Bisher AKIL, MD

Archive for the ‘Brain’ Category

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]. (

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

Neurosyphilis is probably underestimated in HIV

In Brain on March 2, 2009 at 10:07 pm

Asymptomatic neurosyphilis in HIV infected patients is probably grossly underestimated. he most recent CDC guidelines recommend spinal fluid analysis for HIV-infected patients who have late latent syphilis, syphilis of unknown duration, or serologic failure after a course of syphilis treatment. Other authorities suggest that spinal fluid should be obtained in individuals with CD4 counts ≤350 cells/mm3 or rapid plasma reagin (RPR) titers ≥1:32. To determine which nomogram might yield an ANS diagnosis most efficiently, investigators reviewed data from a large cohort of HIV-infected patients at the Johns Hopkins Moore Clinic. In a recent study, the authors discovered that 202 of 231 patients (87%) did not have neurological symptoms. Immediate lumbar puncture was performed on 46 patients and 22% had neurosyphilis without any symptoms! (Journal of Clinical Infectious Diseases, 2009 Mar 15;48(6):816-21) – Comments: Neurosyphilis remains under diagnosed and under treated. Just because there are no symptoms, does not mean there is no disease. Lumbar puncture is a lot easier that neurosyphilis. BA