As people age, we naturally have a harder time recalling our memories. However, a condition that typically arises later in life, called dementia, can cause more severe memory decline. Dementia can impact our quality of life by making it difficult to remember essential information, like our age, phone number, home address, or the names of loved ones. There is no cure for dementia, but researchers have explored the impacts of various lifestyle choices on the risk of developing it.
One team of researchers recently analyzed the impact of diet on individuals who were susceptible to developing dementia and depression. These researchers previously found that both dementia and depression are related to brain cells forming in a region responsible for creating new memories, called the hippocampus. This process is known as hippocampal-neurogenesis, and issues with it, including cells dying at increasingly high rates, can worsen someone’s risk of dementia and depression. The researchers referred to a genetic predisposition in people who have trouble with hippocampal-neurogenesis by a term they coined neurogenesis-centered biological susceptibility.
The researchers wanted to determine whether one’s diet impacts hippocampal neurogenesis. They looked for either an increased or reduced risk of dementia and depression depending on what participants ate. Other dementia researchers have focused primarily on whether the Mediterranean diet reduced one’s risk of dementia. By contrast, these researchers focused on the connection between several vitamins and food groups and hippocampal neurogenesis susceptibility to the following conditions: Alzheimer’s disease, vascular and other types of dementia, depression, and general cognitive decline.
The team worked with 371 individuals without dementia, with an average age of 76 at the start of the trial. First, researchers obtained a blood sample from each participant to assess their nutrient levels. Then, they used information from the blood samples to identify those who met the criteria for neurogenesis-centered biological susceptibility and those who did not. Finally, they recorded the participants’ medical histories and noted their medications.
After they collected this initial information, they met with participants every 2 years over 12 years. They interviewed them about their diets at the first 2-year follow-up visit. They also monitored their mental abilities and emotional states at each visit. During the 12 years, 21% of the participants developed dementia, and 29% of them experienced depression-related symptoms.
After the 12-year trial, the researchers evaluated how each participant’s diet affected their risk of developing Alzheimer’s, vascular dementia, or depression. They quantified the risk using a statistical measure known as an odds ratio, where an odds ratio above 1 meant that individuals had an increased risk of developing these conditions, and an odds ratio below 1 meant they had a reduced risk. They found that susceptible participants who reported diets with higher amounts of poultry, such as chicken or turkey, had an odds ratio of 0.9, or reduced risk, for Alzheimer’s. Whereas susceptible individuals who reported diets consisting of high amounts of red meat, such as beef or pork, had an odds ratio of 1.1, or increased risk, for Alzheimer’s.
The scientists also found that susceptible participants who consumed high amounts of vitamin D, found in fatty fish, fortified milk, and cereal grains, had an odds ratio of 1.05, or increased risk, for vascular dementia. They discovered that susceptible individuals who consumed higher amounts of a form of vitamin E found in whole grains, leafy greens, and nuts, called γ-tocopherol, had an odds ratio of 1.08, or increased risk, for depression. However, researchers noted that diet had no impact on whether individuals would experience natural cognitive decline, nor did it impact the risk of dementia in those who were not susceptible to it.
The scientists concluded that eating more poultry than red meat may reduce the risk of Alzheimer’s disease in individuals with neurogenesis-centered biological susceptibility. However, they did not expect vitamins D and E to increase one’s risk of dementia and depression, respectively, since these vitamins should benefit human health. Regardless of these nuances, the researchers suggested that understanding the connection between meat consumption and Alzheimer’s may improve late-in-life health for people predisposed to it.
