Drops in Blood Pressure, BMI Common Prior to Dementia Diagnosis

Abstract

Back to table of contents Previous article Next article Clinical and Research NewsFull AccessDrops in Blood Pressure, BMI Common Prior to Dementia DiagnosisNick ZagorskiNick ZagorskiSearch for more papers by this authorPublished Online:23 Oct 2018https://doi.org/10.1176/appi.pn.2018.9a16AbstractA study that tracked seniors over 14 years is one of the first to explore how temporal changes in metabolic risk factors affect dementia risk.Metabolic problems are a known risk factor for dementia, but studies examining the association between metabolic status at certain ages and dementia risk have found varied results. High blood pressure and low blood pressure at certain ages have both been linked with dementia risk, as have obesity and being underweight.iStock/Sasha_SuziIn a study published in JAMA Psychiatry, researchers at the University of Bordeaux in France described how rather than examining the relationship between metabolic status at a specific age and dementia risk, they tracked the trajectories of these risk factors. They found evidence to suggest that exaggerated drops in body mass index (BMI) and blood pressure could signify oncoming dementia. They also reaffirmed that high blood glucose in older age is a significant dementia risk factor.The findings were based on analysis of health data from nearly 4,000 individuals who were part of the Three-City (3C) study. The study followed adults aged 65 and older in three French cities (Bordeaux, Dijon, and Montpelier) for 14 years to ascertain connections between heart disease and dementia.The research team identified 841 people in the 3C cohort who developed dementia at some point during the study (the average length of time to diagnosis was about eight years). The researchers then tried to match each person with dementia with four control individuals with similar demographics at the time of diagnosis; they successfully matched 785 dementia cases with 3,140 controls for the final analysis.The researchers then plotted out all prior assessments of BMI; systolic and diastolic blood pressure; and high-density and low-density lipoprotein cholesterol (HDL-C and LDL-C), triglyceride, and blood glucose levels for these 3,925 people.The metabolic trajectories revealed that people who developed dementia showed much steeper declines in BMI in the years preceding their diagnosis, with the most rapid weight loss starting at about seven years before diagnosis. Over the 14-year period, the average BMI of dementia patients dropped from 26.1 to 24.8, whereas BMI in controls only dropped from 25.7 to 25.3. People who developed dementia also experienced a greater drop in blood pressure over time compared with controls. Although both groups of patients experienced rising blood glucose level with age, those with dementia had consistently higher glucose levels over the 14-year period. Lead study author Maude Wagner, M.P.H., of the University of Bordeaux said that the changes seen in dementia patients likely represent reverse causation—that is, subtle cognitive decline may be accelerating normal metabolic changes. In the case of BMI, early dementia may cause someone to eat less, which would increase age-related weight loss. Likewise, some research has suggested that early-stage dementia disrupts brain processes involved in blood pressure regulation.Because low blood pressure reduces the delivery of oxygen to the brain, Wagner and colleagues noted that it is also possible that lower blood pressure contributes to dementia.“This study reinforces that the relationship between metabolism and dementia is complex and highly dependent on timing,” Gary Small, M.D., director of geriatric psychiatry at the David Geffen School of Medicine at the University of California, Los Angeles, told Psychiatric News. Even so, he cautioned that it’s too soon for clinicians to make predictions using these measures.“We need more longitudinal studies to try to tease out this gray area of what changes are cause versus effect,” he said. The 3C is conducted under a partnership agreement between the Institut National de la Santé et de la Recherche Médicale (INSERM), the University of Bordeaux, and Sanofi. ■“Evaluation of the Concurrent Trajectories of Cardiometabolic Risk Factors in the 14 Years Before Dementia” can be acccessed here. ISSUES NewArchived