Brain Health in Aging Adults

August 4, 2019

Three studies highlight sedentary behavior and memory, cognitive decline in psychosis, and risk of dementia with anticholinergic drugs.

Three studies highlight the issues of sedentary behavior and memory, the decline of brain health with age in psychosis, and risk of dementia with anticholinergic drugs: sitting too much is linked to changes in a section of the brain that is critical for memory; brain health declines as age, body mass index (BMI), and substance use increase in psychosis; and certain anticholinergic drugs appear to increase dementia risk.

Study 1. Sedentary behavior is associated with reduced brain thickness in middle-aged and older adults.

A group of 35 non-demented middle-aged and older adults were assessed using the International Physical Activity Questionnaire for older adults, which quantifies physical activity levels and asks about the average number of hours spent sitting per day. All participants had high resolution MRI scans to provide a detailed investigation of the medial temporal lobe, a brain region involved in the formation of new memories.

Controlling for age, total medial temporal lobe thickness correlated inversely with hours of sitting per day. The results suggest that sedentary behavior is a significant predictor of thinning of the medial temporal lobe and that physical activity, even at high levels, is insufficient to offset the harmful effects of sitting for extended periods.

Clinical Implications: Medial temporal lobe thinning can be a precursor to cognitive decline and dementia in middle-aged and older adults. Reducing sedentary behavior may be a possible target for interventions designed to improve brain health in people at risk for Alzheimer disease, said the researchers, led by Prabha Siddarth of the Semel Institute for Neuroscience and Human Behavior, UCLA, Los Angeles, CA.

Source: Siddarth P, et al. Sedentary behavior associated with reduced medial temporal lobe thickness in middle-aged and older adults.PLoS One. 2018;13:e0195549.

Study 2. Older age, higher BMI, and substance use have been linked to specific patterns of brain structure and function in patients with psychosis.

A group of 140 patients diagnosed with psychosis underwent high-resolution MRI brain scans to measure brain volume, cortical thickness, connections between brain regions, and connectivity of brain regions during mental tasks. A statistical method called sparse canonical correlation revealed relationships between features of brain integrity and measures of age, cognitive ability, BMI, substance use, physical activity, psychological trauma, family history of mental problems, and symptom severity.

The results show that older age, higher BMI, and more severe psychotic symptoms were negatively associated with cortical thickness and brain activation during mental tasks. Conversely, higher IQ showed positive associations. In addition, substance use was negatively associated with measures of brain volume and brain wiring.

Clinical Implications: “These new results provide new insights on the many factors that influence brain integrity in patients with psychosis and provide evidence for the need for integrated physical and cognitive interventions in addition to psychiatric care. Patients with psychosis often have multiple health problems that impair their daily function and reduce life expectancy compared to the general population. Improving physical well-being and brain health should be the two pillars of clinical care for patients with psychosis,” said lead author Sophia Frangou, MD, PhD, Professor of Psychiatry, Icahn School of Medicine at Mount Sinai in New York.

Source: Moser DA, et al. Multivariate Associations Among Behavioral, Clinical, and Multimodal Imaging Phenotypes in Patients With Psychosis. JAMA Psychiatry. 2018;75:386-395.

Study 3. A robust association exists between some classes of anticholinergic drugs and future dementia incidence.

A case-control study included 40,770 patients aged 65 to 99 years with a diagnosis of dementia and 283,933 controls without dementia. Odds ratios were calculated for incident dementia, adjusted for a range of demographic and health-related covariates. About one-third in each group was prescribed at least one anticholinergic drug with an Anticholinergic Cognitive Burden (ACB) score of 3 (definite anticholinergic activity). The adjusted odds ratio for any anticholinergic drug with an ACB score of 3 was 1.11.

Dementia was associated with an increasing average ACB score. The risk of dementia increased with greater exposure for antidepressant, urological, and anti-Parkinson drugs with an ACB score of 3.

Clinical Implications: The results suggest that anticholinergics in general should be avoided in older adults. “Clinicians should continue to be vigilant with respect to the use of anticholinergic drugs, and should consider the risk of long-term cognitive effects, as well as short term effects, associated with specific drug classes when performing their risk-benefit analysis,” said the researchers, led by Kathryn Richardson of University of East Anglia, Norwich, UK.

Source: Richardson K, Fox C, Maidment I, et al. Anticholinergic drugs and risk of dementia: case-control study. BMJ. 2018;361:k1315.

Editor's note: This slideshow was published on May 11, 2018, and has since been updated.