Of all the common consequences of aging, none is more frightening than memory loss. Even if you’ve never helplessly watched a loved one succumb to Alzheimer’s—which I promise is worse than it sounds—it’s natural to wonder if something similar could happen to you.
Our collective fear of aging has long been exploited for profit; cognitive decline is no exception. Most people are terrified of losing their mental faculties as they age, and corporations know it—brain power-boosting games and apps are a big business these days. Their claims are bold: Lumosity promises to help users “improve memory, increase focus, and find calm.” 2013 Apple App of the Year winner Elevate touts itself as “a brain training program designed to improve focus, speaking abilities, processing speed, memory, math skills, and more.” Using fear to sell products may be an effective marketing strategy, but those products rarely solve any actual problems.
There’s so much about dementia that we still don’t know, but one thing is certain: it’s caused by a complex confluence of many, many factors. In other words, any single prevention-minded strategy—like playing a game on your phone for a few minutes a day—probably won’t make a difference, but a multi-pronged approach just might. While the majority of risk factors are beyond our control, some of them are within our power to change, and knowing the difference is your best protection.
What is dementia, and what causes it?
There are three main types of memory loss: age-related cognitive decline, mild cognitive impairment (MCI), and dementia. Although the symptoms overlap somewhat, these are distinct conditions and it’s important to know the differences between them.
Age-related cognitive decline
Age-related cognitive decline is what we call the somewhat normal level of memory loss. Just like our hair, skin, and muscles, brain cells age along with us, which can cause impaired cell function and communication. Everyone loses some neurons as a normal part of the aging process, so mild memory problems can be chalked up to getting older.
Mild cognitive impairment
MCI lies between normal aging and dementia on the severity scale. People with MCI have more memory problems than is considered normal for their age group, but can still function on their own. (As always, determining what’s “normal” is at the discretion of a qualified medical professional.) It makes accomplishing day-to-day tasks more difficult, like remembering appointments and medications, but unlike dementia, MCI typically doesn’t cause behavioral changes.
Dementia, according to the National Institute on Aging, is “the loss of cognitive functioning—thinking, remembering, and reasoning—and behavioral abilities to such an extent that it interferes with a person’s daily life and activities.” People with dementia forget appointments and medications, but they can also experience impaired vision, language skills, spatial reasoning, and decision-making. They may wander or get lost. Dementia can eventually cause personality changes: irritability, paranoia, hallucinations, aggression, unusual sexual behavior, and even physical violence.
The most common cause of dementia is Alzheimer’s disease, which can be either early- or late-onset. In late-onset Alzheimer’s, the more common type, dementia symptoms set in during or after the mid to late 60s. Early-onset Alzheimer’s is rarer, accounting for roughly 10 percent of all cases, and sets in anytime between age 30 and 60.
Scientists don’t fully understand why dementia develops, but in general, cognitive issues arise when neurons stop communicating with other brain cells and eventually die. In Alzheimer’s disease specifically, amyloid proteins and neurofibrillary (or tau) fibers clump together in abnormal formations, interrupting neuron connections and killing formerly healthy tissue. These formations, called amyloid plaques and tau tangles, are believed to at least partially explain the cognitive and behavioral changes observed in Alzheimer’s patients. The areas of the brain involved with memory are the usually first to be damaged, causing forgetfulness and broader memory loss; as the disease progresses to other parts of the brain, the patient gradually loses their ability to reason, speak, and behave normally. Eventually, the damage becomes so widespread that it affects basic physical functions like breathing and swallowing.
Who’s at risk?
The exact physiological causes of dementia are largely unknown, which makes early detection all but impossible; if there’s a precursor that shows up in routine blood work or imaging, we haven’t found it yet. For most people, dementia symptoms are their only warning, so it’s important to know your risk.
The single biggest risk factor for dementia is age. Whether it’s caused by Alzheimer’s or something else, dementia is much more common in the elderly; the NIH estimates that half of people over age 85 have some form of dementia. Family history also plays a role. Some people with no family history at all develop dementia, but as with many other medical conditions, the more people in your family that have had it, the higher your risk. Additionally, mental illness, particularly depression, is associated with an increased risk of developing dementia.
Both early- and late-onset Alzheimer’s have a genetic component, but that doesn’t mean you evaluate your risk with a DNA test—it just means that researchers have identified some of the chromosomes and genetic mutations involved in Alzheimer’s development. Your genes are just a few of many factors at play in a complex, decades-long process; plenty of Alzheimer’s patients don’t have any of the relevant mutations at all. It is worth noting, though, that most people with Down syndrome will develop Alzheimer’s. This could be because the gene that produces amyloid proteins is located on chromosome 21, of which people with Down syndrome have an extra copy.
What can we do about It?
There’s no sugarcoating this: Dementia cannot currently be prevented, and there’s no way to stop, reverse, or slow its progression. Finding a cure is a top priority, but the ultimate goal of dementia research is to prevent it altogether—ideally through easily-adopted lifestyle changes. Scientists have explored several interventions that could delay the onset of cognitive decline, but only some of them are truly promising.
Exercise may help, but we’re not sure
Of all the potential interventions, none have been studied more than exercise. The results are mostly inconclusive. While some studies suggest that increased physical activity may delay normal age-related cognitive decline, there’s no evidence that the same is true for MCI or dementia. Still, staying physically active has enough general health benefits that it’s worth your time—it’s just not the one thing that’ll keep you from developing dementia.
Brain training games may not improve your brain in real life
Another increasingly popular intervention is “cognitive training,” or playing increasingly difficult games to challenge different parts of your brain. It’s an attractive idea: play enough games and solve enough puzzles and you, too, can improve your overall cognition. Unfortunately, the research doesn’t quite back it up. Some games show more promise than others, but for the most part, brain training seems to mostly improve your ability to play that specific game.
For cognitive training to work, any benefits gained from playing games should carry over into related tasks in what’s known as a “transfer effect.” Proving this is way harder than it sounds: scientists disagree about which aspects of cognition correspond to brain training games, as well as how to meaningfully test for improvement. As a result, very few researchers have observed transfer effects. That hasn’t stopped corporations like Lumosity from claiming otherwise, even though there’s no proof these games can stave off cognitive decline. (Lumosity was fined $2 million by the FTC in 2016 for “deceptive advertising charges.”)
Treating high blood pressure may help
Something that could be more helpful is aggressive hypertension treatment, which just means bringing your blood pressure into the normal range—120/80 mmHg or less. A recent randomized clinical trial of more than 9000 hypertensive adults found a connection between intensive blood pressure management and the risk of MCI and probable dementia: people who reduced their systolic blood pressure to 120 mmHg or lower had a significantly lower rate of MCI than those whose systolic pressure was under 140 mmHG (14.6 vs 18.3 cases per 1000 person-years, respectively). Intensive blood pressure reduction also significantly reduced the combined risk of MCI and dementia. As for probable dementia on its own, researchers observed a measurable reduction—7.2 vs 8.6 cases per 1000 person-years for the 120 mmHg and 140 mmHG groups, respectively—but it was not statistically significant.
That doesn’t mean this study is bunk; quite the opposite, actually. It’s the first large-scale randomized clinical trial to find a statistically meaningful link between a common, treatable physical condition and the risk of MCI. On top of that, the study was so successful at reducing cardiovascular events and overall mortality that the blood pressure management program ended after 3.3 years—more than a year and a half early. MCI and dementia assessment continued for the full five years. Given the participants’ relative youth (about 68 years on average), the short observation window, and the fact that MCI usually presents earlier than dementia, it makes sense that significant results were only observed in relation to MCI—and therefore pretty exciting that any dementia result was observed at all. It’s always possible that future research will contradict these findings, but until then, it seems like as good a reason as any to keep your blood pressure under control.
Social interaction is our most promising strategy so far
Finally, and perhaps most promisingly, there is mounting evidence that social isolation is a major risk factor for cognitive decline and dementia. A 2017 Lancet Commission report estimates that social isolation accounts for up to 2 percent of lifetime dementia risk—just as much as hypertension. Though it’s a relatively new area of research, more and more studies are exploring the intervention potential of increased socialization. To learn more, I spoke with the author of one of these studies: Dr. Hiroko Dodge, principal investigator of Oregon Health & Science University’s I-CONECT project.
In a June 2015 Alzheimer’s & Dementia paper, Dr. Dodge et. al. designed a clinical trial to test the effect of “naturalistic human contact” on cognitive function in elderly (80 years, on average) adults. About half of the participants video-chatted with trained interviewers 30 minutes a day for six weeks; the others did not. Compared with baseline scores and the control group, the video chatters showed improvement in semantic fluency (being able to find and produce words in a certain category) and psychomotor speed (reaction time). The only statistically significant results were observed in subjects with normal cognition—i.e., no impairment or dementia—but subjects with MCI still showed improvement relative to controls. The study was considered a success, and a larger-scale follow-up trial is currently ongoing.
Dr. Dodge believes that the human element of video chat is key to their observed results. In the conversation sessions, interviewers were trained to prioritize eye contact and back-and-forth conversation, two important aspects of face-to-face contact that socially isolated people don’t get enough of. Plus, video chat is accessible to the people who stand to benefit from it the most: physically and socially isolated adults. I asked Dr. Dodge if FaceTiming or video chatting with isolated elderly relatives was a good thing to do regularly. “Definitely,” she said, explaining that regular face-to-face conversations could improve cognitive compensation mechanisms—the brain’s ability to work around cognitive impairments.
Of course, a cure or prevention for dementia is a ways off. The NIH calls clinical trials the “gold standard” of medical proof, but getting statistically significant results out of them is exceptionally difficult. As Dr. Dodge explained to me, this is because variability is very high in dementia research, particularly where human subjects are concerned:
“If you ask [subjects] in the morning to do tests, and then in the afternoon to do tests, even within an individual the fluctuation is so high. … When they’re feeling good, or if they slept well last night, they do much better. If they didn’t sleep well, or if they have a little cold, that really shifts around the scores.”
She also mentioned that cognitive compensation complicates things further: people with the same degree of cognitive impairment can perform differently on tests depending on how (or if) they’ve learned to cope with it.
Social isolation research is promising, but it’s just beginning—and until it studies more people of different ages, ethnicities, nationalities, genders, and socioeconomic classes, we won’t know for sure just how much it can help.
Taken together, the body of research on dementia intervention suggests that staying socially and physically active is our best bet for long, healthy lives. However, as Dr. Dodge reminded me, you can do everything “right” and still get dementia—so we have got to stop blaming people for failing to prevent an unpreventable disease. “If somebody gets dementia, others may say, ‘Oh, she didn’t do social interaction, or she didn’t do cognitive stimulation’ … unfortunately, some people will get the disease, and it’s not their fault.”