Mobile game detects Alzheimer's risk
A specially designed mobile phone game called Sea Hero Quest has found that gaming data can distinguish between those people who are genetically at risk of developing Alzheimer's disease ond those who are not. The game is designed to test spatial navigation skills — one of the first cognitive areas affected in Alzheimer's.
A standard memory and thinking test could not distinguish between the risk and non-risk groups.
Gaming data was taken from 27,108 UK players aged 50-75. This benchmark data was then compared with 60 people who had been genetically tested, of whom about half carried the APOE4 gene. The gene tested individuals were matched for age, gender, education and nationality with the benchmark cohort.
Previous findings from Sea Hero Quest data have shown that people in different countries and populations navigate differently, but this study shows that APOE4 carriers took less efficient (i.e., longer) routes to checkpoint goals. The difference in performance between carriers and non-carriers was particularly pronounced where the space to navigate was large and open.
Getting lost may be the first sign of Alzheimer’s
Preliminary findings from a long-term UK study indicate that middle-aged adults (41-59) with close relatives with Alzheimer's did worse on a test that measured their ability to visualise their position. They also tended to have a small hippocampus.
The Four Mountains test involves showing people a picture of a mountain and asking them to identify it in a selection of four other landscapes.
Building mental maps precedes route navigation problems
A study involving 71 older adults found that increasing difficulties with building cognitive maps of new surroundings was associated with the development of Alzheimer's biomarkers. Difficulties in learning a new route were not evident at this stage, but appeared later, among those with early Alzheimer's.
The computer task involved navigating 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.
Humans generally find their way using two distinct forms of spatial representation and navigation: egocentric navigation, in which people rely on past knowledge to follow well-worn routes, moving from one landmark to another, and allocentric navigation, in which 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. Allocentric navigation relies on the hippocampus, while egocentric navigation is more closely associated with a brain region called the caudate.
Those with cerebrospinal markers for Alzheimer’s but no symptoms, had significant difficulties only when they had to form a cognitive map (that is, with hippocampal allocentric navigation processes). However, additional training did enable them to eventually learn the cognitive map.
The researchers suggest that preclinical Alzheimer’s disease is characterized by hippocampal atrophy and associated cognitive mapping difficulties, and then, (if) the disease progresses, cognitive mapping deficits worsen, the caudate becomes involved, leading to route learning deficits.
Participants included 42 who were cognitively healthy and had no cerebrospinal fluid markers for Alzheimer’s, 13 cognitively normal individuals who had the biomarkers, and 16 with early Alzheimer’s.
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