Brain inflammation produces a variety of emotional, behavior and cognitive symptoms.

I remember clearly a patient I cared for with central nervous system lupus erythrematosis (SLE). With SLE flairs she developed flagrant psychotic symptoms including hallucinations requiring inpatient psychiatric care.

Between flares she had no significant psychiatric symptoms.

Nicole Castanon and two colleagues from France have published a review of the role of obesity-associated inflammation and brain dysfunction.

Obesity is linked to a variety of blood markers of inflammation including proinflammatory cytokines, IL-6, interleuking and TNF. These inflammatory markers diminish with weight loss accomplished by either diet restriction or bariatric surgery.

The authors note evidence obesity is associated with the following:

• Depression (not all studies and not confirmed in animal models)
• Anxiety
• Memory and other cognitive impairment
• Increased age-related cognitive decline

So how could primarily a peripheral body condition impact the brain?

Figure from Castonon et al

The authors summarize potential mechanisms in a nice figure that I have reproduced here as it is open-access under the Creative Common Attribution License. See the citation below for the source of this figure.

Increased adipose (fat) tissue is known to promote local inflammation including recruitment of microphages and secretion of inflammatory chemicals. 

This peripheral adipose inflammation can transfer to the brain through the vagus nerve, hormones or other blood inflammtory chemicals and cellular pathways.

Brain evidence for this transfer has been noted via inflammation in the hippocampus, basal ganglia and prefrontal cortex.

Additional obesity-related brain inflammatory effect has been noted through dysruption of the hypothalamic/pituitary/adrenal (HPA) axis and changes in brain serotonin and dopamine metabolism.

A second potential pathway is described as working through changes in the gut in obesity. Obesity is linked to changes in gut bacteria composition, a change that results in increased gut permeability. This permeability change potentially promotes increased gut-blood absorption of endotoxins that can promote a systemic anti-inflammatory response. 

The authors note their review of this topic supports weight management approaches to limit the effect of obesity on the brain. Additionally, there may be some evidence to investigate anti-inflammatory diet and drug interventions for those with combined obesity and brain disorders. 

Readers with more interest in this topic can access the free full-text manuscript by clicking on the link below.

Photo of blue jay in the snow is from the author's files.

Figure of obesity-brain interaction is from Castanon, Lasselin and Capuron, citation below.

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Castanon N, Lasselin J, & Capuron L (2014). Neuropsychiatric comorbidity in obesity: role of inflammatory processes. Frontiers in endocrinology, 5 PMID: 24860551

Dietary intake of whole grains and fiber shows consistent beneficial effects on a variety of health and mortality measures.

In a post in 2011, I reviewed study results from the NIH-AARP cohort. That study reported reduced cardiovascular disease but not cancer in men and women with the highest fiber intake.

A recent Harvard University study examined mortality risk in a group of U.S. health professionals grouped by level of whole grain intake.

Participants in this study were over 118,000 men and women from the Health Professionals Follow-Up Study and the Nurses' Health Study.

Participants completed dietary questionnaires every two to four years over the course of the study. Each participant had an estimated daily grain consumption level calculated from dry weight whole grain intake of rice, bread, pasta and breakfast cereals.

Participants were grouped into quintiles (5 groups each containing 20% of the sample) from lowest to highest whole grain intake. Mean levels of whole grain daily intake in three of the five quintiles for women/women were reported:

• Lowest (g/day): 4.2/5.9
• Low: 9.7/14.4
• Middle: 14.7/22.1
• High: 21.1/31.3
• Highest: 33.0/47.8

The study team follow participants for death using next of kin, postal information and the National Death Index.

Death certificate and medical record information was used to assign deaths into cardiovascular deaths (including myocardial infarction and stroke), cancer or other categories.

During the follow-up period of 26 years, 15,106 deaths were identified with 2989 assigned to the cardiovascular disease death group, 5964 assigned to cancer and 6,153 assigned to other causes.

Analysis of the rates of heart/stroke death rates by whole grain intake showed a consistent finding in men and women.

Those in the highest whole grain intake group had about a 15% reduction in rates of heart/stroke deaths during the follow-up period (see chart left).

Additionally, total mortality was about 8% over the follow-up period in the highest whole grain intake group.

This estimate controlled for potential confounding variables such as age, BMI, smoking status, physical activity and aspirin use.

Getting to the high or higher quintile group status takes between two and three daily servings of whole wheat, whole oats, whole cornmeal, whole rye, brown rice, popcorn or bran additive.

One concern with whole grains is the carbohydrate levels. Individuals on a low carbohydrate diet may find a big portion of their daily carbohydrate limit is taken up with two or three portions of whole grain. Using bran additives, like All-Bran Buds may reduce the carbohydrate load associated with whole grains.

The authors note their findings are consistent with several other studies linking whole grain intake to lower heart/stroke death risk. Additionally they note their findings support federal guidelines urging daily whole grain intake.

This is an important study due to the large sample size, ability to examine effects in both men and women and the quality of dietary and mortality data.

Photo of blue jay is from the author's files.

Chart was an original chart made by author using data from the manuscript.

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Wu H, Flint AJ, Qi Q, van Dam RM, Sampson LA, Rimm EB, Holmes MD, Willett WC, Hu FB, & Sun Q (2015). Association Between Dietary Whole Grain Intake and Risk of Mortality: Two Large Prospective Studies in US Men and Women. JAMA internal medicine PMID: 25559238