The increased blood pressure of hypertension causes structural damage to delicate tissues throughout the body, particularly in the brain. Beyond the matter of an increased pace of rupture of capillaries, killing tiny volumes of brain tissue, the blood-brain barrier is disrupted by pressure damage, allowing unwanted molecules and cells into the brain to provoke chronic inflammation and disruption of function. Blood pressure is so influential on health that lowering blood pressure via antihypertensive medication, an approach that does not in any way address the underlying causes of the problem, produces a reduction in mortality that is in the same ballpark as that resulting from exercise programs.
Individuals who are diagnosed with high blood pressure at ages 35-44 had smaller brain size and were more likely to develop dementia compared to people who had normal blood pressure, according to new research. Hypertension is very common in middle-aged people (45-64 years), and early onset high blood pressure is becoming more common. Although the association among hypertension, brain health, and dementia in later life has been well-established, it was unknown how age at onset of hypertension may affect this association. If this is proven, it would provide some important evidence to suggest earlier intervention to delay the onset of hypertension, which may, in turn, be beneficial in preventing dementia.
The researchers analyzed data from participants in the UK Biobank, a large database containing detailed anonymous health information of about half a million volunteer participants in the United Kingdom. To determine brain changes, they compared magnetic resonance imaging (MRI) measurements of brain volume between two large groups of adults in the database: 11,399 people with high blood pressure diagnosed at different ages (younger than age 35; 35-44 years; and 45-54 years), and 11,399 participants who did not have high blood pressure, matched for age and multiple health-related variables. Participants entered the databank between 2006 and 2010, and they had MRI brain scans between 2014 and 2019.
In each diagnostic age category (from 35 to 54), the total brain volume was smaller in people diagnosed with high blood pressure, and the brain volume of several regions were also smaller compared to the participants who did not have high blood pressure. Hypertension diagnosed before age 35 was associated with the largest reductions in brain volume compared with controls. Among people with normal blood pressure readings at the time of their MRI scans, those who were previously diagnosed with hypertension at ages younger than 35 years old had smaller total brain volume compared to people with normal blood pressure who had never been diagnosed with hypertension.
The risk of dementia from any cause was significantly higher (61%) in people diagnosed with high blood pressure between the ages of 35 and 44 compared to participants who did not have high blood pressure. The risk of vascular dementia (a common form of dementia resulting from impaired blood flow to parts of the brain, as might happen after one or more small strokes) was 45% higher in the adults diagnosed with hypertension between ages 45-54 and 69% higher in those diagnosed between ages 35-44, compared to participants of the same age without high blood pressure.