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, new research suggests.
The study provides important “pieces of the puzzle” of the diet and cognition connection, but the results aren’t “ready for prime time,” study investigator Roger S. McIntyre, MD, professor of psychiatry and pharmacology, University of Toronto, said in an interview.
“I don’t think we’re there yet when it comes to recommending supplementation to the general public,” said Dr. McIntyre, adding a larger “more compelling study” is needed.
The study was published online Jan. 14 in The American Journal of Geriatric Psychiatry.
Clinically meaningful?
Research shows that 25%-50% of community-dwelling adults aged 65-85 years have some cognitive impairment. Other evidence indicates cognition is affected by dietary fat intake.
Many lines of research show that alterations in lipid homeostasis can cause brain dysfunction, said Dr. McIntyre. “This shouldn’t surprise us because our brain is made up of protein, water, and fat.”
This new analysis used combined data from the 2011-2012 and 2013-2014 cycles of the National Health and Nutrition Examination Survey (NHANES), a series of ongoing cross-sectional surveys conducted by the Centers for Disease Control and Prevention. The data are collected in two phases, an in-home face-to-face interview and a physical examination.
Researchers obtained dietary intake information through two 24-hour dietary recall interviews. Dietary information included total energy (kcal/d), intakes in grams per day (g/d) of total fat, saturated fatty acid (SFAT), monounsaturated fatty acid (MUFA), PUFA, total omega-3 and total omega-6 fatty acids, and milligrams per day (mg/d) of cholesterol.
For cognitive function, the researchers used total and delayed recall scores of the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD), the animal fluency test, and the digit symbol substitution test (DSST).
The study included 2,253 adults aged 60 years and older (mean age, 69.4 years) and 51% were non-Hispanic White individuals.
After adjustment for age, sex, race/ethnicity, educational attainment, smoking status, alcohol consumption, income, and total energy, dietary intake of PUFA and omega-6 fatty acid was positively associated with DSST.
The DSST score increased about 0.06 standard deviation (SD) (about 1 score) with each SD increase in these fatty acids (8.8 g/d for PUFA and 7.9 g/d for omega-6) (P values were .02 for PUFA and .01 for omega-6).
However, it’s unclear what an improvement of 1 DSST score means clinically, said Dr. McIntyre. “The P value is significant, but how does that translate? Does this mean a person can now think more clearly or function better?”
‘Million dollar question’ remains unanswered
The fact that omega-6, considered neuroinflammatory, was associated with improved DSST score illustrates the complexity of this field, said Dr. McIntyre.
“We’re learning that when it comes to inflammation, many of the molecules in our brain that are implicated as anti-inflammatory can also be pro-inflammatory, so bad guys can be good guys and good guys can be bad guys.”
It speaks to the notion of homeostasis, he added. “Just like a seesaw; when you push this part down, that part goes up.”
The analysis showed the animal fluency score increased about 0.05 SD (around 0.3 score) with each SD (1.1 g/d) increase in dietary intake of omega-3.
There were no significant associations between other dietary fat intake and cognitive performance.
The researchers investigated the role of oxidative stress and antioxidant biomarkers (gamma glutamyl transpeptidase [GGT], bilirubin, uric acid, and vitamin D).
Cells produce oxidative radicals that are normally “mopped up” by our “innate antioxidant capability,” said Dr. McIntyre. “But in states of cognitive impairment, these oxidative stress markers accumulate and they exceed what the normal innate response is able to manage.”
The study showed GGT levels decreased with increased PUFA and omega-6 fatty acid intakes; levels of bilirubin decreased with increase in most dietary fat intakes; uric acid levels decreased with MUFA intake and omega-6/omega-3 ratio; and vitamin D levels increased with omega-3 fatty acid intake but decreased with SFAT intake.
Causal mediation analysis showed the association between dietary intake of fatty acids and DSST performance was partially mediated by GGT levels. However, Dr. McIntyre emphasized that this does not prove causality.
“The million dollar question is, is this the sole explanation for the association? In other words, is it the oxidative stress that caused the cognitive impairment and therefore correcting it improved it, or is it the case that oxidative stress is a proxy of other activities that are also taking place?”
A ‘plausible’ link
In an editorial, Candida Rebello, PhD, of the department of integrated physiology and molecular medicine at Pennington Biomedical Research Center, Baton Rouge, La., said the finding that omega-3 and omega-6 fatty acids are positively associated with cognition in older adults makes some sense.
She noted that aging is associated with an overt inflammatory phenotype, and evidence shows these fatty acids are precursors for bioactive molecules that play a role in self-limiting the acute inflammatory response.
Dr. Rebello said the positive association of omega-6 fatty acid with cognition shown in this study contrasts with the “common belief” that increasing dietary intake of these fatty acids enhances inflammation, but agreed the association is “plausible.”
She said it’s “essential” to determine “the underlying mechanisms that regulate the diverse features of inflammation and sort out the processes that protect from neuronal damage and those that contribute towards it.”
She noted the ratio of omega-6 to omega-3 is about 15:1 in the present day Western diet, as opposed to a 1:1 ratio in diets of the past. Omega-3 fatty acids are found in fish oil supplements and fatty fish like mackerel and salmon, while cereal, grains, and vegetable oil are sources of omega-6.
Attaining a measure of balance of fatty acids in the diet may be a “prudent approach,” said Dr. Rebello. “Substituting some meat entrées with fatty fish and polyunsaturated vegetable oils with monounsaturated fats such as olive oil are small changes that are likely to garner adherence.”
Dr. Rebello noted that the study used NHANES food intake data, which rely on participant self-report and so may not be accurate.
The study received funding from the MOE (Ministry of Education in China) Project of Humanities and Social Sciences and the Research Startup Fund of Southwest University. Dr. McIntyre has received research grant support from CIHR/GACD/Chinese National Natural Research Foundation and speaker/consultation fees from Lundbeck, Janssen, Purdue, Pfizer, Otsuka, Takeda, Neurocrine, Sunovion, Bausch Health, Novo Nordisk, Kris, Sanofi, Eisai, Intra-Cellular, NewBridge Pharmaceuticals, and AbbVie. He is a CEO of Braxia Scientific Corp.
A version of this article first appeared on Medscape.com.
, new research suggests.
The study provides important “pieces of the puzzle” of the diet and cognition connection, but the results aren’t “ready for prime time,” study investigator Roger S. McIntyre, MD, professor of psychiatry and pharmacology, University of Toronto, said in an interview.
“I don’t think we’re there yet when it comes to recommending supplementation to the general public,” said Dr. McIntyre, adding a larger “more compelling study” is needed.
The study was published online Jan. 14 in The American Journal of Geriatric Psychiatry.
Clinically meaningful?
Research shows that 25%-50% of community-dwelling adults aged 65-85 years have some cognitive impairment. Other evidence indicates cognition is affected by dietary fat intake.
Many lines of research show that alterations in lipid homeostasis can cause brain dysfunction, said Dr. McIntyre. “This shouldn’t surprise us because our brain is made up of protein, water, and fat.”
This new analysis used combined data from the 2011-2012 and 2013-2014 cycles of the National Health and Nutrition Examination Survey (NHANES), a series of ongoing cross-sectional surveys conducted by the Centers for Disease Control and Prevention. The data are collected in two phases, an in-home face-to-face interview and a physical examination.
Researchers obtained dietary intake information through two 24-hour dietary recall interviews. Dietary information included total energy (kcal/d), intakes in grams per day (g/d) of total fat, saturated fatty acid (SFAT), monounsaturated fatty acid (MUFA), PUFA, total omega-3 and total omega-6 fatty acids, and milligrams per day (mg/d) of cholesterol.
For cognitive function, the researchers used total and delayed recall scores of the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD), the animal fluency test, and the digit symbol substitution test (DSST).
The study included 2,253 adults aged 60 years and older (mean age, 69.4 years) and 51% were non-Hispanic White individuals.
After adjustment for age, sex, race/ethnicity, educational attainment, smoking status, alcohol consumption, income, and total energy, dietary intake of PUFA and omega-6 fatty acid was positively associated with DSST.
The DSST score increased about 0.06 standard deviation (SD) (about 1 score) with each SD increase in these fatty acids (8.8 g/d for PUFA and 7.9 g/d for omega-6) (P values were .02 for PUFA and .01 for omega-6).
However, it’s unclear what an improvement of 1 DSST score means clinically, said Dr. McIntyre. “The P value is significant, but how does that translate? Does this mean a person can now think more clearly or function better?”
‘Million dollar question’ remains unanswered
The fact that omega-6, considered neuroinflammatory, was associated with improved DSST score illustrates the complexity of this field, said Dr. McIntyre.
“We’re learning that when it comes to inflammation, many of the molecules in our brain that are implicated as anti-inflammatory can also be pro-inflammatory, so bad guys can be good guys and good guys can be bad guys.”
It speaks to the notion of homeostasis, he added. “Just like a seesaw; when you push this part down, that part goes up.”
The analysis showed the animal fluency score increased about 0.05 SD (around 0.3 score) with each SD (1.1 g/d) increase in dietary intake of omega-3.
There were no significant associations between other dietary fat intake and cognitive performance.
The researchers investigated the role of oxidative stress and antioxidant biomarkers (gamma glutamyl transpeptidase [GGT], bilirubin, uric acid, and vitamin D).
Cells produce oxidative radicals that are normally “mopped up” by our “innate antioxidant capability,” said Dr. McIntyre. “But in states of cognitive impairment, these oxidative stress markers accumulate and they exceed what the normal innate response is able to manage.”
The study showed GGT levels decreased with increased PUFA and omega-6 fatty acid intakes; levels of bilirubin decreased with increase in most dietary fat intakes; uric acid levels decreased with MUFA intake and omega-6/omega-3 ratio; and vitamin D levels increased with omega-3 fatty acid intake but decreased with SFAT intake.
Causal mediation analysis showed the association between dietary intake of fatty acids and DSST performance was partially mediated by GGT levels. However, Dr. McIntyre emphasized that this does not prove causality.
“The million dollar question is, is this the sole explanation for the association? In other words, is it the oxidative stress that caused the cognitive impairment and therefore correcting it improved it, or is it the case that oxidative stress is a proxy of other activities that are also taking place?”
A ‘plausible’ link
In an editorial, Candida Rebello, PhD, of the department of integrated physiology and molecular medicine at Pennington Biomedical Research Center, Baton Rouge, La., said the finding that omega-3 and omega-6 fatty acids are positively associated with cognition in older adults makes some sense.
She noted that aging is associated with an overt inflammatory phenotype, and evidence shows these fatty acids are precursors for bioactive molecules that play a role in self-limiting the acute inflammatory response.
Dr. Rebello said the positive association of omega-6 fatty acid with cognition shown in this study contrasts with the “common belief” that increasing dietary intake of these fatty acids enhances inflammation, but agreed the association is “plausible.”
She said it’s “essential” to determine “the underlying mechanisms that regulate the diverse features of inflammation and sort out the processes that protect from neuronal damage and those that contribute towards it.”
She noted the ratio of omega-6 to omega-3 is about 15:1 in the present day Western diet, as opposed to a 1:1 ratio in diets of the past. Omega-3 fatty acids are found in fish oil supplements and fatty fish like mackerel and salmon, while cereal, grains, and vegetable oil are sources of omega-6.
Attaining a measure of balance of fatty acids in the diet may be a “prudent approach,” said Dr. Rebello. “Substituting some meat entrées with fatty fish and polyunsaturated vegetable oils with monounsaturated fats such as olive oil are small changes that are likely to garner adherence.”
Dr. Rebello noted that the study used NHANES food intake data, which rely on participant self-report and so may not be accurate.
The study received funding from the MOE (Ministry of Education in China) Project of Humanities and Social Sciences and the Research Startup Fund of Southwest University. Dr. McIntyre has received research grant support from CIHR/GACD/Chinese National Natural Research Foundation and speaker/consultation fees from Lundbeck, Janssen, Purdue, Pfizer, Otsuka, Takeda, Neurocrine, Sunovion, Bausch Health, Novo Nordisk, Kris, Sanofi, Eisai, Intra-Cellular, NewBridge Pharmaceuticals, and AbbVie. He is a CEO of Braxia Scientific Corp.
A version of this article first appeared on Medscape.com.
, new research suggests.
The study provides important “pieces of the puzzle” of the diet and cognition connection, but the results aren’t “ready for prime time,” study investigator Roger S. McIntyre, MD, professor of psychiatry and pharmacology, University of Toronto, said in an interview.
“I don’t think we’re there yet when it comes to recommending supplementation to the general public,” said Dr. McIntyre, adding a larger “more compelling study” is needed.
The study was published online Jan. 14 in The American Journal of Geriatric Psychiatry.
Clinically meaningful?
Research shows that 25%-50% of community-dwelling adults aged 65-85 years have some cognitive impairment. Other evidence indicates cognition is affected by dietary fat intake.
Many lines of research show that alterations in lipid homeostasis can cause brain dysfunction, said Dr. McIntyre. “This shouldn’t surprise us because our brain is made up of protein, water, and fat.”
This new analysis used combined data from the 2011-2012 and 2013-2014 cycles of the National Health and Nutrition Examination Survey (NHANES), a series of ongoing cross-sectional surveys conducted by the Centers for Disease Control and Prevention. The data are collected in two phases, an in-home face-to-face interview and a physical examination.
Researchers obtained dietary intake information through two 24-hour dietary recall interviews. Dietary information included total energy (kcal/d), intakes in grams per day (g/d) of total fat, saturated fatty acid (SFAT), monounsaturated fatty acid (MUFA), PUFA, total omega-3 and total omega-6 fatty acids, and milligrams per day (mg/d) of cholesterol.
For cognitive function, the researchers used total and delayed recall scores of the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD), the animal fluency test, and the digit symbol substitution test (DSST).
The study included 2,253 adults aged 60 years and older (mean age, 69.4 years) and 51% were non-Hispanic White individuals.
After adjustment for age, sex, race/ethnicity, educational attainment, smoking status, alcohol consumption, income, and total energy, dietary intake of PUFA and omega-6 fatty acid was positively associated with DSST.
The DSST score increased about 0.06 standard deviation (SD) (about 1 score) with each SD increase in these fatty acids (8.8 g/d for PUFA and 7.9 g/d for omega-6) (P values were .02 for PUFA and .01 for omega-6).
However, it’s unclear what an improvement of 1 DSST score means clinically, said Dr. McIntyre. “The P value is significant, but how does that translate? Does this mean a person can now think more clearly or function better?”
‘Million dollar question’ remains unanswered
The fact that omega-6, considered neuroinflammatory, was associated with improved DSST score illustrates the complexity of this field, said Dr. McIntyre.
“We’re learning that when it comes to inflammation, many of the molecules in our brain that are implicated as anti-inflammatory can also be pro-inflammatory, so bad guys can be good guys and good guys can be bad guys.”
It speaks to the notion of homeostasis, he added. “Just like a seesaw; when you push this part down, that part goes up.”
The analysis showed the animal fluency score increased about 0.05 SD (around 0.3 score) with each SD (1.1 g/d) increase in dietary intake of omega-3.
There were no significant associations between other dietary fat intake and cognitive performance.
The researchers investigated the role of oxidative stress and antioxidant biomarkers (gamma glutamyl transpeptidase [GGT], bilirubin, uric acid, and vitamin D).
Cells produce oxidative radicals that are normally “mopped up” by our “innate antioxidant capability,” said Dr. McIntyre. “But in states of cognitive impairment, these oxidative stress markers accumulate and they exceed what the normal innate response is able to manage.”
The study showed GGT levels decreased with increased PUFA and omega-6 fatty acid intakes; levels of bilirubin decreased with increase in most dietary fat intakes; uric acid levels decreased with MUFA intake and omega-6/omega-3 ratio; and vitamin D levels increased with omega-3 fatty acid intake but decreased with SFAT intake.
Causal mediation analysis showed the association between dietary intake of fatty acids and DSST performance was partially mediated by GGT levels. However, Dr. McIntyre emphasized that this does not prove causality.
“The million dollar question is, is this the sole explanation for the association? In other words, is it the oxidative stress that caused the cognitive impairment and therefore correcting it improved it, or is it the case that oxidative stress is a proxy of other activities that are also taking place?”
A ‘plausible’ link
In an editorial, Candida Rebello, PhD, of the department of integrated physiology and molecular medicine at Pennington Biomedical Research Center, Baton Rouge, La., said the finding that omega-3 and omega-6 fatty acids are positively associated with cognition in older adults makes some sense.
She noted that aging is associated with an overt inflammatory phenotype, and evidence shows these fatty acids are precursors for bioactive molecules that play a role in self-limiting the acute inflammatory response.
Dr. Rebello said the positive association of omega-6 fatty acid with cognition shown in this study contrasts with the “common belief” that increasing dietary intake of these fatty acids enhances inflammation, but agreed the association is “plausible.”
She said it’s “essential” to determine “the underlying mechanisms that regulate the diverse features of inflammation and sort out the processes that protect from neuronal damage and those that contribute towards it.”
She noted the ratio of omega-6 to omega-3 is about 15:1 in the present day Western diet, as opposed to a 1:1 ratio in diets of the past. Omega-3 fatty acids are found in fish oil supplements and fatty fish like mackerel and salmon, while cereal, grains, and vegetable oil are sources of omega-6.
Attaining a measure of balance of fatty acids in the diet may be a “prudent approach,” said Dr. Rebello. “Substituting some meat entrées with fatty fish and polyunsaturated vegetable oils with monounsaturated fats such as olive oil are small changes that are likely to garner adherence.”
Dr. Rebello noted that the study used NHANES food intake data, which rely on participant self-report and so may not be accurate.
The study received funding from the MOE (Ministry of Education in China) Project of Humanities and Social Sciences and the Research Startup Fund of Southwest University. Dr. McIntyre has received research grant support from CIHR/GACD/Chinese National Natural Research Foundation and speaker/consultation fees from Lundbeck, Janssen, Purdue, Pfizer, Otsuka, Takeda, Neurocrine, Sunovion, Bausch Health, Novo Nordisk, Kris, Sanofi, Eisai, Intra-Cellular, NewBridge Pharmaceuticals, and AbbVie. He is a CEO of Braxia Scientific Corp.
A version of this article first appeared on Medscape.com.