Samenvatting

An increasing life expectancy brings higher risks for getting a neurodegenerative disorder like Alzheimer’s disease (AD). As there is still no cure for this disease, expenses in health care keep rising because most of the care for patients with AD are from nursing homes and hospitals. The change from healthy aging to AD sometimes has an in between state, known as mild cognitive impairment (MCI). In that state, patients do have problems with their memory but are not limited in their activities of daily life. Slowing down the MCI state or preventing the onset of AD could be very useful to reduce the costs for this disease.
As the hippocampus is responsible for, among others, memory, the memory problems in MCI patients are probably due to a loss of hippocampal volume. In healthy elderly, exercising seems as a way to prevent age related atrophy of the hippocampus and their related subfields (e.g. dentate gyrus). In MCI patients, the atrophy rate is even larger than in healthy elderly but not as large as in AD patients, contributing to the idea that MCI is a state between healthy aging and AD. However, little literature exists about the influence of exercising on volumes of the hippocampus in a MCI population. Therefore, it is interesting to investigate what influence exercising could have on hippocampal volume in a MCI population, given the positive results in healthy elderly.
This study was a part of the NeuroExercise study, where participants with MCI exercise for 12 months according to a structured exercise program. At the beginning of the study and halfway (6 months into the program) a MRI scan was made to be able to look at the differences in brain volumes after half a year of exercising. The volumes of the hippocampus and dentate gyrus are determined, as in the dentate gyrus neurogenesis could possibly be stimulated by exercising. 17 participants had two MRI’s (at 0 and 6 months) and their scans were analysed in the program FreeSurfer. FreeSurfer is software based on in- and ex-vivo data and shown to have accuracy and sufficient sensitivity in detecting changes in non-cortical structures.
With a multiple regression the relation between the dependent variables and the independent variables were determined. The dependent variables were the change in volume in hippocampus and dentate gyrus after 6 months in the program (Δ volume). The independent variables were the exercise groups (aerobic, anaerobic or control), the amount of exercise classes followed in 6 months and activity level measured with an Actiwatch.
The regression analysis does not show a statistical relation between the dependent and independent variables. However, only the dentate gyrus seems to benefit from the amount of exercise classes, but far from significant (p=0,191 for the left dentate gyrus and p=0,157 for the right dentate gyrus). The correlation between hippocampal volume at T0 and age is expected to be negative (i.e. higher age, lower hippocampal volume) because of the age related atrophy of the brain. This correlation was only minimal (R^2=0,271 for the left side and R^2=0,040 for the right side). When looking at the influence of the amount of exercises on the change of volume, it is seen that the volumes of the right hippocampus and dentate gyrus remain at a stable level or increase when participants exercise less than a 100 times in 6 months.
These results thus suggest that the amount of exercising, when below the threshold of a 100 times in 6 months, keep the volumes of the right hippocampus and dentate gyrus at a stable level or increase the volumes. However, these findings are not statistically significant and further research is needed to confirm this relation. https://www.linkedin.com/in/ida-van-de-water-9246a1118/