Physical Activity Predicts Population-Level Age-Related Differences in Frontal White Matter

Physical activity has positive effects on brain health and cognitive function throughout the life span. Thus far, few studies have examined the effects of physical activity on white matter microstructure and psychomotor speed within the same, population-based sample (critical if conclusions are to extend to the wider population). Here, using diffusion tensor imaging and a simple reaction time task within a relatively large population-derived sample (N = 399; 18–87 years) from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN), we demonstrate that physical activity mediates the effect of age on white matter integrity, measured with fractional anisotropy. Higher self-reported daily physical activity was associated with greater preservation of white matter in several frontal tracts, including the genu of corpus callosum, uncinate fasciculus, external capsule, and anterior limb of the internal capsule. We also show that the age-related slowing is mediated by white matter integrity in the genu. Our findings contribute to a growing body of work, suggesting that a physically active lifestyle may protect against age-related structural disconnection and slowing.


THE QUESTIONNAIRE IS DIVIDED INTO 3 SECTIONS
• Section A asks about your physical activity patterns in and around the house.
• Section B is about travel to work and your activity at work. It may be skipped by people who have not worked at any stage during the last 12 months.
• Section C asks about recreations that you may have engaged in during the last 12 months.

H O M E A C T I V I T I E S GETTING UP AND GOING TO BED Please put a time in each box
A v e r a g e o v e r t h e p a s t y e a r

Section B A C T I V I T Y A T W O R K
Please answer this section only if you have been in paid employment at any time during the last 12 months or you have done regular, organised voluntary work.
If not please go to page 9

TYPES OF WORK DURING THE LAST TWELVE MONTHS
• We would like to know what full or part-time jobs you have done in the last 12 months.
• You may have held a single job or have held two jobs at once.
• If you have changed jobs with the same employer, you should enter it as a change of job only if it entailed a substantial change in physical effort.

EXAMPLE
Someone who worked full-time for 6 months, then retired, rested for 3 months and then started a voluntary job for 6 hours a week, would complete the questions as follows.

Job 1
Job 2 Name of occupation nurse shop work How many hours per week did you usually work?

6
For how many months in the last 12 months did you do this work?

3 ACTIVITY LEVELS AT YOUR WORK
Now we would like you to take the total number of hours you worked per week in each job and divide them up according to your activity level. For how many months in the last 12 months did you do this work?

ACTIVITY LEVELS AT YOUR WORK
Now we would like you to take the total number of hours you worked per week in each job and divide them up according to your activity level.

R E C R E A T I O N
The following questions ask about how you spent your leisure time.
Please indicate how often you did each activity on average over the last 12 months.
For activities that are seasonal, e.g. cricket or mowing the lawn, please put the average frequency during the season when you did the activity.
Please indicate the average length of time that you spent doing the activity on each occasion.

EXAMPLE
If you had mowed the lawn every fortnight in the grass cutting season and took 1 hour and 10 minutes on each occasion.
If you went walking for pleasure for 40 minutes once a week.
You would complete the table below as follows: Please give an answer for the AVERAGE TIME you spent on each activity and the NUMBER OF TIMES you did that activity in the past year.  Please give an answer for the NUMBER OF TIMES you did the following activities in the last 12 months and the AVERAGE TIME you spent on each activity. This Cam-CAN paper questionnaire is intended to capture aspects of your life that are difficult to measure during the face-to face interview. It consists of two areas: i) a lifetime experiences questionnaire ii) a questionnaire on physical activity.
Please complete the questionnaire before your home interview; if you have any questions feel free to ring for advice.
To complete the questionnaire, please continue and answer each question as accurately as possible. Completing the questionnaire will take about 20-40 minutes. The Cam-CAN research interviewer will collect the questionnaire during the home interview.

EMPLOYMENT
You will be asked about the main jobs that you have undertaken for different periods of your life. The enclosed guide gives examples of job titles and how we will code them. Please enter this sort of title. We also ask for the number of people you employed, or supervised during that period. Please enter the job titles below, please try and be as explicit as possible. If you were in charge of people please indicate the approximate number. If you are not sure of the code enter your job title in the box provided. Page 12

Section B ACTIVITY AT WORK
Please answer this section only if you have been in paid employment at any time during the last 12 months or you have done regular, organised voluntary work.

TYPES OF WORK DURING THE LAST TWELVE MONTHS
We would like to know what full or part-time jobs you have done in the last 12 months. You may have held a single job or have held two jobs at once. If you have changed jobs with the same employer, you should enter it as a change of job only if it entailed a substantial change in physical effort.

EXAMPLE
Someone who worked full-time for 6 months, then retired, rested for 3 months and then started a voluntary job for 6 hours a week, would complete the questions as follows Page 16

Section C RECREATION
The following questions ask about how you spent your leisure time. Please indicate how often you did each activity on average over the last 12 months. For activities that are seasonal, e.g. cricket or mowing the lawn, please put the average frequency during the season when you did the activity. Please indicate the average length of time that you spent doing the activity on each occasion.

EXAMPLE
If you had mowed the lawn every fortnight in the grass cutting season and took 1 hour and 10 minutes on each occasion, and you went walking for pleasure for 40 minutes once a week, you would complete the table below as follows: Please give an answer for the AVERAGE TIME you spent on each activity and the NUMBER OF TIMES you did that activity in the past year.
Number of times you did the activity in the last 12 months Average time per episode Please give an answer for the NUMBER OF TIMES you did the following activities in the last 12 months and the AVERAGE TIME you spent on each activity.

LIFETIME EXPERIENCE QUESTIONNAIRE
This questionnaire covers your current activities, your training courses and your employment history. Please complete all sections relevant to you. You may be asked to skip sections.

YOUNG ADULTHOOD TRAINING
The following questions apply to the time in your life between 13 and 29 years of age.
Please detail all types of training or study undertaken from age 13 to 29. Please enter the job titles below, please try and be as explicit as possible. If you were in charge of people please indicate the approximate number. If you are not sure of the code enter your job title in the box provided.

TYPES OF WORK DURING THE LAST TWELVE MONTHS
We would like to know what full or part-time jobs you have done in the last 12 months. You may have held a single job or have held two jobs at once. If you have changed jobs with the same employer, you should enter it as a change of job only if it entailed a substantial change in physical effort.

EXAMPLE
Someone who worked full-time for 6 months, then retired, rested for 3 months and then started a voluntary job for 6 hours a week, would complete the questions as follows What jobs have you held in the last 12 months, and how many months in the year did you do them?

Job 1 Job 2
Name of occupation How many hours per week did you usually work?
For how many months in the last 12 months did you do this work?

ACTIVITY LEVELS AT YOUR WORK
Now we would like you to take the total number of hours you worked per week in each job and divide them up according to your activity level. In an average working day in job 1 did you (please tick all that apply) o Kneel for more than an hour in total? o Squat for more than an hour in total? o Get up from kneeling or squatting more than 30 times?
In an average working day in job 2 did you o Kneel for more than an hour in total? o Squat for more than an hour in total? o Get up from kneeling or squatting more than 30 times? Page 18

Section C RECREATION
The following questions ask about how you spent your leisure time. Please indicate how often you did each activity on average over the last 12 months. For activities that are seasonal, e.g. cricket or mowing the lawn, please put the average frequency during the season when you did the activity. Please indicate the average length of time that you spent doing the activity on each occasion.

EXAMPLE
If you had mowed the lawn every fortnight in the grass cutting season and took 1 hour and 10 minutes on each occasion, and you went walking for pleasure for 40 minutes once a week, you would complete the table below as follows: Please give an answer for the AVERAGE TIME you spent on each activity and the NUMBER OF TIMES you did that activity in the past year.
Number of times you did the activity in the last 12 months Average time per episode Please give an answer for the NUMBER OF TIMES you did the following activities in the last 12 months and the AVERAGE TIME you spent on each activity. To complete the questionnaire, please continue and answer each question as accurately as possible. Completing the questionnaire will take about 40-60 minutes. The Cam-CAN research interviewer will collect the questionnaire during the home interview.
Thank you for your participation.

LIFETIME EXPERIENCE QUESTIONNAIRE
This questionnaire covers your current activities, your training courses and your employment history. Please complete all sections relevant to you. You may be asked to skip sections.

YOUNG ADULTHOOD TRAINING
The following questions apply to the time in your life between 13 and 29 years of age.
Please detail all types of training or study undertaken from age 13 to 29.

EMPLOYMENT
You will be asked about the main jobs that you have undertaken for different periods of your life. The enclosed guide gives examples of job titles and how we will code them. Please enter this sort of title. We also ask for the number of people you employed, or supervised during that period. Please enter the job titles below, please try and be as explicit as possible. If you were in charge of people please indicate the approximate number. If you are not sure of the code enter your job title in the box provided.