A cognitive mapping test to check for ‘pre-clinical’ signs of dementia could help earlier diagnosis, claims a study
Researchers from Washington University in St. Louis have used a virtual maze navigation experiment to examine whether specific problems with learning a certain route and building a cognitive map, which involve areas in the brain called the caudate and hippocampus, could be detected in pre-clinical Alzheimer’s. Pre-clinical Alzheimer’s is a stage in the disease where you already have it, but aren’t yet showing obvious symptoms.
In the study, 71 participants spent about two hours on a desktop computer being tested on their ability to navigate a virtual maze consisting of a series of interconnected hallways with four wallpaper patterns and 20 landmarks. Participants were tested on two navigation skills: how well they could learn and follow a pre-set route, and how well they could form and use a cognitive map of the environment. Participants were given 20 minutes to either learn a specified route, or to study and explore the maze with a navigation joystick. They were then tested on their ability to recreate the route or find their way to specific landmarks in the environment.
The experiment’s design played on the fact that humans generally find their way in life using two distinct forms of spatial representation and navigation. Egocentric navigation relies on past knowledge to follow well-worn routes, moving from one landmark to another until they reach their target destination. In allocentric navigation, people become familiar with their big picture surroundings and create a mental map of existing landmarks, allowing them to plot best available routes and find shortcuts to new destinations.
Researchers discovered that abilities in these types of navigation declined in people who then went on to develop Alzheimer’s disease. People experiencing memory lapses and other behavioural problems associated with early stage Alzheimer’s disease had clear difficulties both in learning an established route and in finding their own way to new landmarks.
‘These findings suggest that navigational tasks designed to assess a cognitive mapping strategy could represent a powerful new tool for detecting the very earliest Alzheimer’s disease-related changes in cognition,’ says senior study author Denise Head, associate professor of psychological and brain sciences in Arts & Sciences.
‘The spatial navigation task used in this study to assess cognitive map skills was more sensitive at detecting preclinical Alzheimer’s disease than the standard psychometric task of episodic memory,’ she said.