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The specific research objectives for each wave of data collection were developed by the chief investigators and form the basis of ongoing research at CRAHW, ANU. Hence every variable and outcome measure in the study has been chosen by a researcher for a specific purpose. The following section details the study measures used in this thesis.

3.4.3.1 Health variables

Self-rated health was assessed using the 12-item Short Form Health Survey (SF-12) which gives two summary measures- physical health and mental health. The SF-12 has recently been validated for use in Australia, with the SF-12 items predicting at least 90% of the variance in both the physical and mental health measures (Sanderson & Andrews, 2002).

The Brief Patient Health Questionnaire (BPHQ) was used to measure symptoms of depression (Spitzer, Kroenke, Williams, & and the Patient Health Questionnaire Primary Care Study, 1999). A study by Kiely and Butterworth (2015) found that a cut-off point of 8 on the BPHQ-9 had a sensitivity of 0.79 and specificity of 0.86. The Goldberg’s scale was also used to measure participants’

symptoms of anxiety and depression (Goldberg, Bridges, Duncan-Jones, & Grayson, 1988). This scale is an 18-item questionnaire with “Yes/No” responses to questions asking how the participant has been feeling in the past month. Items are scored 0 (no) or 1 (yes) and summed. A cut-point of 5 on the depression scale has a sensitivity of 0.81 and a specificity of 0.83. A cut-point of 7 on the anxiety scale has a sensitivity of 0.84 and specificity of 0.86 (Kiely & Butterworth, 2015).

Participants self-reported if they had been diagnosed with any of the following conditions: arthritis, high blood pressure, cancer, stroke, thyroid, diabetes, asthma bronchitis or emphysema, cataracts or heart problems.

3.4.3.2 Psychosocial variables

Participants’ level of education was measured by asking participants their highest level of schooling completed and then the level of post-secondary or tertiary education completed. The level of school completed was then used to calculate the total years of education completed.

Each participant’s social network was measured using the 6-item Lubben social network scale (Lubben, 1988). This scale has an internal reliability of 0.83. In accordance with previous research (Lubben et al., 2006) a cut-point of 12 was used to categorise participants into ‘at risk of social isolation’ or ‘not at risk’. The social support scale developed by Schuster, Kessler, and Aseltine (1990) was also used. This scale measures both positive and negative interactions with spouse, family and friends.

To measure financial status participants self-reported if they had experienced any financial problems, if they received a full or part time pension and if the pension was their only income. Levels of role strain, or assumed household responsibility, was measured using three questions. Participants were asked to indicate the extent that they were responsible for financial management, housework and providing money for the household, from “Fully responsible” to “Not at all

responsible”. The responses were summed to give a total role strain score.

Finally, mastery, or individual’s sense of control, was measured using the Pearlin Personal Mastery Scale (1981). This scale consists of 7 statements, positively and negatively worded, which participants respond to on a four-point scale from 1= “Strongly Agree” to 4= “Strongly Disagree”. Negatively worded statements were reverse coded and the scores summed. A low score suggests a high level of control and a high score suggests a low level of control. This scale has demonstrated good construct validity and internal reliability (Pearlin, Menaghan, Lieberman, & Mullan, 1981).

3.4.3.3 Behavioural variables

Smoking status was assessed by asking participants if they currently or had previously smoked. Harmful or hazardous alcohol consumption was measured using the Alcohol Use Disorders

Identification Test (Saunders, Aasland, Babor, De La Fuente, & Grant, 1993). Harmful alcohol

consumption was defined as >42 units per week for men, >28 units per week for women. Hazardous alcohol consumption was defined as 28-42 units per week for men and 14-28 units for women. Participants who had not drunk alcohol in the last year were classified as ‘abstainers.’

Participants were asked about the frequency of physical activity (from “Never” to “3 times a week or more”) and the total number of hours spent exercising per week. Each of these required separate responses for level of activity- mild, moderate and vigorous. The number of hours of exercise per week was then summed and dummy coded. None/mild exercise was coded as less than moderate or vigorous, moderate was equal to or more than 1.5 hours per week of moderate but less than 1.5 hours of vigorous, or 30 minutes to 1.49 hours per week of both moderate and vigorous per week, and vigorous activity was equal to or more than 1.5 hours of vigorous activity per week.

3.4.3.4 Cognitive variables

Short-term memory was assessed by immediate and delayed recall of the first trial of the Californian Verbal Learning Test (CVLT) (Delis et al., 1987). This test involves participants recalling a list of 16 nouns. Digit span backwards is a subtest from the Wechsler Memory Scale (Wechsler, 1981) and tests working memory. Numbers were read out to participants at one second intervals. When the participant incorrectly repeated numbers on two trials no further trials were given. The Symbol Digit Modalities Test (SDMT) (Smith, 1982) requires individuals to identify the corresponding symbol to the digits 1-9 based on a key. Participants were given 90 seconds to complete as many symbol-digit pairs as possible. The SDMT assesses participant’s processing speed. Verbal ability was measure with the Spot-the-Word test which was self-completed by the participant on a computer screen. In this task participants choose the real words from 60 pairs of words and non-words (Baddeley, Emslie, & Nimmo Smith, 1992). Finally, the Mini Mental State Examination (MMSE) (Folstein et al., 1983) was administered to participants. The MMSE was developed to screen for dementia and cognitive impairment. The MMSE is an 11-item questionnaire that tests five areas of

cognitive function: orientation to time and place, short-term memory, calculation, immediate recall, constructive ability and language. The maximum score is 30 and a score of 23 or lower is indicative of severe cognitive impairment. This cut-point has a sensitivity of 0.66, specificity of 0.99 and overall correct classification rate of 88.9% (O'Bryant et al., 2008). For the Health and memory sub-study, individuals who scored 25 or below on the MMSE were screen positive for cognitive impairment.