We turned to Gerard Sanacora, M.D., Ph.D., professor of psychiatry at Yale School of Medicine and director of the Yale Depression Research Program. He writes:
“The medical opinion on the connection between low blood pressure (hypotension) and major depressive disorder has vacillated over the years. Prior to the 1940s, it was common for physicians to ascribe mental symptoms such as lassitude, fatigue, dizziness, sleep disturbances, anxiety and depression to a ‘constitutional hypotension’ or a ‘hypotensive syndrome.’
“Studies at the time reporting symptoms of anxiety and depression to be associated with lower blood pressure measures fostered the general acceptance that low blood pressure was related to the syndrome. However, a series of reports highlighting the various health benefits of lower blood pressure measures and evidence that individuals with the highest levels of stamina and endurance actually maintained very low blood pressure, shifted the thinking of the field away from this belief.
“More recently, this association has been reexamined with a fresh perspective. Several studies conducted over the last decade have again reported a clear association between hypotension and symptoms of depression and anxiety, especially in the geriatric population.
“Of special interest, a large Norwegian study of 65,648 men and women found a significant association of low blood pressure with anxiety and depression. The investigators reported an approximately 40% increase in the risk for anxiety or depression in individuals with systolic blood pressure measures in the lowest 5% of the population. Although there are several potential variables that may account for this finding such as the gender, age, use of specific antihypertensive medications, and the general health of the low blood pressure subjects, considering these variables in the analysis did not change the significance of the association in the study. Thus, there is again an increasing belief that some form of relationship exists between very low blood pressures and depressive symptoms.
“It is important to be clear that the evidence of an association between low blood pressure and depressive symptoms does not mean hypotension is causing depression. The association only means that hypotension and depression are more commonly seen in the same individuals. However, there is now interest in identifying what could be some of the common mechanisms underlying this relationship including difference in physical activity and stress reactivity, altered neuroendocrine, immune and/or autonomic regulation, and possible dysfunction of neurotransmitter systems and brain circuits regulating processes such as blood pressure and mood within the brain.”