Schizophrenia is a mental health disorder in which there is a strong disconnect between a person’s thoughts, emotions, and behavior. Those thoughts and feelings may suggest a departure from reality.

Dementia, on the other hand, represents diminished memory and difficulties with concentrating, decision making, judgment, and other thinking skills.

Dementia, which is largely driven by advancing age, is also much more common, affecting about 16 percent of adults over the age of 80. Schizophrenia is rare, affecting less than 1 percent of the global population, according to the World Health Organization.

Some symptoms of schizophrenia and dementia are similar. There’s some evidence that people with schizophrenia may face a greater risk of dementia.

While you cannot necessarily prevent schizophrenia, some treatments can reduce symptoms and manage the condition. You cannot always prevent dementia either, but there are several risk factors you can control to lower the odds of cognitive decline.

Unlike dementia, which usually develops late in life, schizophrenia typically first appears in your teens or 20s. Men are somewhat more likely than women to have schizophrenia. Men also tend to receive a diagnosis at a younger age than women.

Schizophrenia is the result of changes in brain structure and chemistry. This means that a person with the disorder has an increased risk of other brain-related complications. These include:

  • depression
  • sensory perception
  • cognitive decline

Cognitive decline can eventually lead to dementia.

A 2018 study suggests that people with schizophrenia have a nearly twofold increased risk of dementia after adjusting for other standard risk factors.

Similarly, a 2019 study notes that older, otherwise healthy men with a psychotic disorder, such as schizophrenia, are three times as likely as men without psychosis to develop dementia.

A 2018 review explored possible explanations for the link between schizophrenia and dementia. It reviewed six major studies involving more than 5 million adults, including more than 200,000 who had dementia. One suggestion was that brain changes responsible for schizophrenia might also contribute to dementia.

Researchers also noted that long-term use of antipsychotic medications might increase the risk of dementia. Other common behaviors in people with schizophrenia increased their risk for dementia, including:

  • alcohol misuse
  • smoking
  • a sedentary lifestyle

Late onset schizophrenia

Symptoms of schizophrenia usually appear in young adulthood. But if they emerge in your 40s or later, the condition is known as “late onset schizophrenia.”

It’s not clear why an individual would develop schizophrenia later than other people, but it is clear that certain symptoms tend to be more pronounced in certain groups.

For example, people with late onset schizophrenia may experience hallucinations or delusions more than younger people with the condition.

However, a 2019 report by the American Psychological Association suggests that cognition problems may be less common in people with late onset schizophrenia.

But for people who receive a diagnosis of very late onset schizophrenia — when symptoms appear after the age of 60 — the risk of subsequent dementia is significant.

Certain symptoms of schizophrenia and dementia are the same, which can sometimes make it difficult for doctors to make an accurate diagnosis.

But since schizophrenia usually starts at a much younger age, some of those shared symptoms can be correctly assigned to the disorder rather than the onset of cognitive decline.

The chart below includes symptoms that are often present in people with schizophrenia or dementia, or both:

cognitive declineyesyes
disorganized speechyesyes
withdrawal from friends and typically enjoyable activitiesyesyes
inflated self-imageyesno
movement and balance troublenoyes
difficulty finding the right word to identify or describe somethingnoyes
repeating questionsnoyes

Before doctors diagnose schizophrenia or dementia, they’ll try to rule out other causes of symptoms. This involves checking for, among other things, medication or narcotics side effects and evidence of a stroke or brain tumor.

Because there’s no blood test or other definitive screening tool to diagnose schizophrenia, a doctor must evaluate your symptoms. This process includes conversations with you and your family members or friends.

According to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), a diagnosis of schizophrenia requires that at least two of the following symptoms occur regularly and interfere with everyday functioning:

Diagnosing dementia also involves a review of symptoms and, when possible, input from people close to you who can speak to noticeable changes in cognition. Doctors will also test:

  • cognition
  • memory
  • problem solving
  • communication
  • math skills

Brain scans can also reveal changes in brain structure and volume, which may help form a diagnosis.

If signs of dementia are present, but schizophrenia is suspected, doctors will focus on symptoms of psychosis. If psychosis is present, doctors may decide that schizophrenia is the cause of the cognitive decline, and treatment decisions will follow.

It’s possible for dementia to develop independently of schizophrenia, especially among older adults. For example, a person may develop vascular dementia or Alzheimer’s disease regardless of whether or not they have schizophrenia.

It’s not always clear why one person develops dementia while someone else of the same age and health profile does not. Like schizophrenia, dementia risk can be affected by genetics and environmental factors.

But according to the Lancet Commission, an international panel of health experts, an estimated 40 percent of dementia cases may be attributed to 12 modifiable risk factors. Adjusting your lifestyle to account for these risk factors does not guarantee you will prevent dementia.

Still, you may be able to lower your risk of cognitive decline or delay its onset. The 12 risk factors are:

Treatment for schizophrenia depends largely on how often you experience symptoms and how intense they are. Antipsychotic medications, taken as pills or liquids, can help reduce the intensity of symptoms.

Injectable medications administered once or twice each month may also be appropriate, especially for people who find it hard to stick to a daily medication schedule.

The National Institute of Mental Health recommends using clozapine to treat people whose symptoms do not improve with other antipsychotics.

Cognitive behavioral therapy and cognitive remediation interventions may help ease certain negative symptoms and cognitive dysfunction, especially when combined with medication use.

Psychosocial training may help some people with schizophrenia function in everyday settings, including school, work, and family situations. Family education and support are also important for a well-rounded treatment plan.

People dealing with schizophrenia and dementia can sometimes deny the severity or even the presence of symptoms. This can make it difficult for doctors to make a proper diagnosis. But a correct diagnosis is critical to managing symptoms.

Dementia is a progressive disease, meaning it will get worse over time and could be fatal. It can also contribute to other health conditions that ultimately lead to death.

Schizophrenia is not fatal, but it needs ongoing treatment to keep it from interfering too much with your physical health and well-being.

In both cases, the support of partners, family, and friends can make a big difference in how these conditions progress and whether you can maintain a decent quality of life.