Twins have been assessed with brain MRI, cognitive, health and epigenetic measures. A total of 227 individuals have participated in assessments at either 1,2,3 or 4 time points.The total number of assessments are at the moment above 600 with time point 4 participants still being recruited. 22 training intervention groups including a total 118 participants took part in the training intervention. The training sessions have amounted to over 590 hours of in-lab virtual reality cogntive training and 970 hours of laptop based training at home.
One of the project’s most innovative methods is PlastiCity, an immersive virtual reality (VR)-based navigation training program. This intervention combines spatial navigation tasks with physical movement on a stationary bike, directly targeting hippocampal-dependent memory functions, which are known to decline with age. VR technology enables the introduction of novel tasks and stimuli while collecting fine-grained behavioral data, including movement patterns, position tracking, and head and eye movements in real-time. This setup also trains complex cognitive processes, such as prospective memory—the ability to remember to carry out future actions, a skill difficult to train using traditional lab-based methods.
Participants were instructed to complete specific tasks while navigating virtual routes, enhancing prospective memory, executive functioning, and monitoring abilities. The intervention allowed us to gather detailed behavioral data, from precise measures like reaction times and movement patterns to broader performance metrics such as the number of targets reached or deviations from the shortest path. A key strength of the VR setup is its reliance on true locomotion via stationary bikes, making the experience more ecologically valid.
Expanding on PlastiCity, we developed MiniCity, a laptop-based spatial memory and planning task designed for broader accessibility. This virtual navigation game challenges participants to identify landmarks within a city divided into distinct thematic zones, allowing researchers to assess spatial cognition without requiring VR equipment.
Finally, Ursa Mirror refines motor learning analysis using the Mirror Tracing Task (MTT), providing high-resolution measures of motor control and learning, particularly relevant for aging and neurodegenerative research.
A key finding, as demonstrated by Walhovd et al. (2024), is the link between lower BW and reduced cortical volume. A reduction of 600g (approximately one standard deviation) was associated with a 1.1–1.6% decrease in cortical volume. Even among genetically identical MZ twins, differences in BW predicted variations in brain structure and function, emphasizing the significant role of non-genetic early-life factors. It was also shown that differences in birth weight appeared to have a stable effect across the lifespan.
In a recent presentation, as a part of a peer-reviewed conference proceeding, Walhovd et al. (2024) showed preliminary results indicating that training with PlastiCity led to measurable increases in hippocampal volume. Furthermore, differences in birth weight among MZ twins showed that the higher BW twin tended to train more and achieve higher levels of cognitive performance.
Moreover, we find that changes in functional connectivity with training, and with a higher training time, the lower birth weight twin becomes in terms of brain structural parameters more similar to the higher birth weight twin with training. These preliminary results have been presented at the AAIC- Alzheimer's Association International Conference (2024)and the HBM-Human Brain Mapping conferences summer 2023, and the findings attracted much interest.
