Several studies suggest people with schizophrenia may have a higher risk of developing major neurocognitive disorder (MND). These two conditions also share some symptoms, which can complicate diagnosis.

Schizophrenia may increase a person’s risk of developing major neurocognitive disorder (MND), formerly called dementia. In fact, schizophrenia was once called “dementia praecox,” which means premature dementia.

Researchers are continuing to investigate whether schizophrenia is a risk factor for MND, a cause of MND, or whether one may help to predict the other.

Psychosis, a collection of symptoms and a core feature of schizophrenia, could be an early warning sign of MND. In some cases, MND causes schizophrenia-like symptoms in people with no prior history of schizophrenia.

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A 2021 Swedish population study suggests that people with very late-onset schizophrenia-like psychosis have a significantly higher rate of MND than the rest of the population.

Although schizophrenia is a clear risk factor for MND, a 2024 review suggests that various environmental and genetic factors can affect and contribute to this risk.

It is unclear whether schizophrenia causes MND, or if the two diseases share some other trait that makes them more likely to occur together. However, research has shown that MND does not increase the risk of developing schizophrenia.

Researchers also do not know if treating schizophrenia reduces the risk of MND.

Shared symptoms

Further complicating things, MND and schizophrenia share many symptoms, including:

This is especially true for certain kinds of MND, such as frontotemporal MND, which tends to appear earlier in life and which may mimic schizophrenia symptoms.

Some people with MND have symptoms of psychosis, a disconnection from reality, even before they develop other symptoms.

The 2021 study highlights the potential for people with a diagnosis of late-onset schizophrenia to actually have MND. This further illustrates the importance of a thorough medical evaluation that considers both diagnoses when people have psychosis symptoms.

Diagnosing both schizophrenia and MND can be challenging. The challenges increase when a person already has one of the two conditions.

There is no single definitive test for MND. While tests can show declines in cognitive function, they cannot conclusively prove that MND is the cause or determine the type of MND a person has. That said, they can help determine the most likely diagnosis.

Doctors typically use a combination of tests, such as bloodwork and brain scans, to look for MND markers, including signs of plaques in the brain.

However, not all people with MND develop brain signs of the disease, and some people with plaques or other symptoms do not have MND.

To diagnose schizophrenia, a doctor will assess a person’s medical history, family history, and symptoms. They may use blood tests or imaging tests to rule out other potential causes of a person’s symptoms.

Since MND and schizophrenia can share symptoms, it is important for anyone experiencing psychosis to work with a healthcare professional to find the underlying cause.

Both schizophrenia and MND affect thinking and behavior and may lead to false beliefs. Some important differences include:

  • Age of onset: Schizophrenia is most likely to develop in a person’s 20s. In contrast, the risk of MND increases with age. However, there are exceptions, such as very-late-onset schizophrenia and early onset MND.
  • Early symptoms: Memory and thinking difficulties tend to be the earliest symptoms in most types of MND. In schizophrenia, delusions and hallucinations may be more noticeable early in the disease.
  • Progression: MND is a progressive illness with no cure. Schizophrenia may worsen with time, but it is not inevitably fatal or progressive, and does not typically affect daily functions, such as bowel and bladder control.
  • MND types: There are many different types of MND, each with its own unique early symptoms. Some types, such as frontotemporal MND
  • Complications: MND affects various bodily systems, and complications tend to relate to this, such as injuries from falls, pneumonia, and inadequate nutrition. Schizophrenia complications are more often related to mental health.

Both schizophrenia and MND attack the brain, affecting a person’s ability to think clearly and engage in culturally typical behavior. Some important similarities between schizophrenia and MND include:

  • While there are different patterns to the average age of onset, both conditions can occur at any age.
  • The two conditions can occur together.
  • Both can cause problems with memory, executive functioning, and behavior.
  • Both conditions may cause psychosis, which means that a person believes things that are untrue or experiences things that are not there.
  • There is no cure for either condition, though both are treatable. Treatment for schizophrenia can help greatly reduce symptoms, while treatment for MND may slow or delay progression.
  • Both diseases can shorten a person’s life expectancy.
  • Both conditions are associated with other chronic medical illnesses, such as heart disease.

MND is a complex illness with genetic, developmental, and environmental influences. There is no strategy that can guarantee that a person will not develop dementia. However, some strategies may help reduce the risk, including:

  • Treat hearing loss as soon as possible, since hearing loss correlates with a higher risk of MND.
  • Do not smoke, or quit smoking.
  • Get regular exercise, especially in midlife and beyond.
  • Remain mentally and socially active by spending time with friends, doing challenging activities, and avoiding isolation.
  • Eat a balanced diet containing whole grains, fruits, and vegetables.

Various strategies can help a person manage symptoms of schizophrenia, including:

  • Seek care as soon as symptoms appear.
  • Take antipsychotic medication, and talk with a doctor about whether additional medications might be appropriate.
  • Tell a doctor about any treatment side effects. Additional drugs or changes in medication may help with these symptoms.
  • Try therapy with a psychotherapist who specializes in schizophrenia.
  • Find support to get a job and integrate into the community. Support groups, occupational training, and peer mentoring may all help.

Schizophrenia can relapse, so it is important to know the signs that the diagnosis is getting worse. This makes it easier for a person to promptly seek care.

Both schizophrenia and MND are chronic, incurable illnesses. However, people with either or both diseases can manage symptoms and improve their quality of life with the right medical care and social support.

Getting the correct diagnosis can prove challenging, especially for people who develop symptoms later in life or who have a long history of cognitive or mental health issues.

It is important to contact a neurologist with significant experience treating brain disorders to improve the odds of getting the right diagnosis.