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AlzRisk Paper Detail
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Reference: Ravaglia, 2008
Cohort: Conselice Study of Brain Aging
Risk Factor: Physical Activity


Average Follow-up Time Detail
Person-time began between 1999 and 2000. Identification and differential diagnoses of incident cases occurred during 2003 to 2004.

Exposure Detail
"Information on physical activity was collected at baseline by trained interviewers using the Paffenbarger Physical Activity Questionnaire.20 Participants were asked 1) how many city blocks (or the equivalent: 12 block = 1 mile) they walked each day for exercise or as a part of their normal routine and about their usual outdoor walking pace; 2) how many flights of stairs they climbed each day; 3) about frequency and duration of their participation per week during the past year in any other occupational, recreational, or sport activity. According to its intensity, each activity was assigned a metabolic equivalent (mL of used O2/minute, MET, where 1 MET is proportional to the energy expended while sitting quietly) and the corresponding energy expenditure (kilocalories/week) was calculated. The measures of physical activity used for this study were as follows: energy expenditure per week in walking (from 2.5 to 4.5 METs according to pace), stair climbing (8 METs), any other moderate (3 to 6 METs) or vigorous (>6 METs) activity, and total physical activity (sum of energy expenditure in all the previously listed physical activities). Additionally, participants were classified according to whether they adhered to the recommendation for physical activity (30 minutes or more of moderate-intensity physical activity on at least 4 days per week) issued by the Centers for Disease Control and Prevention and the American College of Sports Medicine (CDCP/ACSM).21"

Ethnicity Detail
Italian men and women living in an urban municipality.

Screening and Diagnosis Detail
Screening Method:
MMSEMini-Mental State Examination (Folstein 1975)

AD Diagnosis:
NINCDS ADRDA National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association Criteria (McKhann 1984)

Total dementia definition: Dementia via DSM IV.

"A two-phase procedure was used during 1999 to 2000, consisting of a cognitive screening phase and an extensive neuropsychological assessment of those positive at screening in order to identify mild cognitive impairment (MCI) and dementia cases. The screening phase included 1) a standardized personal interview for collection of data on sociodemographic characteristics, lifestyle, medical history, ability to perform basic activities of daily living (ADL)22 and instrumental activities of daily living (IADL),23 evaluation of depressive symptoms with the Geriatric Depression Scale (GDS),24 and measurement of global cognitive function with the Italian version of the Mini-Mental State Examination (MMSE),25 for which standardized age- and education-specific coefficients are available26; 2) a standardized medical and neurologic examination; and 3) collection of fasting venous blood samples. Whenever available, previous medical records were reviewed. For subjects unable to answer because of physical or mental impairments, information was obtained from relatives and general practitioners. Subjects with MMSE score below 24 were considered positive at cognitive screening and underwent further neuropsychological assessment with the Mental Deterioration Battery (MDB).27 MDB includes tests for evaluation of memory (immediate and delayed recall of Rey’s 15 words), language (sentence construction), frontal function (phonological word fluency), abstract reasoning (Raven’s 47 progressive colored matrices), and visuospatial abilities (freehand copying of drawings and copying of drawings with landmarks). MDB is validated for use in rural and poorly educated Italian subjects. Memory was additionally tested using the prose memory test.28 All of these tests are provided with standardized thresholds for the definition of impairment in the corresponding cognitive domain (score ≤1.5 SD the mean for a reference adult Italian population-based cohort), and age- and education-specific coefficients to be applied to the subject’s raw score before comparison with the corresponding threshold.

Subjects with MMSE below 10 did not receive further neuropsychological testing. Whenever recent neuroradiologic data were not available, the subject was scheduled for a noncontrast CT brain scan. Standardized information about functional and mental status of subjects positive at cognitive screening was also obtained from a collateral informant (a relative or any other person with a reliable knowledge of the individual, including the subject’s medical practitioner). Dementia was diagnosed with Diagnostic and Statistical Manual of Mental Disorders–IV clinical criteria,29 AD with National Institute of Neurological and Communicative Disorders and Stroke–Alzheimer’s Disease and Related Disorders Association criteria,30 VaD with National Institute of Neurological Disorders and Stroke–Association Internationale pour la Recherche en l’Enseignement en Neurosciences criteria.31 Diagnoses were independently made by two physicians who were blinded to the Paffenberger questionnaire’s results."

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

Further analysis were conducted for Kcal/wk due to walking, climbing, moderate activity, and vigorous activity. The results for total Kcal/wk are reported here.

AD Covariates:
Aage
Eeducation
Ggender
APOE4APOE e4 genotype
Ccancer
CVDcardiovascular disease
CPDchronic pulmonary disease
CHDcoronary heart disease
DMdiabetes mellitus
HTNhypertension
HCYplasma homocysteine

TD Covariates:
Aage
Eeducation
Ggender
APOE4APOE e4 genotype
Ccancer
CVDcardiovascular disease
CPDchronic pulmonary disease
CHDcoronary heart disease
DMdiabetes mellitus
HTNhypertension
HCYplasma homocysteine

"Covariates were defined using data collected at baseline. Educational status was categorized as 3 vs 4 or more years of formal education, because at the time the CSBA participants went to school the first educational degree was achieved after 3 years of schooling.

Comorbidity was defined as the concurrent presence of two or more of the following medical conditions: hypertension, cardiovascular disease (history of myocardial infarct and congestive heart failure), cerebrovascular disease (history of stroke or TIA), diabetes, chronic pulmonary disease, and cancer. Hypertension was defined as blood systolic pressure ≥130 mm Hg, blood diastolic pressure ≥85 mm Hg (using the average of two seated measurements), or currently using an antihypertensive medication. All other diagnoses were based on medical history as provided by the participants and their medical practitioners, including revision of available medical records. ADL motor disability was defined as need for help in performing one or more of the corresponding daily living activities because of motor impairment."