Cognitive Aging & Cognitive Reserve

Story

Connected to · 5

regulates · 3

Immune Aging & Inflammaging
The chronic low-grade inflammation of an aging immune system is linked with cognitive decline and is thought to be one of its drivers. It is not the only cause, and it is intertwined with vascular and metabolic factors.
Bacopa monnieri
Bacopa is thought to work by slowly changing the structure of neurons (in animal studies, hippocampal neurons grew more dendritic branches), which is why it takes about 12 weeks of daily use before any signal appears, and a single dose tested two hours later shows nothing. The positive results land on only two things, how fast you learn a list of new words and how fast you process information, and the effects are small; short-term attention and working memory show no difference on repeated testing.
Neurovascular coupling
When activity rises in part of the brain, neurons, glial cells and blood vessels work together to send more blood there; this is called neurovascular coupling. Some researchers propose that with age the small arteries respond to these signals more slowly, so local blood flow lags, and the long, thin nerve fibers of the white matter are the most sensitive to a shortfall of blood. Part of the slowing of white matter in cognitive aging may come from this. The chain is still an inference and has not been shown directly.

contrast · 2

Dietary Patterns Compared
The MIND diet was designed specifically to protect cognition. In a cohort study, people who stuck to it closely had cognitive decline slower by the equivalent of 7.5 years of age (Morris 2015), but that is an observed association; in the only randomised controlled trial (Barnes 2023, 604 people, 3 years), cognition improved in both groups with no difference between them, and the control group also ate a healthy diet with mild calorie restriction. So saying MIND has been proven to prevent dementia goes too far.
Asian Ginseng
Sharpening the mind and memory is ginseng's second-biggest selling point, and a Cochrane systematic review concluded there is no convincing evidence that it improves cognition in healthy people. Not because the trials all came out negative, but because no credible effect can be pooled from them: they used different outcome measures, durations and doses, and every usable trial was in healthy people.

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How normal aging differs from dementia

EVIDENCEREVIEW 1

READ THE ORIGINAL

Growing old is not the same as developing dementia. The saying "the brain just goes with age" lumps three different things together: normal aging; mild cognitive impairment (MCI), an in-between state in which a person is clearly worse than their peers but still runs daily life on their own; and dementia.

Normal cognitive aging is selective, not a collapse of the whole system (Harada 2013, a review). The earliest and most common change is reacting half a beat later: finding words, doing sums and making decisions all take a little longer. This is a decline in processing speed. Holding a string of digits in mind, juggling several tasks, or solving an unfamiliar problem on the spot drifts down slowly after midlife. Vocabulary, general knowledge, and the judgment built up from years of reading people and situations often hold steady until about 70, and some keep growing. So a 70-year-old who cannot retrieve a name is common, yet their judgment about people and events may be better than it was at 30. Slow is not broken.

Dementia is not the inevitable end point of aging; many people live to a great age without it. Treating a slightly worse memory as an early sign of dementia is the first fear you can set down.

One kind of change has nothing to do with aging: speech that suddenly slurs, sudden weakness in the arm and leg on one side, or a drooping mouth should be treated as a stroke. Go to the emergency department immediately.

Educational content, not medical advice — consult a clinician.

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Cognitive Aging & Cognitive Reserve

Story

Connected to · 5

regulates · 3

Immune Aging & Inflammaging
The chronic low-grade inflammation of an aging immune system is linked with cognitive decline and is thought to be one of its drivers. It is not the only cause, and it is intertwined with vascular and metabolic factors.
Bacopa monnieri
Bacopa is thought to work by slowly changing the structure of neurons (in animal studies, hippocampal neurons grew more dendritic branches), which is why it takes about 12 weeks of daily use before any signal appears, and a single dose tested two hours later shows nothing. The positive results land on only two things, how fast you learn a list of new words and how fast you process information, and the effects are small; short-term attention and working memory show no difference on repeated testing.
Neurovascular coupling
When activity rises in part of the brain, neurons, glial cells and blood vessels work together to send more blood there; this is called neurovascular coupling. Some researchers propose that with age the small arteries respond to these signals more slowly, so local blood flow lags, and the long, thin nerve fibers of the white matter are the most sensitive to a shortfall of blood. Part of the slowing of white matter in cognitive aging may come from this. The chain is still an inference and has not been shown directly.

contrast · 2

Dietary Patterns Compared
The MIND diet was designed specifically to protect cognition. In a cohort study, people who stuck to it closely had cognitive decline slower by the equivalent of 7.5 years of age (Morris 2015), but that is an observed association; in the only randomised controlled trial (Barnes 2023, 604 people, 3 years), cognition improved in both groups with no difference between them, and the control group also ate a healthy diet with mild calorie restriction. So saying MIND has been proven to prevent dementia goes too far.
Asian Ginseng
Sharpening the mind and memory is ginseng's second-biggest selling point, and a Cochrane systematic review concluded there is no convincing evidence that it improves cognition in healthy people. Not because the trials all came out negative, but because no credible effect can be pooled from them: they used different outcome measures, durations and doses, and every usable trial was in healthy people.

Read full story

Stop 1/6

How normal aging differs from dementia

EVIDENCEREVIEW 1

READ THE ORIGINAL

Growing old is not the same as developing dementia. The saying "the brain just goes with age" lumps three different things together: normal aging; mild cognitive impairment (MCI), an in-between state in which a person is clearly worse than their peers but still runs daily life on their own; and dementia.

Normal cognitive aging is selective, not a collapse of the whole system (Harada 2013, a review). The earliest and most common change is reacting half a beat later: finding words, doing sums and making decisions all take a little longer. This is a decline in processing speed. Holding a string of digits in mind, juggling several tasks, or solving an unfamiliar problem on the spot drifts down slowly after midlife. Vocabulary, general knowledge, and the judgment built up from years of reading people and situations often hold steady until about 70, and some keep growing. So a 70-year-old who cannot retrieve a name is common, yet their judgment about people and events may be better than it was at 30. Slow is not broken.

Dementia is not the inevitable end point of aging; many people live to a great age without it. Treating a slightly worse memory as an early sign of dementia is the first fear you can set down.

One kind of change has nothing to do with aging: speech that suddenly slurs, sudden weakness in the arm and leg on one side, or a drooping mouth should be treated as a stroke. Go to the emergency department immediately.

Educational content, not medical advice — consult a clinician.