The general purpose of SNACK is to increase our understanding of the aging process and to identify preventive strategies that can lead to improved health and care of the elderly. Within this framework, specific aims and research questions can be aggregated into 3 major objectives:
Functioning in healthy aging
Healthy aging is operationally defined both objectively as absence of diseases, and subjectively as feeling of good health. Social integration and social engagement will be taken into account, according to the definition of successful aging proposed by Rowe and Kahn, 1997. Well-being, life satisfaction and disability-free life expectancy are the other main indicators. Cognitive as well as physical functioning are both investigated cross-sectionally and longitudinally. Research questions are:
1. What is the “antecedent profile” of successful aging? How much do subjective factors, such as well-being and life satisfaction, contribute to a healthier and longer life?
2. Which instruments are best for describing physical and mental functioning in the very old? Is it possible to determine a functional, social, and cognitive disability? How much are these different aspects of functioning interrelated?
3. What characterises the pattern of cognitive changes in normal aging? Which specific functions are affected first (e.g., memory, speed, verbal skill, visuospatial ability)? What are the main predictors of rate of cognitive change in normal aging within demographic, social, biological, and genetic domains?
4. Do older adults have the ability to compensate for cognitive losses by means of various supportive conditions and strategies?
Determinants of the transition from healthy aging to illness/disability
Specific neurodegenerative diseases, multimorbidity, disability, and mortality are the main outcomes. The determinants are all the factors putatively related to the above-mentioned outcomes. Both current and past exposure to these potential determinants are considered as well as the cumulative effect due to the chain of events that old individuals have experienced during life. The determinants include environmental factors (occupation, residential area and migration, air pollution and life habits), social factors (education, socio-economic status, social network, life styles, and leisure-time activities), and biological factors (age, sex, genetic susceptibility, family history, medical and psychological parameters, and previous morbidity). Research questions are:
1. What is the impact of recognised mid-life risk factors (environmental, social, and biological) on ill health, disease burden, physical disability and cognitive impairment in late life?
2. Which risk factors are most strongly related to specific diseases that are common in old age? Does the relative importance of various risk factors vary as a function of the age and time of exposure?
3. Are there interactions among risk factors? How does exposure to multiple risk factors during life affect health and functioning in old age?
4. What are the principal risk factors for co-occurrence of diseases? Are those factors linked to differential survival after the age of 60?
5. Are there some protective factors in this regard? Are protective factors acting during the whole life and may they play a role even during late adulthood? When is the optimal time window for preventive actions?
Markers of early phases and progression of disease/disability
The natural history of diseases or disability is investigated from the pre-clinical and early clinical phases, through the established stage, to disease/disability resolution (recovery or death). Research questions include:
1. Is “mild cognitive impairment” a valid predictor of dementia development several years before clinical diagnosis? If so, how far back can a preclinical period be traced?
2. Is a mild cognitive impairment characterised by disturbances in different cognitive domains depending on dementia type (e.g., Alzheimer’s disease vs. vascular dementia)?
3. What is the evolution of stroke? Is depression after stroke related to previous morbidity or personality, in addition to type and localisation of stroke? Does depression after stroke increase the risk of dementia following stroke?
4. Could cognitive problems also be detected in preclinical depression? If so, is it possible to adopt a continuity view concerning the ways in which depression affects cognitive functioning? That is, is there a systematic increase in level of cognitive impairment from normal aging through subclinical depression to clinical depression?
5. How much do degenerative and vascular mechanisms coexist in determining the development of dementia? Is the pure degenerative form of dementia known as Alzheimer’s disease more common in younger ages (before 75), whereas the so-called mixed cases are more common in the very old?
6. Is the vascular cognitive impairment different from the degenerative cognitive impairment in terms of onset, distribution, and size of the impairment?
7. Which is the impact of multimorbidity on institutionalisation and mortality?