PATH Progress November 2008
Data Collection
Publications (updated 22nd July 2009)
Data Collection
Each wave of data collection takes place over three years, with the young, midlife and older cohorts interviewed over consecutive years. Interviewers travel around Australia to conduct follow-up interviews with those who have moved away from the ACT/Queanbeyan area, while those currently living overseas are asked to complete an interview by mail or email.
In 2006, Associate Professor Kaarin Anstey led a successful NHMRC Project grant application with Helen Christensen, Andrew Mackinnon, Peter Butterworth and Simon Easteal, which provided funding for a third wave of data collection. Wave 3 interviews commenced in May of 2007. We have completed interviewing the youngest (20+) cohort and are currently interviewing the midlife (40+) cohort.
The diagram below shows the number of participants in each cohort with dates of assessment
Analysis of PATH data
In addition to CMHR staff, a number of researchers from other organisations have been allowed access to the PATH data for research purposes. Data Sharing Agreement is required for sharing of PATH data and only de-identified data is released. Professor Simon Easteal from the John Curtin School of Medical Research is responsible for the genetic analysis using the DNA extracted from the cheek swabs provided at Wave 1. The National Centre for Epidemiology and Population Health (NCEPH) have a group of researchers concentrating on data related to job stress and health. A group of researchers led by Professor Perminder Sachdev at the Neuropsychiatric Institute, University of NSW are focusing on analysis of MRI and blood data and researchers at National ICT Australia work on a collaborative project analyzing MRI scans. In addition to many national collaborators, we also have several international collaborators from institutions such as Oregon State University in the U.S.A., Brunel University in the U.K., and the Max Planck Institute for Human Development in Germany. Five PhD students have completed their degree analyzing PATH data and we currently have four PhD students analysing aspects of the PATH data for their PhD dissertations.
Selected Recently Published Findings from PATH
Volunteering and mental health
Data from the second wave of the PATH project was used to investigate relationships between 64 to 68 year-olds' time spent volunteering and levels of psychological well-being. Participants who reported taking part in moderate levels of volunteer work also reported higher levels of well-being than both those who did not volunteer, and those who engaged in more than around 15 hours of voluntary work per week. The results suggest that taking part in volunteer activity in later life not only has broader social benefits, but is also associated with benefits to the individual who volunteers. However, there appears to be an optimal level of volunteering for maintaining wellbeing.
Windsor, T. D., Anstey, K. J., & Rodgers, B. (2008). Volunteering and psychological wellbeing among young-old adults: How much is too much? The Gerontologist, ;48, 59-70.
The effect of the Canberra bushfires on neurocognitive functioning
Since trauma experiences are generally random and unpredictable, it is very difficult for researchers to have access to such pre-trauma measures. In the PATH Through Life project, 2404 participants in aged 20 to 24 years were interviewed for this longitudinal study and 2139 (89.0%) were then re-interviewed after the Canberra bushfires that occurred in January 2003. Neurocognitive measures were obtained from these trauma-exposed participants both before and after the trauma. Researchers found that PATH participants who screened positive for post traumatic stress disorder (PTSD) had significantly poorer neurocognitive skills prior to the trauma experience, but that, in the main, their measures of these skills did not decline significantly as a result of their being exposed to this trauma or experiencing PTSD symptoms. It was concluded from this study that having poorer neurocognitive skills following exposure to trauma may not be the result of the trauma experience and related PTSD symptoms. Instead having poorer neurocognitive abilities is likely to be a risk factor for developing PTSD.
Parslow RA, Jorm AF. (2007) Pre-trauma and post-trauma neurocognitive functioning and PTSD symptoms in a community sample of 1599 young adults. Am J Psychiatry 164:509-515.
Effects of the gene APOE on brain atrophy in a relatively young age group
Apolipoprotein or APOE is the main genetic risk factor for non-familial Alzheimer’s disease. Carriers of one of the variants of the APOE gene, the E4 allele, have been shown to be at higher risk of brain atrophy, and to be affected by cognitive impairment earlier and more often than those who do not carry this form of APOE. Researchers investigated whether APOE E4 effects were already detectable in this relatively young and healthy 60-64year old in the PATH study. They compared measures of cerebral gray matter between the APOE E4 carriers and non-carriers as well as the volume of the hippocampus, a brain structure involved in memory function which is affected early in dementia and found no differences. These recently published results are important as they show that the negative effects associated with APOE E4 demonstrated in other samples of ageing individuals are not yet detectable in the early sixties in a relatively healthy, well-educated, and affluent sample.
Cherbuin, N., Anstey, K. J., Sachdev, P., Maller, J. J., Meslin, C., Mack, H., Wen, W., & Easteal, S. (2007). Total and regional grey matter volume is not related to APOE*E4 status in a community sample of middle-aged individuals. Journal of Gerontology: Medical Sciences. 24, 348-62
Subtle changes in brain white matter in the 40s
The brains of elderly individuals often show subtle changes in the white matter, which have become of increasing interest with the wide availability of MRI scans. It is thought that these changes are due to a gradual increase in abnormalities in small blood vessels of the brain as we age. The changes are more prominent in those who have high blood pressure or diabetes, or have other risk factors for blood vessel disease such as smoking, high cholesterol, obesity and heart disease. Previous work done in the PATH Through Life Study has shown that >90% of otherwise healthy individuals in their early 60s have some of these changes on MRI. Even through subtle, they are related to mild slowing of movement and the speed of information processing in the brain. We recently examined an even younger cohort of healthy individuals all in the mid to late 40s, for these lesions. Small white matter lesions were seen in 1 in 2 individuals in this age group. They were slightly more common in women and in current smokers or abusers of alcohol but not hypertension or the levels of blood pressure. Our work, which is quite unique internationally, suggests that interventions to prevent WMHs should begin early in life. This is one area of preventative medicine that is likely to pay dividends in protecting our brains as we grow old.
Wen, W., Chen, X., Anstey, K. J, & Sachdev, P. S. (7/03/08). White matter hyperintensities in the forties: The prevalence and topography in an epidemiological sample aged 44-48. Human Brain Mapping
Prevalence and incidence of Mild Cognitive Disorders in the 60s
Researchers from PATH aimed to estimate incidence rates of Mild Cognitive Impairment and related disorders, and conversion to dementia. After analyzing the cognitive assessments and clinical data from PATH wave 2 they found that the annual incidence of dementia was 0.25%. Prevalence of Mild Cognitive Impairment was 4.2%, Age Associated Memory Impairment was 2.4%, Age-Associated Cognitive Decline was 7.6%, Mild Neurocognitive Disorders was 12.9% and Other Cognitive Disorder was 7.3%. The prevalence of any diagnosis of any mild cognitive disorder (Any-MCD) was 29.5% and the annual incidence rate for Any-MCD was 5.7%. Agreement for specific diagnoses between Waves 1 and 2 was fair to poor (0 to 47.0%) but agreement for Any-MCD over 4 years was 89.0%. We concluded that diagnoses of mild cognitive disorders do not predict dementia at four year follow-up in young-old adults. Prevalence rates for mild cognitive disorders vary greatly depending on criteria and time of assessment.
Anstey, K. J., Cherbuin, N., Christensen, H., Burns, R., Reglade-Meslin, C., Salim, A., Kumar, R., Jorm, A. F., Sachdev, P. (2008) Follow-up of Mild Cognitive Impairment and Related Disorders Over 4 years in Adults in Their Sixties: The PATH Through Life Study. Dementia and Geriatric Cognitive Disorders. 26:226-233.
Evaluation of brain reserve in the PATH 60s
The brain reserve hypothesis proposes that the endowment of greater ‘reserve’ offsets the biological effects of ageing and disease. Very few research investigations have directly tested the brain reserve hypothesis and this has been particularly the case for younger old age groups, including individuals in their mid or late 60s. Years of education and brain size (as measures of reserve) were examined in a sample of 472 PATH participants aged 60-64 years at baseline. The association between these measures and brain atrophy, white matter hyperintensities (WMH) and cognitive decline were measured. Although there were declines on a test of cognitive speed, there was no protection conferred by the possession of a larger brain or by higher level of formal education. There were no relationships established between indices of brain health (WMH, brain atrophy) and cognitive decline. These results are not consistent with the brain reserve hypothesis, but changes in cognition were small and the contribution of reserve may be minor in early old age.
Christensen, H., Batterham, P., MacKinnon, A., Anstey K.J. & Sachdev, P. (accepted 10/10/08) Education, atrophy and cognitive change in an epidemiological sample of early old age. American Journal of Geriatric Psychiatry
The preponderance of depression and anxiety in women
Research evidence shows that women experience higher levels of depression and anxiety than men do, however, the reasons for these gender differences remain unclear. PATH researchers have examined possible explanations. Initially they hypothesised that item bias in the scales used to measure depression and anxiety might be responsible for gender differences in overall levels of symptomology, however, this hypothesis was not supported. Following on from this work, a second paper examined potential psychosocial risk factors (mediators) for the preponderance of depression and anxiety in women. This research found that women across three age groups were more exposed to negative interpersonal events and childhood adversity than men were, and that these factors were associated with their greater psychological distress. Women were also found to more often possess harmful personality characteristics and coping styles than men, such as low levels of mastery, as well as high levels of behavioural inhibition, negative rumination and neuroticism. They also were more likely to have poor physical health and low participation in physical activity.
Leach, L.S., Christensen, H., & Mackinnon, A.J (2008). Gender differences in the endorsement of symptoms for depression and anxiety: Are gender biased items responsible? Journal of Nervous and Mental Disease, 196(2), 128-135.
Association of Type 2 Diabetes with Depression, Brain atrophy and Reduced Fine
Motor Speed in a 60-64 Year Old Community Sample
The complex relationship of type 2 diabetes to depression, cognition, and structural brain abnormalities is poorly understood. We investigated this in the 60-64 year old PATH MRI sub-study participants. In this sub-sample 39 subjects had type 2 diabetes and 428 did not have this disorder. All underwent physical examinations, assessment of depression, cognitive assessments, brain magnetic resonance imaging scans and fasting blood tests. Descriptive analyses showed that those with diabetes were more likely to have poor physical health, a bigger body mass index, and higher scores of depression and anxiety compared with those without diabetes. Having diabetes was also found to be associated with greater total brain atrophy and larger CSF volumes and poorer fine motor dexterity and these were found to be independent of depression, vascular risk factors and small vessel disease of the brain.
Kumar, R. Anstey, K.J. Cherbuin, N. Wen, W., Sachdev, P. (accepted 17/08/08) Association of Type 2 Diabetes with Depression, Brain Atrophy and Reduced Fine Motor Speed in a 60-64 year old Community Sample. American Journal of Geriatric Psychiatry
Suicidal ideation and attempts
There is currently a lack of epidemiological data on suicidal behaviour in the field of suicidology, and more specifically in the Australian context. PATH is an important study for examining suicidality because it addresses the issue of suicidality across the adult life course. Analyses of PATH data have shown that men aged 60-64 were 2/3 more likely to have suicidal thoughts than their female counterparts and being underemployed also dramatically increased the likelihood of experiencing suicidal ideation within this age group. However, perception of mastery over one’s life was highly protective against suicidal ideation among younger and middle-aged adults.
We have also conducted research to find out what distinguishes those who have suicial ideation, from those who go on to attempt suicide. This distinction is critical for the targeting of prevention programs, yet there has been little research that has allowed for this distinction to be made. Again, differences were found across age and gender. Unemployment was found to be particularly important during middle age, where suicide ideators without work were nearly nine times more likely to attempt than those who worked. Further, male ideators with a physical illness were nearly four times more likely to report a suicide attempt. Another key finding was that depression and anxiety did not distinguish between those who reported ideation, and ideators who also attempted.
Fairweather, A. K., Anstey, K. J., Rodgers, B., & Butterworth, P. (2006) Factors distinguishing suicide attempters from suicide ideators in a community sample: Social issues and physical health problems. Psychological Medicine, 36, 1235-46
Fairweather, A. K., Anstey, K. J., Rodgers, B., Jorm, A. F., & Christensen, H. (2007). Age and gender differences among suicidal ideators: prevalence and correlates. Journal of Nervous and Mental Disease, 195, 130-136
Publications
As of September 2009 103 papers have been published based on analyses of PATH data. To see the list of publications click on 'PATH Publications'.
