Longitudinal data

Longitudinal studies on ageing are ideal for providing evidence for addressing current and future concerns associated with population ageing. Both NI and ROI now have longitudinal studies on ageing, and will be important sources of information on population ageing that is comparable across the island of Ireland and will provide important data for informing policy and practice on dementia. While there are dementia-focused longitudinal cohort studies in other countries across Europe (JPND, 2013), there are currently no such studies on the island of Ireland.

Northern Ireland Mortality Study

Queens University Belfast
The Northern Ireland Mortality Study (NIMS) is a large-scale data linkage study that links the 1991, 2001 and 2011 Census returns for the whole of the enumerated population (approximately 1.6 million individuals) to subsequently registered mortality data from the General Register Office (GRO).
While larger than NILS it is more limited in scope, focusing only on the linkage of mortality data. Data from this study features in one of the papers in the journal section of this review.

Northern Ireland Longitudinal Study

Queens University Belfast
The Northern Ireland Longitudinal Study (NILS) is a large-scale, representative data-linkage study created by linking data from the Northern Ireland Health Card Registration system to the 1981, 1991, 2001 and 2011 Census returns and to administrative data from other sources such as births, deaths an
d marriages. The result is a 30 year plus longitudinal data set which is regularly being updated. The sample is - c. 28% of the Northern Ireland population (approximately 500,000 individuals and accounting for approximately 50% of households). It is designed for statistics and research purposes only and is managed by Northern Ireland Statistics and Research Agency under Census legislation. The NILS offers the potential to look at a wide range of important social and epidemiological issues including occupational mortality; fertility change; family structure; women’s occupations; geographical and social inequalities in health; social mobility; and the health of ethnic minorities and religious groups. All research carried out on the NILS database must be related to health and social care.

Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA)

Queen’s University Belfast

NICOLA (Northern Ireland Cohort for the Longitudinal Study of Ageing) (http://nicola.qub.ac.uk/) is NI’s longitudinal study of ageing.

The aim of NICOLA is to obtain information in relation to the experiences of ageing together with a range of other dimensions of lifestyle, health and socioeconomic circumstances. Recruitment for NICOLA began in early autumn 2013, when some 8,500 men and women aged 50 years and above were randomly selected from all over 50’s living in the community and invited to join the study.

Study participants are interviewed every two years, complete a health assessment every four years, and are followed-up for a period of at least 10 years. Information is captured on health and social care utilisation, health behaviours, medication, mental, physical and cognitive health, employment, finances, retirement, social connectedness, social participation, driving and travel, housing, consumption and expectations. Participants’ cardiovascular, cognitive and respiratory function is assessed as well as their physical activity, visual health and body composition. Biological samples provided by participants undergo detailed laboratory analysis, including genetic analysis.

Because NICOLA closely follows the approach taken by TILDA (ROI) and that of other longitudinal studies on ageing including ELSA (England), the establishment of NICOLA will provide an important evidence base for addressing current and emerging issues associated with population ageing across the island of Ireland. NICOLA has a special focus on intergenerational poverty, transition points in ageing and the effects of diet on the ageing process and includes questions of unique relevance to NI. NICOLA comprises an interview and a health assessment. The interview captures information on health and social care utilisation, health behaviours, medication, mental, physical and cognitive health, employment, finances, retirement, social connectedness, social participation, driving and travel, housing, consumption and expectations. The health assessment includes a review of cardiovascular, cognitive and respiratory function; physical activity, visual health and body composition. Participants are also to be asked to provide biological samples for detailed laboratory analysis, including genetic analysis.

Wave 1 interviews have now been completed with 8500 participants and a report on preliminary findings published:

Cruise, S. and Kee, F. (2017) Early key findings from a study of older people in Northern Ireland The NICOLA Study, Belfast, Queens University Belfast.

Wave 2 interviews began in 2017.

TILDA-IDS

Trinity College Dublin

IDS-TILDA is the Intellectual Disability Supplement to TILDA. It is a longitudinal study that researches ageing among people with an intellectual disability aged 40 and over in ROI.

It is the first study of its kind in Europe, and the only study that can directly compare the ageing of people with intellectual disability with that of the general ageing population. It includes a cognitive assessment using four measures: reported diagnosis of memory disorder; self-rated memory, orientation in time, and Test for Severe Impairment.

The reports of the first, second and third waves of data are available at the IDS-TILDA website and can be accessed here.  

McCarron, M., Swinburne, J., Burke, E., McGlinchey, E., Mulryan, N., Andrews, V., Foran, S. and McCallion, P. (2011) Growing Older with an Intellectual Disability in Ireland: Fist Results from the Intellectual Supplement of The Irish Longitudinal Study on Ageing, School of Nursing and Midwifery, Trinity College Dublin, Dublin.  

Burke, E., McCallion, P. and McCarron, M. (2014) Advancing Years: Different Challenges Wave 2 IDS-Tilda: Findings on the Ageing of People with an Intellectual Disability,  School of Nursing and Midwifery, Trinity College Dublin, Dublin.  

Mary McCarron, Margaret Haigh and Philip McCallion (Eds). (2017) Health, Wellbeing and Social Inclusion: Ageing with an Intellectual Disability in Ireland Evidence from the First Ten Years of The Intellectual Disability Supplement to The Irish Longitudinal Study on Ageing (IDS-TILDA), School of Nursing and Midwifery, Trinity College Dublin, Dublin.  

A series of related reports and publications can be found on the IDS-TILDA website https://www.tcd.ie/tcaid/assets/pdf/wave3report.pdf

The Irish Longitudinal Study on Ageing (TILDA)

Trinity College Dublin

The Irish Longitudinal Study on Ageing (TILDA) is a longitudinal study of a nationally representative sample of older 8,000 older people aged 50 years and over living in the community in Ireland.

The overarching aim of TILDA is to improve the understanding of how health, economic and social circumstances contribute to (successful) ageing and to make Ireland the best place in the world to grow old.

TILDA collects information on health, economic and social circumstances from people aged 50 and over in a series of data collection waves once every two years. Over 8,500 people took part in the first wave of TILDA in 2009 and 2010. Participants were asked questions about a range of topics including health, housing, social support, work, retirement, pensions and quality of life and this was followed up with a health assessment. The results are published in a report called ‘Fifty Plus in Ireland 2011: First Results from The Irish Longitudinal Study on Ageing’ (Barrett et al., 2011).

Wave 2 of the study, which commenced in early 2012, is now complete. Wave 2 involved re-visiting and re-interviewing participants from the first wave. In addition to the topics covered in Wave 1, some new questions were added, including on personality. There was no separate health assessment during this wave, but the interviewers took a measure of handgrip strength and walking speed when they visited participants in their homes. The first results from Wave 2 have now been published in a report titled 'The Over 50s in a Changing Ireland: Economic Circumstances, Health and Well-Being' (Nolan et al., 2014).

Wave 3 of the study was completed in 2015.  Participants were interviewed in their own home with 80% also completing a health assessment.  Both the interview and health assessment included cognitive testing. The health assessment also included measures of sensory function, and cardiovascular health.  Questions on cardiovascular disease and behavioural health (smoking, physical activity and sleep) cholesterol screening, employment, and social connectedness have much relevance for the potentially modifiable risks factors associated with dementia. There is evidence that occupational level, educational level, and social engagement can enhance brain function and protect against or at least delay the onset of dementia.

The first results from Wave 3 were published in a report entitled ‘Health and Wellbeing: Active Ageing for Older Adults in Ireland. Evidence from the Irish Longitudinal Study on Ageing’.

Wave 4 took place during 2016 with over 6000 interviews carried out in participants own homes. New questions in this wave were related to health literacy and childhood health.  No health assessment was carried out in this wave but a measure of handgrip strength and walking speed were taken.

Wave 5 is scheduled to take place in 2018.  This will again involve a personal interview in the participant's home and a self-completion questionnaire. There will be no health assessment but measures of hand grip strength and walking speed will be taken.

A comprehensive list of TILDA reports, academic papers and study documents can be found on the TILDA website, several of which address cognitive function/impairment and which have relevance of policy and practice on dementia, but none address dementia specifically.