Health

A review of 56 randomized clinical trials found that psychotherapy may be effective in reducing inflammation. The trials included several different types of interventions, including cognitive behavior therapy (CBT), CBT plus medication, grief and bereavement support, a combination of two or more psychotherapies, and psychoeducation, among others. CBT was the best at boosting the immune system, followed by multiple or combined interventions. The benefits of CBT on the immune system lasted for at least six months following treatment.

https://www.eurekalert.org/pub_releases/2020-06/uoc--cbt060220.php

Shields GS, Spahr CM, Slavich GM. Psychosocial Interventions and Immune System Function: A Systematic Review and Meta-analysis of Randomized Clinical Trials. JAMA Psychiatry. Published online June 03, 2020. doi:10.1001/jamapsychiatry.2020.0431 https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2766707

A study folowing nearly 500 patients with existing cardiovascular disease for more than two decades has found that insulin resistance is linked to faster cognitive decline in both diabetic and non-diabetic patients.

Executive function and memory were particularly affected.

Insulin resistance is a condition in which cells fail to respond normally to the hormone insulin, and so require higher levels of insulin to get the amount of glucose they need. But without sufficient insulin, excess glucose builds up in the bloodstream, leading to prediabetes, diabetes, and other serious health disorders.

Exercising, maintaining a balanced and healthy diet, and watching your weight, will help you prevent insulin resistance.

https://www.eurekalert.org/pub_releases/2017-03/ip-irm032317.php

Lutski M, Weinstein G, Goldbourt U, Tanne D. Insulin Resistance and Future Cognitive Performance and Cognitive Decline in Elderly Patients with Cardiovascular Disease. J Alzheimers Dis. 2017 Mar 10. doi: 10.3233/JAD-161016

Data from 473 adults aged 20-87 has found striking differences in the volume of white matter among middle-aged and older adults, depending on the weight of the individuals. These changes were also associated with greater brain shrinkage. These differences were equivalent to some 10 years in brain age – e.g., an overweight person at, say, 50 years old had a comparable white matter volume to a lean person aged 60 years.

The differences were not found among younger adults. Nor was there any connection between being overweight or obese and an individual’s cognitive abilities, as measured using a standard test similar to an IQ test.

http://www.eurekalert.org/pub_releases/2016-08/uoc-boo080316.php

Ronan, L et al. Obesity associated with increased brain-age from mid-life. Neurobiology of Aging; e-pub 27 July 2016; DOI: 10.1016/j.neurobiolaging.2016.07.010

The connection between higher BMI and greater cognitive decline with age is being blamed on inflammation.

Data from the English Longitudinal Study of Aging, involving some 21,500 older adults (50+) showed that, the higher the BMI at the start, the greater the rise in lovels of C-reactive protein over the next four years. CRP is a marker in the blood of systemic inflammation. This 4-year change in CRP predicted change in cognition six years after the start of the study.

https://www.eurekalert.org/pub_releases/2016-10/uoa-hyb101716.php

Bourassa, K., & Sbarra, D. A. (2017). Body mass and cognitive decline are indirectly associated via inflammation among aging adults. Brain, Behavior, and Immunity, 60, 63–70. https://doi.org/10.1016/j.bbi.2016.09.023

Data from the Advanced Cognitive Training for Independent and Vital Elderly, involving 701 older adults (mean age 73.6) with normal weight, 1,081 overweight, and 902 who were obese, found that memory training provided only one-third the benefit to older adults with obesity compared with the benefit it provided to normal-weight older adults.

Participants were followed for 10 years. Over that time, the effects of training in reasoning and speed of processing didn’t differe between the weight groups. However, the effect of memory training on obese participants was just 38% of that observed in participants with normal-weight BMI.

Memory training focused on improving verbal episodic memory through instruction and practice in strategy use. Reasoning training focused on improving the ability to solve problems that contained a serial pattern. Speed training focused on visual search and the ability to process increasingly more information presented in successively shorter inspection times.

Of the participants, three-quarters were women; three-quarters were white and one-quarter were African-American.

https://www.eurekalert.org/pub_releases/2017-01/iu-oaw011017.php

Clark, D. O., Xu, H., Callahan, C. M., & Unverzagt, F. W. (2016). Does Body Mass Index Modify Memory, Reasoning, and Speed of Processing Training Effects in Older Adults. Obesity, 24(11), 2319–2326. https://doi.org/10.1002/oby.21631

Data from the GENOA study, which began in 1997 and involved African Americans with high blood pressure and their siblings, has found that obesity as such was not linked to cognitive decline. The key factor was abdominal fat rather than BMI.

Having too much belly fat in mid- and late-life was linked to a much higher risk of cognitive decline. Among middle-aged adults, losing weight was linked to higher cognitive scores, while gaining weight was linked to lower scores. However, in later life, losing weight was linked to lower scores (I note that losing weight in old age is often a marker of developing dementia), and gaining weight was linked to better scores.

People in the study ranged in age from 35- to 86-years-old; 78% were women and most were obese. Participants were assessed in 1997-99, 2001-6, and 2009-11.

https://www.eurekalert.org/pub_releases/2017-05/ags-teo050817.php

West, N. A., Lirette, S. T., Cannon, V. A., Turner, S. T., Mosley, T. H., & Windham, B. G. (2017). Adiposity, Change in Adiposity, and Cognitive Decline in Mid- and Late Life. Journal of the American Geriatrics Society, 65(6), 1282–1288. https://doi.org/10.1111/jgs.14786

A small study involving 30 older adults (60+) with amnestic MCI, has found that those who underwent a year of aerobic exercise training showed a 47% improvement in some memory scores, compared with minimal change in those who participated in a stretching program. Moreover, brain scans showed the exercise group increased blood flow into two critical brain regions: the anterior cingulate cortex and the hippocampus.

https://www.eurekalert.org/pub_releases/2020-05/usmc-eim051820.php

Thomas, Binu P. et al. 2020. Brain Perfusion Change in Patients with Mild Cognitive Impairment After 12 Months of Aerobic Exercise Training. Journal of Alzheimer’s Disease, 1 Jan. 2020: 617–631.

In one of the largest studies linking obesity with brain dysfunction, brain scans from more than 17,000 individuals (aged 18-94; mean age 40.8) were analyzed to measure blood flow and brain activity. Across all ages, higher BMI was associated with decreased cerebral blood flow. This was seen in almost all brain regions, and particularly so in regions known to be vulnerable to Alzheimer’s: temporal and parietal lobes, hippocampus, posterior cingulate gyrus, and precuneus.

https://www.eurekalert.org/pub_releases/2020-08/ip-bwh080520.php

Amen, Daniel G. et al. 2020. Patterns of Regional Cerebral Blood Flow as a Function of Obesity in Adults. Journal of Alzheimer’s Disease, 1 Jan. 2020: 1–7.

Data from 1,588 dementia-free older adults (average age 79.5) from the very long-running Rush Memory and Aging Project found that a higher cardiovascular risk burden was associated with faster decline in episodic memory, working memory and perceptual speed. It didn’t significantly affect semantic memory or visuospatial ability.

Cardiovascular risk was assessed using the Framingham General Cardiovascular Risk Scores (FGCRS).

Brain scans for some of these participants also found that higher FGCRS was associated with smaller volumes of hippocampus, cortical gray matter and total brain, and a greater volume of white matter hyperintensities. Decreases in hippocampal and gray matter are typical markers of Alzheimer’s.

Episodic memory and working memory were related to hippocampal volume, but perceptual speed was associated with white matter hyperintensities.

https://www.eurekalert.org/pub_releases/2020-05/acoc-mhh051420.php

Song, R., Xu, H., Dintica, C. S., Pan, K.-Y., Qi, X., Buchman, A. S., Bennett, D. A., & Xu, W. (2020). Associations Between Cardiovascular Risk, Structural Brain Changes, and Cognitive Decline. Journal of the American College of Cardiology, 75(20), 2525–2534. https://doi.org/10.1016/j.jacc.2020.03.053

A mouse study explains why excessive weight around our middle affects cognition. It seems that such fat, known as visceral adiposity, generates high, chronic levels of a signal that encourages the formation of inflammasome complexes that amplify the immune response and inflammation.

A protein called NLRP3 is a core component of the inflammasome complex in the fat, and it’s what promotes the production and release of interleukin-1 beta by fat cells. When NLRP3 was blocked in mice, they became protected against such inflammation and cognitive problems. When visceral adipose tissue from obese mice and obese mice missing NLRP3 was transplanted into lean mice, the tissue from those missing NLRP3 had no deleterious effect, but the tissue from the intact obese mice caused increased levels of interleukin-1 beta in the hippocampus, and impaired cognition.

Mice missing interleukin-1 beta’s receptor on the microglia were also protected.

There are indications that interleukin-1 beta also prompts microglia to wrap around synapses, potentially interfering with the communication between neurons.

https://www.eurekalert.org/pub_releases/2020-03/mcog-vfd030220.php

Guo, D.-H., Yamamoto, M., Hernandez, C. M., Khodadadi, H., Baban, B., & Stranahan, A. M. (2020). Visceral adipose NLRP3 impairs cognition in obesity via IL-1R1 on CX3CR1⁺ cells. The Journal of Clinical Investigation, 130(4), 1961–1976. https://doi.org/10.1172/JCI126078