3 Ways Normal Pressure Hydrocephalus Differs from Alzheimer’s Disease

An elderly patient presents with confusion and forgetfulness, common symptoms of old age. But upon further examination, the patient describes bouts of incontinence and has difficulty walking. She could be suffering from Alzheimer’s disease…or it could be idiopathic Normal Pressure Hydrocephalus (iNPH), a brain disorder that goes largely undiagnosed. In fact, more than 700,000 Americans have NPH, according to estimates by the Hydrocephalus Association, but fewer than 20% receive a correct diagnosis.

NPH can either be categorized as idiopathic NPH (iNPH), which has no known cause, and secondary NPH, which typically occurs with conditions such as subarachnoid hemorrhage or infectious meningitis. iNPH is a clinical diagnosis based on medical history, neurologic examination, and brain imaging with CT or MRI that most often occurs in people over the age of 55. It affects men, women, and people of all races equally.

“It’s the constellation of symptoms together with findings of increased cerebral spinal fluid on imaging that should definitely raise the suspicion of this condition that is often misdiagnosed,” says Abhay Moghekar, research director of Cerebrospinal Fluid Center at Johns Hopkins Medicine, in a recent video for the Hydrocephalus Association.

Because patients often go months, even years, before an NPH diagnosis, the first step is to get a scan to determine if a patient has an excess of cerebral spinal fluid, according to Dr. Mark Luciano, a neurosurgeon and director of the Cerebrospinal Fluid Center.

“The image really becomes the gateway to the possibility of ruling out,” he comments in the Association’s video. “It may be that the image shows no hydrocephalus symptoms, and it’s correct to look down these other directions. If it shows a reasonable collection of fluid, then hydrocephalus should be kept in mind.”

A correct NPH diagnosis may be crucial in cases of suspected iNPH, because medical intervention can sometimes reverse the effects iNPH has on patients’ quality of life. In addition, the earlier an iNPH diagnosis, the better chance a patient will have for successful treatment. Left untreated, iNPH symptoms will usually become worse and can lead to seizures and brain damage.

Here are 3 ways iNPH differs from Alzheimer’s disease:

1. iNPH and Alzheimer’s affect different areas of the brain.

iNPH affects the brain’s frontal lobe, responsible for voluntary movement, speech, making decisions, and processing information. Alzheimer’s, on the other hand, shows initial damage in the hippocampus and the entorhinal cortex, parts of the brain responsible for forming memories.

2. The order of symptoms in iNPH and Alzheimer’s is often different.

With iNPH, the earliest symptom is typically a change to a patient’s gait, which can range from a mild imbalance to being unable to walk or stand. Some patients might report a wide, slow, shuffling walk, while others may say that it feels like their feet are glued to the floor. Either way, it can become difficult for patients to lift their feet over stairs and curbs, leading to more falls.

As iNPH progresses, symptoms may include dementia and/or urinary incontinence. Dementia can range from patients losing interest in daily activities to difficulty performing routine tasks and short-term memory loss. Urinary incontinence can include having to go more often and more urgently to a complete loss of bladder control.

Meanwhile the onset of Alzheimer’s disease commonly presents when a patient begins to forget familiar words or the location of everyday objects. As the disease progresses, symptoms may include a patient confusing words, becoming angry or frustrated, and even acting differently (refusing to bathe, for example). They may have issues with bladder control or wander away from home. In late-stage Alzheimer’s, patients may struggle with walking, sitting and swallowing, and generally require around-the-clock care.

3. iNPH can be treatable, while Alzheimer’s disease is not.

When iNPH is diagnosed, surgical intervention is sometimes used to divert the excess cerebrospinal fluid (CSF) to another part of the body. While success varies according to what caused the iNPH, extent of symptoms, and how quickly the condition is diagnosed and treated, recent guidelines from the American Academy of Neurology found that surgery is possibly effective in iNPH with a 96% chance subjective improvement and a 83% chance improvement on timed walk test at 6 months.

When a patient is diagnosed with Alzheimer’s disease, medication can help alleviate the symptoms such as improving focus and mental function, managing behavioral symptoms, and improving quality of sleep. Yet there is no cure for Alzheimer’s disease or a way to stop or slow its progression.