The World Health Organization has released the second edition of its guidelines on reducing the risk of cognitive decline and dementia, adding seven new health conditions and exposures to its list of modifiable risk factors. The update, which revises the original 2019 report, reflects what the agency describes as the latest evidence and advances in dementia risk reduction.
The newly added risk factors include vision loss, high LDL cholesterol, and untreated HIV, alongside other conditions that have emerged in recent research. These join the original 12 risk factors from the 2019 edition, which covered areas such as physical inactivity, smoking, excessive alcohol consumption, diabetes, hypertension, obesity, depression, and social isolation.
Dr. Daniel Amen, a physician and founder of Amen Clinics in California, spoke about the additions, noting that several of them point to broader connections between brain health and overall physical health. Among the new factors, vision impairment stands out because a significant portion of the brain is dedicated to visual processing. According to Amen, when vision becomes troubled, the brain becomes troubled, as the condition places additional demands on cognitive resources. The WHO notes, however, that there is insufficient evidence to recommend vision treatment specifically for dementia prevention.
The guidelines also address menopause-related hormone therapy. The WHO does not recommend menopausal hormone therapy specifically to prevent dementia in postmenopausal women aged 65 and older. For younger women, the agency says there is not enough evidence to determine whether such therapy affects dementia risk. Amen agreed that the evidence is insufficient to support using hormone therapy solely for dementia prevention, though he noted that hormonal changes during menopause can affect mood and memory. Lower progesterone can make women anxious, and lower estrogen can contribute to memory problems, he said, adding that early hormone replacement can be helpful based on brain imaging work.
Cardiovascular health features prominently in the updated guidance. Conditions that affect the heart and blood vessels, including heart disease, heart rhythm problems, stroke, and transient ischemic attacks, are associated with a higher risk of dementia. Erectile dysfunction, which can signal underlying vascular disease, is also included. Amen pointed out that the condition is common, affecting 40 percent of 40-year-olds and 70 percent of 70-year-olds, framing brain health as connected to broader quality-of-life concerns.
Head trauma is another addition that Amen said the WHO has been slow to emphasize. Traumatic brain injury can range from a mild concussion to severe injury, and even mild cases can have lasting consequences. Amen described seeing patients who developed depression, anxiety, or temper problems after accidents in their 30s, with the root cause being an earlier brain injury. He stressed the importance of protecting the brain, which he described as very soft, with the consistency of soft butter.
Sleep is also highlighted in the updated guidelines. Sleep challenges affect tens of millions of Americans, and CDC data from 2024 shows that 30.5 percent of U.S. adults reported getting less than seven hours of sleep per night. Amen noted that sleep supports the brain's waste-clearance processes, and research suggests it helps clear beta-amyloid, a protein associated with Alzheimer's disease. Sleep apnea, in particular, can cause brain changes that resemble the hallmarks of the disease, though the relationship between sleep and dementia remains complex and is still being studied.
Inflammation and infections round out the new additions. Untreated HIV can affect the central nervous system and is associated with HIV-related cognitive impairment, though effective antiretroviral therapy has greatly reduced the incidence of severe HIV-associated dementia. Exposure to toxins, including alcohol, marijuana, lead, mercury, and air pollution, is also flagged. The WHO recommends reducing exposure to household and outdoor air pollution, particularly fine particulate matter, though it characterizes the evidence linking air pollution to dementia as low to very low certainty.
Dementia risk rises sharply with age. A recent U.S. analysis estimated that about one in five people had developed dementia by age 85, with risk increasing further at older ages. While genetic predisposition plays a role, Amen emphasized that lifestyle factors can increase risk for anyone, making the WHO's updated guidance a practical tool for prevention.