Oct 31st 2014

Aging brains aren't necessarily declining brains

For years, conventional wisdom held that growing older tends to be bad news for brains. Past behavioral data largely pointed to loss in cognitive – that is, thinking – abilities with age, including poorer memory and greater distractibility. Physical measures of brain structure also showed atrophy, or loss of volume, in many regions with age.

Watching older brains at work

Enter cognitive neuroscience, a subfield of psychology that incorporates methods from neuroscience. It uses measures of brain activity to understand human thought. The emphasis is on how the brain shapes behavior, asking questions like which brain regions help us form accurate memories or what area controls face perception.

Using cognitive neuroscience methods to study aging has unexpectedly revealed that, contrary to previous thought, aging brains remain somewhat malleable and plastic. Plasticity refers to the ability to flexibly recruit different areas of the brain to do different jobs. In contrast to the earlier, largely pessimistic view of aging, neuroimaging studies suggest aging brains can reorganize and change, and not necessarily for the worse.

fMRI scan shows areas of brain more active than others. John Graner, Walter Reed National Military Medical Center

Researchers investigate which parts of the brain are engaged during different tasks using methods such as functional magnetic resonance imaging, which measures blood flow to various areas of the brain while active. By tracking what happens inside the brain during particular activities, neuroimaging data reveal patterns of change with age. For instance, older adults sometimes use a region in both the left and right hemispheres of their brains to perform certain tasks, while young adults engage the region in only one half of the brain. Older adults also appear to activate more anterior regions of the brain whereas young adults exhibit more posterior activation.

The emergence of the cognitive neuroscience of aging occurred alongside advances in the understanding of neurogenesis; neuroscientists discovered that the growth of new neurons could continue throughout life, not just when we are very young. It is still unknown to what extent new neurons contribute to behavioral and brain changes with age. But there is some evidence in rodents that new learning and enriched, stimulating environments increase survival of new neurons potentially allowing the new neurons to contribute to abilities and even improve health.

External stimulation

Stimulating the left side of his brain generates movement in the right hand. Eric Wassermann, M.D., CC BY

One exciting new direction for research on the aging brain uses neurostimulation to temporarily activate or suppress distinct neural regions. With transcranial magnetic stimulation, a coil is held over a participant’s head. Participants may be able to feel some stimulation on the scalp when the coil is turned on. Transcranial direct current stimulation is an even more surprising technique, with current administered from a 9V battery. These methods are non-invasive, simply involving holding a device over a person’s head or attaching electrodes to the scalp, and are quite safe when operated within guidelines.

They allow us, for the first time, to manipulate brain activity in a healthy, functioning person. Other neuroscience methods allow neurons to be turned on or turned off using pharmacological, genetic, or other methods, but such manipulations can’t ethically be applied to humans. While neuroimaging methods allow us to view which brain regions are active while performing cognitive tasks, we haven’t been able to test whether those brain regions cause, or are critical for, those tasks.

Shocking results! Older subjects did almost as well as young ones when their brains were direct current stimulated. Science/AAAS, Author provided

The ability to manipulate brain regions – temporarily and safely – allows for new types of tests that couldn’t be done before. For example, stimulating the frontal cortex – the brain region behind the forehead – can decrease errors on cognitive tests. When older adults in one study were asked to give examples of items that fit into different categories, they made mistakes under time pressure. Administering transcranial direct current stimulation decreased the number of errors committed by older adults, bringing them close to the level of performance of younger adults.

Neurostimulation offers much promise to further understanding of how the brain works in aging people, but there are many limitations. The spatial area affected by neurostimulation is not very precise as the scientist passes the coil over the subject’s head. Many regions cannot be targeted because they’re located deep within the brain, particularly problematic for studying memory. And activating some regions can cause discomfort for participants, such as twitching induced in the area of the forehead.

It’s not all downhill

Much of our understanding of aging brains has thus far focused on declining cognitive abilities. But there is some evidence that social and emotional abilities are relatively well-preserved with age. Older adults seem to be just as good at forming impressions of others and are even better at regulating or controlling their emotions than younger adults.

This suggests that brain regions underlying these abilities may not exhibit the same downward trajectory with age as those associated with cognitive abilities; these brain areas may show different patterns of reorganization and change.

Should these abilities be better preserved with age, they could be harnessed to develop effective memory strategies. For instance, emphasizing the motivational, personal and emotional significance of information to be remembered could help older people’s memories. Much research remains to be done on these questions.

Active older brain, healthy older brain? Men image via www.shutterstock.com

Brain workouts

Older brains' plasticity suggests they could benefit from training programs and engaging, immersive experiences such as learning new skills like quilting or digital photography. Such a finding would have profound implications for the large population of active seniors who wish to stave off age-related cognitive decline.

While research is flourishing on a number of potential programs that could positively affect brain health – including physical exercise, cognitive regimens and engaged, social lifestyles – caution is warranted. For example, researchers warn there is little scientific evidence of the effectiveness of brain training software – so-called brain games – to date.

The aging brain has proven to be much more dynamic than early research would have suggested. Advances in research methods and widening the range of questions under investigation will further enhance our understanding of how the brain changes and adapts across the lifespan. With luck, this knowledge will reveal ways to harness plasticity to better support cognition as we age.

The Conversation

Angela Gutchess has current funding from NSF and the Alzheimer's Association. Past funding was received from NIH and AFAR.

This article was originally published on The Conversation. Read the original article.

Browse articles by author

More Current Affairs

Mar 18th 2024
EXTRACT: "....the UK’s current economic woes – falling exports, slowing growth, low productivity, high taxes, and strained public finances – underscore the urgency of confronting Brexit’s catastrophic consequences."
Mar 18th 2024
EXTRACTS: Most significant of all, Russia’s Black Sea fleet has suffered significant losses over the past two years. As a result of these Ukrainian successes, the Kremlin decided to relocate the Black Sea fleet from Sevastopol to Novorossiysk on the Russian mainland. Compare that with the situation prior to the annexation of Crimea in 2014 when Russia had a secure lease on the naval base of Sevastopol until 2042." --- "Ukrainian efforts have clearly demonstrated, however, that the Kremlin’s, and Putin’s personal, commitment may not be enough to secure Russia’s hold forever. Kyiv’s western partners would do well to remember that among the spreading gloom over the trajectory of the war."
Mar 8th 2024
EXTRACT: "As the saying goes, 'It’s the economy, stupid.' Trump’s proposed economic-policy agenda is now the greatest threat to economies and markets around the world."
Mar 8th 2024
EXTRACT: "Russia, of course, brought all these problems on itself. It most certainly is not winning the war, either militarily or on the economic front. Ukraine is recovering from the initial shock, and if robust foreign assistance continues, it will have an upper hand in the war of attrition."
Mar 8th 2024
EXTRACT: "...... with good timing and good luck, enabled Trump to defeat [in 2016] political icon Hillary Clinton in a race that appeared tailor-made for her. But contrary to what Trump might claim, his victory was extremely narrow. In fact, he lost the popular vote by 2.8 million votes – a larger margin than any other US president in history. Since then, Trump has proved toxic at the ballot box. " -----"The old wisdom that 'demographics is destiny' – coined by the French philosopher Auguste Comte – may well be more relevant to the outcome than it has been to any previous presidential election. "----- "Between the 2016 and 2024 elections, some 20 million older voters will have died, and about 32 million younger Americans will have reached voting age. Many young voters disdain both parties, and Republicans are actively recruiting (mostly white men) on college campuses. But the issues that are dearest to Gen Z’s heart – such as reproductive rights, democracy, and the environment – will keep most of them voting Democratic."
Mar 8th 2024
EXTRACTS: "How can America’s fundamentalist Christians be so enthusiastic about so thoroughly un-Christian a politician?" ---- "If you see and think outside the hermeneutic code of Christian fundamentalism, you might be forgiven for viewing Trump as a ruthless, wholly self-interested man intent on maximizing power, wealth, and carnal pleasure. What your spiritual blindness prevents you from seeing is how the Holy Spirit uses him – channeling the 'secret power of lawlessness,' as the Book of 2 Thessalonians describes it – to restrain the advent of ultimate evil, or to produce something immeasurably greater: the eschaton (end of history), when the messiah comes again."
Mar 1st 2024
EXTRACT: "The lesson is that laws and regulatory structures are critical to state activities that produce local-level benefits. If citizens are to push for reforms and interventions that increase efficiency, promote inclusion, and enable entrepreneurship, innovation, and long-term growth, they need to recognize this. The kind of effective civil society Nilekani envisions thus requires civic engagement, empowerment, and education, including an understanding of the rights and responsibilities implied by citizenship."
Feb 9th 2024
EXTRACT: "Despite the widespread belief that the global economy is headed for a soft landing, recent trends offer little cause for optimism."
Feb 9th 2024
EXTRACT: " Consider, for example, the ongoing revolution in robotics and automation, which will soon lead to the development of robots with human-like features that can learn and multitask the way we do. Or consider what AI will do for biotech, medicine, and ultimately human health and lifespans. No less intriguing are the developments in quantum computing, which will eventually merge with AI to produce advanced cryptography and cybersecurity applications."
Feb 9th 2024
EXTRACTS: "The implication is clear. If Hamas is toppled, and there is no legitimate Palestinian political authority capable of filling the vacuum it leaves behind, Israel will probably find itself in a new kind of hell." ----- "As long as the PLO fails to co-opt Hamas into the political process, it will be impossible to establish a legitimate Palestinian government in post-conflict Gaza, let alone achieve the dream of Palestinian statehood. This is bad news for both Israelis and Palestinians. But it serves Netanyahu and his coalition of extremists just fine."
Jan 28th 2024
EXTRACTS: "According to estimates by the United Nations, China’s working-age population peaked in 2015 and will decline by nearly 220 million by 2049. Basic economics tells us that maintaining steady GDP growth with fewer workers requires extracting more value-added from each one, meaning that productivity growth is vital. But with China now drawing more support from low-productivity state-owned enterprises, and with the higher-productivity private sector remaining under intense regulatory pressure, the prospects for an acceleration of productivity growth appear dim."
Jan 28th 2024
EXTRACT: "When Chamberlain negotiated the notorious Munich agreement with Hitler in September 1938, The Times did not oppose the transfer of the Sudetenland to Germany without Czech consent. Instead, Britain’s most prestigious establishment broadsheet declared that: “The volume of applause for Mr Chamberlain, which continues to grow throughout the globe, registers a popular judgement that neither politicians nor historians are likely to reverse.” "
Jan 4th 2024
EXTRACTS: "Another Trump presidency, however, represents the greatest threat to global stability, because the fate of liberal democracy would be entrusted to a leader who attacks its fundamental principles." ------"While European countries have relied too heavily on US security guarantees, America has been the greatest beneficiary of the post-war political and economic order. By persuading much of the world to embrace the principles of liberal democracy (at least rhetorically), the US expanded its global influence and established itself as the world’s “shining city on a hill.” Given China and Russia’s growing assertiveness, it is not an exaggeration to say that the rules-based international order might not survive a second Trump term."
Dec 28th 2023
EXTRACT: "For the most vulnerable countries, we must create conditions that enable them to finance their climate-change mitigation" ........ "The results are already there: in two years, following the initiative we took in Paris in the spring of 2021, we have released over $100 billion in special drawing rights (SDRs, the International Monetary Fund’s reserve asset) for vulnerable countries.By activating this “dormant asset,” we are extending 20-year loans at near-zero interest rates to finance climate action and pandemic preparedness in the poorest countries. We have begun to change debt rules to suspend payments for such countries, should a climate shock occur. And we have changed the mandate of multilateral development banks, such as the World Bank, so that they take more risks and mobilize more private money."
Dec 27th 2023
EXTRACT: "....if AI causes truly catastrophic increases in inequality – say, if the top 1% were to receive all pretax income – there might be limits to what tax reforms could accomplish. Consider a country where the top 1% earns 20% of pretax income – roughly the current world average. If, owing to AI, this group eventually received all pretax income, it would need to be taxed at a rate of 80%, with the revenue redistributed as tax credits to the 99%, just to achieve today’s pretax income distribution; funding the government and achieving today’s post-tax income distribution would require an even higher rate. Given that such high rates could discourage work, we would likely have to settle for partial inequality insurance, analogous to having a deductible on a conventional insurance policy to reduce moral hazard."
Dec 21st 2023
EXTRACT: "Shocks are here to stay, and our task is not to predict the next one – although someone always does – but to sharpen our focus on resilience. Staying the course of politically mandated policies while minimizing the inevitable dislocations is easier said than done. But that is no excuse to fall for the myth of being victimized by the unprecedented."
Dec 21st 2023
EXTRACTS: "A new world is indeed emerging. It will be characterized not only by more interdependencies, but also by more insecurity, danger, and war. Stability in international relations will become a foreign concept from a bygone age – one that we did not fully appreciate until it was gone."
Dec 14th 2023
EXTRACT: "Yet one must never forget that Putin is first and foremost an intelligence officer whose dominant trait is suspicion."
Dec 2nd 2023
EXTRACTS: "In a recent commentary for the Financial Times, Martin Wolf trots out the specter of a 'public-debt disaster,' that recurrent staple of bond-market chatter. The essence of his argument is that since debt-to-GDP ratios are high, and eminent authorities are alarmed, 'fiscal crises' in the form of debt defaults or inflation “loom. And that means something must be done.' ----- "If, as Wolf fears, 'real interest rates might be permanently higher than they used to be,' the culprit is monetary policy, and the real risk is not rich-country public-debt defaults or inflation. It is recession, bankruptcies, and unemployment, along with inflation." ---- "Wolf surely knows that the proper remedy is for rich-country central banks to bring interest rates back down. Yet he doesn’t want to say it. He seems to be caught up, possibly against his better judgment, in bond vigilantes’ evergreen campaign against the remnants of the welfare state."
Nov 27th 2023
EXTRACT: "The first Russia, comprising those living in Russia’s two biggest cities, Moscow and Saint Petersburg, can pretend there is no war at all." ---- "Then there is the other Russia, the one you find in small towns and villages scattered across the country’s massive territory. Here, the Ukraine war is a source of patriotic pride,"