Normal pressure hydrocephalus (NPH) produces three hallmark symptoms: difficulty walking, cognitive decline, and loss of bladder control. These symptoms develop gradually, often over months or years, which is why NPH is frequently misdiagnosed as Parkinson’s disease, Alzheimer’s, or simply “getting older.” What makes NPH worth identifying is that it’s one of the few causes of dementia-like symptoms that can actually be treated and, in many cases, reversed.
NPH occurs when cerebrospinal fluid builds up in the brain’s ventricles, enlarging them and pressing on surrounding tissue. Unlike other forms of hydrocephalus, the fluid pressure measured during a spinal tap stays within normal range, which is where the condition gets its name. It primarily affects adults over 60.
Walking Problems Come First
Gait disturbance is the earliest and most prominent symptom of NPH, and it’s often the first thing that brings someone to a doctor. The walking pattern has distinct characteristics: slow speed, short steps, a wide stance, and feet that barely clear the floor. Some clinicians describe it as a “magnetic gait” because it looks as though the person’s feet are stuck to the ground.
People with NPH don’t swing their arms normally while walking. They tend to shuffle, and turning requires multiple small steps rather than a smooth pivot. Balance is poor, and falls become more frequent. This isn’t the same as the stiffness or tremor seen in Parkinson’s disease. NPH gait problems don’t respond to levodopa, the primary Parkinson’s medication, which is one of the key ways doctors distinguish the two conditions.
Gait is also the symptom most likely to improve with treatment. In a large analysis of over 4,800 patients who underwent surgical treatment, 72% showed gait improvement. Walking problems respond better than either cognitive or urinary symptoms, which is one reason early diagnosis matters so much.
Cognitive Changes That Mimic Dementia
The cognitive decline in NPH looks different from Alzheimer’s disease, though it’s easy to confuse the two. NPH primarily affects executive function: planning, organizing, multitasking, and processing speed. People become slower in their thinking and reactions. They may seem apathetic or disengaged, losing interest in hobbies or conversations. Short-term memory can suffer, but the severe memory loss and language breakdown typical of Alzheimer’s is less common in NPH.
Psychomotor slowing is a key feature. Tasks that once took minutes now take much longer, not because the person has forgotten how to do them, but because their brain processes information more slowly. Concentration drifts. Decision-making feels labored. Family members often describe the person as seeming “foggy” or “checked out” rather than confused in the way Alzheimer’s patients become confused.
These cognitive symptoms improve in roughly 50% of patients after treatment, a lower rate than gait improvement but still remarkable given that most forms of dementia have no effective reversal. The longer symptoms go untreated, the less likely they are to bounce back, which is why NPH is sometimes called a “treatable dementia” with a time-sensitive window.
Bladder Problems That Progress Over Time
Urinary symptoms in NPH follow a predictable progression. Early on, people notice they need to urinate more often than usual, or they feel sudden, hard-to-control urges. This can easily be dismissed as a prostate issue in men or a pelvic floor problem in women. Over time, those urges become harder to manage, and episodes of incontinence begin. In advanced cases, people lose bladder awareness entirely.
Fecal incontinence can also occur, though it’s less common and typically appears later in the disease course. Bladder symptoms improve in about 50% of surgically treated patients.
Why These Three Symptoms Appear Together
The enlarged ventricles in NPH sit near the center of the brain, and as they expand, they stretch and compress the nerve fibers that run along their walls. The fibers controlling leg movement and bladder function travel closest to the ventricle surface, which explains why walking and urinary problems tend to appear before cognitive changes. The cognitive symptoms emerge as the expanding ventricles put pressure on deeper brain structures involved in attention, processing speed, and motivation.
Not everyone develops all three symptoms at once. Gait problems alone are enough to raise suspicion, and many people present with only one or two of the three features, especially early on. The full triad, sometimes called Hakim’s triad after the neurosurgeon who first described the condition, is more common in later stages.
What Causes NPH
In most cases, the cause is unknown. This is called idiopathic NPH and accounts for the majority of diagnoses. Secondary NPH, which develops after a known brain event, has identifiable triggers. A review of the medical literature found that the most common causes of secondary NPH were bleeding around the brain (46.5% of cases), head trauma (29%), brain tumors (6.2%), brain infections like meningitis (5%), and stroke or related vascular events (4.5%).
How NPH Differs From Similar Conditions
NPH overlaps with several other conditions common in older adults, which is why it’s estimated that many cases go undiagnosed or are mislabeled. The distinctions matter because NPH is treatable while most look-alikes are not.
Parkinson’s disease also causes slow, shuffling movement, but it typically includes a resting tremor (shaking when the hands are still), muscle rigidity, and a characteristic forward-leaning posture. Parkinson’s symptoms improve with levodopa medication. NPH symptoms do not. Imaging can help too: specialized brain scans can detect changes in dopamine-producing areas that occur in Parkinson’s but not in NPH.
Alzheimer’s disease shares the cognitive decline, but Alzheimer’s memory loss tends to be more severe and progresses differently. People with Alzheimer’s lose the ability to form new memories early on and eventually struggle with language and recognition. NPH cognitive problems center more on slowness and poor executive function. Doctors can also analyze cerebrospinal fluid for protein markers that are characteristic of Alzheimer’s but absent in pure NPH.
How NPH Is Diagnosed
Diagnosis starts with brain imaging. On a CT or MRI scan, doctors look for enlarged ventricles that are out of proportion to the overall amount of brain shrinkage you’d expect for someone’s age. The standard measurement is called the Evans index: the ratio of the widest part of the front ventricles to the widest part of the inner skull. A ratio above 0.3 indicates definite ventricular enlargement. Normal values fall between 0.20 and 0.25.
Imaging alone isn’t enough, though. The critical diagnostic step is a spinal tap test, where a doctor removes a large volume of cerebrospinal fluid and then checks whether symptoms improve. About 61% of NPH patients show measurable gait improvement after this test, defined as at least a 10% increase in walking speed. A positive response strongly suggests the person will benefit from surgical treatment. A negative result doesn’t completely rule out NPH, but it makes the diagnosis less certain.
Treatment and What to Expect
The primary treatment for NPH is a shunt, a thin tube surgically placed to drain excess cerebrospinal fluid from the brain’s ventricles to another part of the body, usually the abdomen, where it’s naturally absorbed. This is a well-established procedure that has been performed for decades.
A meta-analysis pooling data from 54 studies and nearly 5,000 patients found that about 75% of people improve after shunt surgery. Gait sees the greatest benefit (72% improvement rate), while cognitive and urinary symptoms each improve in roughly 50% of patients. People who are diagnosed and treated earlier generally see better outcomes, particularly for cognitive symptoms.
The procedure isn’t without risks. Complications occur in about 21% of cases, and around 15% of patients need a follow-up surgery to revise or replace the shunt. Common issues include the shunt draining too much or too little fluid, infection, or the tubing shifting out of position. Despite these numbers, shunting remains the standard of care because the potential for meaningful recovery is significant, especially given that the alternative is progressive decline.