Alzheimer’s disease and other progressive dementias are not the only cause of cognitive impairment. It is commonly known that as the heart goes, so goes the brain. An estimated 5 million Americans suffer from heart failure and this number is expected to double over the next 40 years (“Heart failure and cognitive dysfunction,” International Journal of Cardiology, 2014, 178, 12-23, PMID 25464210). Cognitive impairment is common in those with heart failure with a prevalence ranging from 25% to 75% with greater degree of heart failure associated with higher levels of cognitive impairment. Those in heart failure with a left ventricular ejection fraction of less than 45% are especially prone to cognitive impairment that is at least mild.

Cognitive impairment may involve any one or all of several brain functions. These include attention, memory, executive function, language, speed of thinking, and/or constructive ability. Heart failure causes hypoperfusion (decreased blood flow) of the brain, which reduces oxygen and delivery of glucose to the brain. This in turn may lead to the destruction of neurons. The risk for cognitive impairment in heart failure is greatest for those with diabetes, systolic blood pressure of greater than 180, or diastolic blood pressure less than 65. There does not appear to be an association with low systolic or high diastolic blood pressure.

There are a multitude of secondary effects of heart failure that may contribute alone or together to increase cognitive impairment. Among these factors is depression, which may be severe or mild. Many medications that regulate blood pressure and heart function have anticholinergic side effects that are notorious for inducing confusion. Diabetes is known to induce cardiomyopathy, heart disease, and hypoglycemia. Inflammatory cytokines are released and are associated with cognitive impairment. Homocysteine, an amino acid, is elevated in heart failure and associated with cognitive impairment and decline. Finally, atrial fibrillation is strongly associated with cognitive and functional decline if left untreated.

Cognitive impairment associated with heart failure has a number of consequences. It compromises the skills necessary to manage a complicated treatment routine including managing medications, tracking follow up appointments, and managing heart healthy diet. It also may compromise the ability to recognize symptoms in oneself. On a practical level these changes may impair IADLs like driving, managing finances, paying bills, or preparing meals. In the extreme, cognitive impairment may lead to hospitalization and increased mortality in heart patients, mortality in heart failure with cognitive impairment is 18% at one year versus 3% in those with normal mentation.

The bottom line is that heart disease adds cognitive burden that affects treatment and outcome. The cognitive changes may be subtle or obvious, temporary or persisting. Assessment of cognitive function is an essential component in managing and treating heart disease.