ISLAMABAD, April 26 (Online): The average human brain has been growing over the last century, according to research.
\nDementia is a growing problem worldwide, with numbers predicted to almost triple over the next 30 years.
\nThe rise is generally attributed to the growing and aging population, but lifestyle can also contribute.<\/p>\n
However, a new study suggests there may be some good news in the field of dementia.
\nIt found that people\u2019s brains have been getting larger over the past 100 years, and this increased brain reserve could, potentially, reduce the risk of age-related dementias.
\nAs healthy people get older, the brain decreases slightlyTrusted Source in size. However, in people with dementia, as nerve cells are damaged and die, many regions of the brain shrink, a process known as brain atrophy. So, could a larger brain help reduce a person\u2019s risk of dementia?<\/p>\n
A new study, from UC Davis Health, has suggested that it might. Researchers found that people born in the 1970s had brains that were, on average, 6.6% larger than those of people born in the 1930s. They suggest that larger brain size means increased brain reserve \u2014 which may reduce the risk of age-related dementias.<\/p>\n
The study is published in JAMA NeurologyTrusted Source.<\/p>\n
\u201cWhile these newly published results add to the body of literature on brain size and changes over time, this study was largely conducted in healthy, well-educated, non-Hispanic White individuals, and so [these findings] are not necessarily generalizable to other groups or individuals.\u201d<\/p>\n
\u2014 Ozama Ismail, PhD, Alzheimer\u2019s Association director of scientific programs, who was not involved in the study.<\/p>\n
Dementia\u2019s effects on the brain
\nCurrently, around 58 millionTrusted Source people worldwide have dementia, and that number is projected to reach 152.8 million by 2050.<\/p>\n
Although some memory loss is a natural part of aging, dementia is not. Dementia describes a range of diseases, with the most common, being Alzheimer\u2019s disease, causing 60-80% of cases. Others include vascular dementia, Lewy body dementia (which may be associated with Parkinson\u2019s disease), frontotemporal dementia, and mixed dementia.<\/p>\n
Symptoms of dementia, which worsen over time, may include:<\/p>\n
memory problems
\nasking the same question repeatedly
\ndifficulty finding or understanding words
\nfeeling confused in unfamiliar environments
\nproblems dealing with money and numbers
\nanxiety and withdrawal
\ndifficulty planning and carrying out tasks
\nmood, personality and behavior changes
\nsleep disturbances
\nobsessive tendencies
\nIn all types of dementia, as brain cells are damaged and die, there is some degree of brain shrinkageTrusted Source, with this being particularly pronounced in Alzheimer\u2019s disease and vascular dementia.<\/p>\n
Human brain sizes are increasing
\nThis study looked at participants in the Framingham Heart Study (FHS). This long-term study has followed 15,000 individuals for more than 75 years.<\/p>\n
Of the FHS cohort, 3,226 people had two MRI scans that were suitable for this study. Of them, 1,706 (53%) were women, and 1,520 (47%) were men. The scans measured intracranial volume (ICV), cortical gray matter, cerebral white matter, hippocampal volume, cortical surface area, and cortical thickness measures.<\/p>\n
The participants were all born between 1930 and 1970, with the median decade of birth being the 1950s. People born in the 1970s were, on average, 1.6 inches taller than those born in the 1930s, so the researchers adjusted for this when comparing brain measurements.<\/p>\n
People born in the 1970s had greater brain volumes than those born in the 1930s.<\/p>\n
They had a 6.6% greater ICV, 7.7% more white matter, 2.2% more cortical gray matter, 5.7% greater hippocampal volume, and 14.9% larger cortical surface area. The one measure that had decreased was cortical thickness, which was 20.9% lower. These differences remained significant when the researchers adjusted for height differences.<\/p>\n
\u201cThe decade someone is born appears to impact brain size and potentially long-term brain health,\u201d said Charles DeCarli, MD, first author of the study, distinguished professor of neurology, and director of the UC Davis Alzheimer\u2019s Disease Research Center in a press release.<\/p>\n
\u201cGenetics plays a major role in determining brain size, but our findings indicate external influences \u2014 such as health, social, cultural and educational factors \u2014 may also play a role,\u201d he said.<\/p>\n
\u201cLarger brain structures like those observed in our study may reflect improved brain development and improved brain health. A larger brain structure represents a larger brain reserve and may buffer the late-life effects of age-related brain diseases like Alzheimer\u2019s and related dementias.\u201d
\n\u2014 Charles DeCarli, MD<\/p>\n
Larger brain size may indicate lower dementia risk
\nPrevious studiesTrusted Source have suggested that larger brain volume protects against the effects of dementia pathology, arguing that those with a greater head circumference can endure a greater degree of damage before they start to show cognitive impairment.<\/p>\n
This \u2018brain reserve hypothesis\u2019Trusted Source suggests that a larger brain volume, with more neurons and synaptic connections, could provide protection against cognitive decline from brain atrophy. Experts use ICV on MRI and head circumference as indicators of brain volume.<\/p>\n
However, this observed effect could be due to other factors, as Ismail told Medical News Today:<\/p>\n
\u201cLarger brain volumes may be beneficial in maintaining resilience to cognitive decline and dementia, but many other factors can contribute to resilience, including genetics, environment, socioeconomic status, education, and active vs. sedentary lifestyle.\u201d<\/p>\n
Other studiesTrusted Source have stressed that cognitive reserve \u2014 how well the brain functions \u2014 is more important than actual brain size in relation to dementia risk. People with a higher cognitive reserve tend to show dementia symptoms later, but then decline faster once symptoms become evident.<\/p>\n
The researchers in this study suggest that the increase in brain volumes over the four birth decades in their study could predict a lower risk of dementia in people born later in the FHS.<\/p>\n
The researchers acknowledge that their study cohort was predominantly non-Hispanic White, healthy, and well-educated, so not representative of the general population of the United States. However, they emphasize that the strengths of the study include the fact that it has followed 3 generations, spanning more than 80 years of births.<\/p>\n
Ismail called for further studies that include a greater diversity of people:<\/p>\n
\u201cMore diversity in research populations is needed before conclusions can be made about changes in brain size over generations and the influence it may have on cognition, resilience, and dementia risk.\u201d<\/p>\n
\u201cThis is particularly important given the known sociocultural and health disparities that exist in underrepresented populations,\u201d he added.<\/p>\n
The Alzheimer\u2019s Association\u2019s U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER), which should publish results next year, aims to help address this gap in the research, as Ismail told MNT:<\/p>\n
\u201cIn the U.S. POINTER Study, more than 2,000 volunteer older adults who are at increased risk for cognitive decline are enrolled and will be followed for two years. Nearly 30% of current participants are from populations historically underrepresented in Alzheimer\u2019s\/dementia research.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"
ISLAMABAD, April 26 (Online): The average human brain has been growing over the last century, according to research. Dementia is a growing problem worldwide, with numbers predicted to almost triple over the next 30 years. The rise is generally attributed to the growing and aging […]<\/p>\n
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