Can Schizophrenia Increase the Risk for Dementia?

A chronic mental disorder, schizophrenia causes people to experience distortions of reality, usually in the form of delusions and/or hallucinations. Apart from experiencing a combination of delusions and hallucinations, people with schizophrenia are also prone to having extremely disordered behavior and thinking that affects their day-to-day functioning. This prevents them from leading a normal life. Signs and symptoms of schizophrenia vary from person to person but usually involve hallucinations, delusions, disorganized speech, and an impaired ability to function.  According to the American Psychiatric Association, it is estimated that schizophrenia affects less than one percent of the population in the United States.^(1,2,3)

Schizophrenia can develop in men and women both, regardless of their age. While men usually start to develop the symptoms of the disorder in their late teens or early 20s, women start showing the symptoms in their late 20s and early 30s.^(4,5,6)

Meanwhile, dementia is a serious mental condition that is caused by brain injury or disease, which impacts a person’s ability to think, remember, and even behave normally. Dementia is characterized by diminished memory and challenges in concentrating, decision making, judgment, and other thinking skills as well. Dementia is typically driven by advancing age, and it is more common than schizophrenia. According to the Population Reference Bureau (PRB), dementia is believed to affect around 16 percent of adults over the age of 80 years.^(7,8,9)

Several of the symptoms of dementia are similar to those of schizophrenia. There is some evidence that indicates that people with schizophrenia are likely to face a higher risk of developing dementia. While it is not possible to prevent schizophrenia, there are certain treatments that can reduce the severity of the symptoms and help manage the condition. Neither is it possible to prevent dementia, but again, there are numerous risk factors that you can control to reduce the chances of cognitive decline.

Unlike dementia, which tends to develop later in life, schizophrenia can first appear during the teenage years or in your 20s. Men are known to be more likely than women to develop schizophrenia.⁽¹⁰⁾ Men are also more likely to receive the diagnosis of schizophrenia at a younger age than women.

Schizophrenia happens due to an alteration in brain chemistry and structure. This means that a person with schizophrenia has a greater risk of also developing other brain-related complications. These may include:

• Cognitive decline, which can eventually lead to dementia
• Depression
• Sensory perception

A 2018 study out of Taiwan showed that people with schizophrenia have almost a twofold higher risk of developing dementia after making the necessary adjustments for other standard risk factors.⁽¹¹⁾ Similarly, another 2019 study carried out by the James Cook University in Australia found that older but otherwise healthy men who have a psychotic disorder, such as schizophrenia, were three times more likely than men without psychosis to develop dementia.⁽¹²⁾

In 2018, a review looked at the possible reasons for the association between schizophrenia and dementia. The review looked at six major studies that involved over five million adults, including over 200,000 participants who had dementia. One possible suggestion was that the brain changes responsible for causing schizophrenia may also cause the development of dementia.⁽¹³⁾

Researchers have also found that the long-term use of antipsychotic medications for the treatment of schizophrenia increases the risk of dementia. Some other common behaviors in people who have schizophrenia that increases their risk of developing dementia include:

• A sedentary lifestyle
• Alcohol abuse
• Smoking
• Drug abuse

While the symptoms of schizophrenia usually appear in young adulthood, but in some cases, they may start showing up in your 40s or even later. This condition is known as late-onset schizophrenia, and it is not known exactly why a person would suddenly go on to develop schizophrenia at a later age than other people.^(14,15) It is believed that certain symptoms of late-onset schizophrenia tend to be more pronounced in certain groups of people.

For example, people who are diagnosed with late-onset schizophrenia tend to experience delusions or hallucinations more than those who are diagnosed with the condition at a younger age.

According to a 2019 report by the American Psychological Association, cognition problems are known to be less common in people who are diagnosed with late-onset schizophrenia.⁽¹⁶⁾

Nevertheless, for those who have received a diagnosis of very late-onset schizophrenia, when symptoms start appearing after the age of 60, are at significant risk of developing dementia as well.⁽¹⁷⁾

There are some symptoms that are similar between both schizophrenia and dementia. This sometimes makes it difficult for doctors to come up with an accurate diagnosis. However, since schizophrenia tends to usually begin at a much younger age, many of these shared symptoms between the two disorders can be correctly assigned to schizophrenia instead of being attributed to the onset of cognitive decline linked with dementia.

The table below shows which symptoms are usually present in people with schizophrenia and dementia and which are present in both conditions.

Before doctors diagnose either of these two conditions, they will first try and rule out the other causes of your symptoms. This involves checking for side effects of medications or narcotics, as well as evidence of a brain tumor or stroke.

Since there is no blood test or a definitive screening test that can help diagnose schizophrenia, a doctor has to be very careful while evaluating the symptoms. This process also includes hearing the conversations between you and your friends and family members.

According to the guidelines of the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), a diagnosis of schizophrenia needs to have at least two of the following symptoms that occur regularly and interferes with day to day functioning:⁽¹⁸⁾

• Hallucinations
• Delusions
• Negative symptoms
• Disorganized or catatonic behavior
• Disorganized speech

Diagnosing dementia also involves a thorough review of all symptoms and, whenever possible, input from the people close to you who can attest to the noticeable changes in cognition and behavior. A doctor will also test the following before making a diagnosis:

• Math skills
• Memory
• Cognition
• Communication skills
• Problem solving skills

In some cases, brain scans can show certain changes in brain volume and structure, which may help conclusively provide a diagnosis.

If signs and symptoms of dementia are present but schizophrenia is majorly suspected, doctors will focus on the symptoms of psychosis. And if psychosis is also present, doctors may decide that the cognitive decline is being caused by schizophrenia, and the treatment decisions will be taken accordingly.

Of course, it is also possible for dementia to develop without the presence of schizophrenia, especially in older adults. For example, a person may develop Alzheimer’s disease or vascular dementia regardless of whether they have schizophrenia or not.^(19,20)

It is not always known why one person develops dementia while another person of the same age and health profile does not get the illness. Similar to schizophrenia, the risk of dementia is also affected by environmental and genetic factors.

However, according to an international panel of leading health experts known as the Lancet Commission, it is estimated that 40 percent of all dementia cases are attributed to 12 modifiable risk factors. One of the biggest things you can do to cut down your risk of developing dementia is to adjust your lifestyle to take into account these risk factors and reduce your risk.⁽²¹⁾ However, there is still no guarantee that you will be able to prevent the onset of dementia.

Still, it might be possible to reduce the risk of cognitive decline or at least delay its onset by reducing these 12 risk factors, including:

• Obesity
• High blood pressure
• Heavy alcohol intake
• Smoking
• Less education
• Hearing loss
• Head injury
• Depression
• Diabetes
• Air pollution
• Physical inactivity
• Social isolation

The exact treatment for schizophrenia depends on how regularly you experience the symptoms and how severe these symptoms are. Antipsychotic medications, to be taken as pills or in liquid form, are the most common form of treatment, and these can help reduce the severity of your symptoms.

Some people may also find relief by taking injectable medications that are administered once or twice every month. This is ideal for those people who find it challenging to follow a daily schedule of medication.

According to the National Institute of Mental Health, it is recommended to use clozapine for treating people whose schizophrenia symptoms do not get better with the use of other antipsychotics.⁽²²⁾

Cognitive-behavioral therapy, in combination with other cognitive remediation interventions, can help relieve some of the negative symptoms and cognitive dysfunction, especially when they are administered together with medications.

Psychosocial training is also used for those people who find it difficult to function in everyday settings, such as in school, work, or family situations. Remember that the support of family and friends, along with the support of loved ones, is very important to achieve a well-rounded treatment plan for schizophrenia.^(23,24)

People living with both schizophrenia and dementia sometimes end up denying the severity or the presence of their symptoms. This often makes it challenging for doctors to make a correct diagnosis. However, in order to manage your symptoms, having an accurate diagnosis is absolutely critical.

Remember that dementia is a progressive disease, which means that it gets worse over time, and can also prove to be fatal. Dementia can also be a contributing factor to other medical conditions that ultimately cause death.

On the other hand, schizophrenia is not a fatal condition, but it needs to be controlled with ongoing treatment to prevent it from interfering with your daily life, your physical health, and overall well-being.

In the case of both these disorders, the support of family and friends is known to make a huge difference in how the conditions progress and on the quality of life.

References:

Also Read:

• Recovery from Schizophrenia: 4 Tips for Proper Recovery
• How to Help Someone with Schizophrenia?
• Early Onset Schizophrenia or Pediatric Schizophrenia or Schizophrenia in Children: Causes, Symptoms
• Treatment, Recovery Period for Early Onset Schizophrenia or Pediatric Schizophrenia or Childhood Onset Schizophrenia
• Risk Factors and Diagnosis of Childhood Onset Schizophrenia or Early Onset Schizophrenia or Pediatric Schizophrenia
• Paranoid Schizophrenia: Causes, Symptoms, Treatment, Recovery, Prognosis, Effects
• Catatonic Schizophrenia: Causes, Signs, Symptoms, Diagnostic Criteria, Diagnosis