldt, C., & Supprian, T. (2018). A systematic evaluation of impulsive–aggressive behavior in psychogeriatric inpatients using the staff observation aggression scale-revision (SOAS-R). International Psychogeriatrics, 30(1), 61–68. doi:10.1017/S1041610217001600
   PubMed Web of Science ®Google Scholar
• Patrick, C., Donaldson, A., & Short, L. (2020). Letter to Golüke et al in response to” Risk factors of mortality in older patients with dementia in psychiatric care”. International Journal of Geriatric Psychiatry, 35(9), 1079–1080. doi:10.1002/gps.5338
   PubMed Web of Science ®Google Scholar
• Patterson, T., & Compton, S. (1989). Mortality rates of patients admitted to a psychogeriatric assessment unit. The Ulster Medical Journal, 58(2), 134.
   PubMedGoogle Scholar
• Pinner, G., Hiller, J., Branton, T., & Ramakrishnan, A. (2011). In-patient care for older people within mental health services. London: Royal College of Psychiatry.
   Google Scholar
• Pitkänen, A., Alanen, H.-M., Kampman, O., & Leinonen, E. (2018). Outcome of neuropsychiatric symptoms and daily functioning of patients with dementia treated on an acute psychogeriatric ward. Nordic Journal of Psychiatry, 72(7), 521–525. doi:10.1080/08039488.2018.1532021
   PubMed Web of Science ®Google Scholar
• Pongan, E., Freulon, M., Delphin-Combe, F., Dibie-Racoupeau, F., Martin-Gaujard, G., Federico, D., … Fabre, F. (2014). Initial and long-term evaluation of patients with alzheimer’s after hospitalization in cognitive and behavioural units: The EVITAL study design. BMC Psychiatry, 14(1), 1–6. doi:10.1186/s12888-014-0308-6
   Google Scholar
• Pongan, E., Dorey, J.-M., Krolak-Salmon, P., Federico, D., Sellier, C., Auguste, N., … Rouch, I. (2017). Predictors of discharge destinations and three-month evolution of patients initially hospitalized in a cognitive behavioral unit. Journal of Alzheimer’s Disease, 60(4), 1259–1266. doi:10.3233/JAD-170419
   PubMed Web of Science ®Google Scholar
• Popay, J., Roberts, H., Sowden, A., Petticrew, M., Arai, L., Rodgers, M., … Duffy, S. (2006). Guidance on the conduct of narrative synthesis in systematic reviews. A Product from the ESRC Methods Programme Version, 1, b92.
   Google Scholar
• Rockwood, K., Stolee, P., & Brahim, A. (1991). Outcomes of admission to a psychogeriatric service. The Canadian Journal of Psychiatry, 36(4), 275–279. doi:10.1177/070674379103600407
   PubMed Web of Science ®Google Scholar
• Rouch, I., Pongan, E., Trombert, B., Fabre, F., Auguste, N., Sellier, C., … Mouchoux, C. (2017). One-year evolution of behavioral and psychological symptoms of dementia in patients initially hospitalized in cognitive behavioral units: The EVITAL prospective cohort. Journal of Alzheimer’s Disease, 57(1), 147–155. doi:10.3233/JAD-161023
   PubMed Web of Science ®Google Scholar
• Royal College of Psychiatrists. (2019). National audit of dementia care in general hospitals 2018–19: Round four audit report.
   Google Scholar
• Saidlitz, P., Sourdet, S., Voisin, T., & Vellas, B. (2017). Management of behavioural symptoms of dementia in a specialized unit care. Psychogeriatrics, 17(2), 81–88. doi:10.1111/psyg.12193
   PubMed Web of Science ®Google Scholar
• Sajatovic, M., Friedman, S. H., Sabharwal, J., & Bingham, C. R. (2004). Clinical characteristics and length of hospital stay among older adults with bipolar disorder, schizophrenia or schizoaffective disorder, depression, and dementia. Journal of Geriatric Psychiatry and Neurology, 17(1), 3–8. doi:10.1177/0891988703258821
   PubMed Web of Science ®Google Scholar
• Sampson, E. L., White, N., Leurent, B., Scott, S., Lord, K., Round, J., & Jones, L. (2014). Behavioural and psychiatric symptoms in people with dementia admitted to the acute hospital: Prospective cohort study. The British Journal of Psychiatry, 205(3), 189–196. doi:10.1192/bjp.bp.113.130948
   PubMed Web of Science ®Google Scholar
• Schneider, L. S., Tariot, P. N., Dagerman, K. S., Davis, S. M., Hsiao, J. K., Ismail, M. S., … Stroup, T. S. (2006). Effectiveness of atypical antipsychotic drugs in patients with Alzheimer’s disease. New England Journal of Medicine, 355(15), 1525–1538. doi:10.1056/NEJMoa061240
   PubMed Web of Science ®Google Scholar
• Smith, B., Hassett, A., Harrigan, S., & Fortune, T. (2010). A profile of inpatient admissions to an aged psychiatry service in Victoria. Australasian Psychiatry, 18(2), 146–151. doi:10.3109/10398560903314112
   PubMed Web of Science ®Google Scholar
• Staal, J. A., Amanda, S., Matheis, R., Collier, L., Calia, T., Hanif, H., & Kofman, E. S. (2007). The effects of snoezelen (multi-sensory behavior therapy) and psychiatric care on agitation, apathy, and activities of daily living in dementia patients on a short term geriatric psychiatric inpatient unit. The International Journal of Psychiatry in Medicine, 37(4), 357–370. doi:10.2190/PM.37.4.a
   PubMed Web of Science ®Google Scholar
• Tampi, R. R., Tampi, D. J., Balachandran, S., & Srinivasan, S. (2016). Antipsychotic use in dementia: A systematic review of benefits and risks from meta-analyses. Therapeutic Advances in Chronic Disease, 7(5), 229–245. doi:10.1177/2040622316658463
   PubMed Web of Science ®Google Scholar
• Wilkins, J. M., Goldstein, E. K., & Forester, B. P. (2019). Characteristics of hospice referrals from an inpatient geriatric psychiatry unit. The American Journal of Geriatric Psychiatry, 27(2), 162–166. doi:10.1016/j.jagp.2018.11.011
   PubMed Web of Science ®Google Scholar
• Wolverson, E., Birtles, H., Moniz-Cook, E., James, I., Brooker, D., & Duffy, F. (2019). Naming and framing the behavioural and psychological symptoms of dementia (BPSD) paradigm: Professional stakeholder perspectives. OBM Geriatrics, 3(4), 1–19. doi:10.21926/obm.geriatr.1904080
   Google Scholar
• Wolverson, E., Dunn, R., Moniz‐Cook, E., Gove, D., & Diaz‐Ponce, A. (2021). The language of behaviour changes in dementia: A mixed methods survey exploring the perspectives of people with dementia. Journal of Advanced Nursing, 77(4), 1992–2001. doi:10.1111/jan.14787
   PubMed Web of Science ®Google Scholar
• World Health Organisation. (2021). Dementia https://www.who.int/news-room/fact-sheets/detail/dementia#:~:text=Worldwide%2C%20around%2055%20million%20people,and%20139%20million%20in%202050.
   Google Scholar