Bisher AKIL, MD

Archive for November 6th, 2019|Daily archive page

Physical Activity and Dementia

In Brain on November 6, 2019 at 3:35 pm

Growing evidence demonstrates that lifestyle behaviors modify dementia risk. Investigators from the Harvard Aging Brain Study assessed the effects of physical activity on β-amyloid ( peptide  crucially involved in Alzheimer’s disease as the main component of the amyloid plaques found in the brains of people with Alzheimer’s disease) burden, longitudinal cognitive decline, and neurodegeneration ( the progressive loss of structure or function of neurons, including death of neurons) in cognitively normal older adults.

Baseline physical activity was the daily number of steps counted over 5 to 7 days by a waistband pedometer (~5500 daily steps in these participants); β-amyloid burden was determined via Pittsburgh Compound B positron emission tomography (Positron emission tomography (PET) is a type of nuclear medicine procedure that measures metabolic activity of the cells of body tissues) , and vascular risk was calculated with the Framingham Heart Study cardiovascular disease risk score (estimates risk of heart attack in 10 years) .  Longitudinal neurodegeneration was measured by loss of gray matter ( part of the brain that contains most of the brain’s neuronal cell bodies) and cortical thickness (Cortex is the outer layer of the brain) seen on brain MRI, and a cognitive composite score indicated cognitive change over time.

Cross-sectional analysis of the 182 participants (57% female; mean age, 73), showed that greater physical activity was associated with lower vascular risk but not with β-amyloid burden. After a follow-up of 5 to 6 years, higher physical activity was associated with slower β-amyloid–related cognitive decline and gray-matter volume loss in multivariable analyses. Lower vascular risk was independently associated with slower β-amyloid–related cognitive decline and volume loss. Exploratory whole-brain analyses associated greater physical activity with slower β-amyloid–related cortical thinning in the entorhinal, insular, lateral temporal, and medial parietal regions but not the hippocampus.

Citation: Rabin JS et al. Associations of physical activity and β-amyloid with longitudinal cognition and neurodegeneration in clinically normal older adults. JAMA Neurol 2019 Jul 16; [e-pub]. (https://doi.org/10.1001/jamaneurol.2019.1879)

Appeared in NEJM Journal watch

Comments: many studies indicated that physical activity could help with dementia; this is a longitudinal study with biomarkers demonstrating the benefits- impressive-BA


Eat Meat – really?

In General Health on November 6, 2019 at 12:07 am

Current dietary guidelines implicate unprocessed red meat and processed meat in conferring adverse cardiovascular (CV) and cancer outcomes. However, these guidelines all have one or more limitations (conflict of interest for the authors; observational studies and not clinical trials [RCT]; other factors affecting outcome)

In this new guideline, an independent panel (Sponsoring Organization: Nutritional Recommendations (NutriRECS) international consortium) addresses each of these limitations, using findings from five comprehensive meta-analyses:  One meta-analysis included all randomized, controlled trial (RCT) evidence, three others included data from all observational studies with >1000 participants, and one concerned participants’ values and preferences about meat consumption. The panel’s evaluation produced the following summary results:

  1. Meta-analysis of the 12 RCTs showed no significant difference between patients who consumed higher versus lower quantities of red meat during longer than 10 years of follow-up for the outcomes of all-cause mortality, CV-related mortality, CV disease, or cancer-related mortality, including colorectal cancer.
  2. The observational studies showed that, for every 100 people who reduced processed or unprocessed meat intake by 3 servings per week, roughly 1 person avoided death and 1 person avoided a diagnosis of diabetes during 11 years of follow-up.

A panel suggests that adults may continue to consume unprocessed red meat and processed meat without incurring excess health risks.

Citation(s):

Johnston BC et al. Unprocessed red meat and processed meat consumption: Dietary guideline recommendations from the Nutritional Recommendations (NutriRECS) Consortium. Ann Intern Med 2019 Oct 1; [e-pub]. (https://doi.org/10.7326/M19-1621)

Appeared in NEJM Journal Watch: October 24,2019

Comments: These recommendations are actually weak and panel stated they are based on “low-certainty evidence”. Until there is better RCTs with less inherent biases(s), take these meats with a grain of salt-BA