The Wisconsin Registry for Alzheimer’s Prevention, a study of 1,500 people ages 45 to 75, started at UW-Madison in 2001. About 1,000 participants have at least one parent with Alzheimer’s, putting them at greater risk for the disease. The others, who don’t have a family history, serve as a control group.

Summaries of recent findings from the study:

• Genetic risk: People with a mutation in a gene called TOMM40 have less-desirable gray matter in parts of the brain affected by Alzheimer’s and score lower on verbal recall tests. TOMM40 could be an important Alzheimer’s risk gene, joining APOE4, the main genetic risk marker identified years ago.

• Game playing: Cognitive activities, such as playing cards and board games or doing crossword puzzles, appear to help preserve brain function in midlife. Such activities may be more important than education level in reducing the risk of Alzheimer’s.

• Word recall: After hearing 15 unrelated nouns, children of people with Alzheimer’s listed an average of 10 of the words. So did the controls. But the first group was more likely to name words toward the end of the list. A reliance on immediate memory, present in people diagnosed with Alzheimer’s, could become a test for the disease.

• Brain shrinkage: The hippocampuses of children of people with Alzheimer’s shrunk more than those of controls over four years, according to MRI scans. Brain changes caused by Alzheimer’s might be detectable before people show any signs. “Like heart disease, this process begins long before someone becomes symptomatic,” said Dr. Mark Sager, director of WRAP until he retired last month.

• Brain blood flow: People whose mother had Alzheimer’s have decreased blood flow in parts of the brain associated with the disease, compared to people whose father had Alzheimer’s and people with no affected parent, MRI scans showed. Other studies also suggest a maternal history of Alzheimer’s is an especially important risk factor.

• Insulin resistance: People with insulin resistance, the impaired processing of glucose associated with diabetes, have less gray matter in parts of the brain associated with Alzheimer’s. The areas shrunk more than average over four years, corresponding with less ability to recall words.

• Stress: Among children of people with Alzheimer’s, those reporting more stressful events the past year scored lower on tests of speed and flexibility. Those who reported greater social support scored higher. “Psychosocial factors may influence cognition in at-risk individuals,” the researchers said.