Home > Diagnosis, Psychological issues > Dementia and Schizophrenia

Dementia and Schizophrenia

Image courtesy Stuart Miles @ http://www.freedigitalphotos.netFrequently, in my practice as a speech-language pathologist, I have encountered individuals who carry a diagnosis of dementia as well as a psychiatric disorder such as schizophrenia.  I’ve often wondered which came first — kind of a “chicken or the egg” type of question.  So today I decided to do a little research, and I thought I would share with my readers a little bit of what I found.  I’ll start with a brief discussion of the early work of classifying schizophrenia as a distinct disorder, leading up to how the two disorders have been found to be distinct from each other, and yet at times connected.  Please bear in mind that I am not a psychologist or psychiatrist.

History is full of descriptions of people who appeared to show symptoms consistent with what we now call schizophrenia.  In 1886 a Swiss physician named Heinrich Schule, who worked in an asylum, described a disorder which he termed dementia praecox (early-appearing dementia).  He used this term to refer to individuals who showed symptoms of an acute dementia early in life, seemingly hereditary in nature.

In 1899, Emil Kraepelin differentiated between dementia praecox and mood disorders, arguing that dementia praecox was caused by a metabolic process which began relatively early in life and affected the entire body, eventually leading to significant deterioration and loss of function.  Interestingly, this was several years before Alois Alzheimer described the form of dementia which later came to bear his name.  Kraepelin pointed out that dementia praecox primarily affected younger patients, whereas Alzheimer’s disease was found mainly in the elderly.

A number of physicians and other researchers continued the work of describing this new disorder, and differentiating it from other maladies.  Eugen Bleuler first coined the term schizophrenia in 1908, in an attempt to describe the separation of function between personality, thinking, memory, and perception.  He reasoned that the disorder was not a true dementia, as some of his patients improved rather than deteriorated.  Work has continued in this area, until now dementia and schizophrenia are generally regarded as two distinct disorders.

That said, it has long been recognized that cognitive impairments can exist in persons diagnosed with schizophrenia.  In May of 2000, a study was conducted to determine whether this phenomenon was due to the schizophrenia, or to a separate dementia-causing illness.  A group of institutionalized patients who were diagnosed with chronic schizophrenia were identified, aged 65 years or younger, who did not display any organic risk factors for dementia.  They were screened for the presence of disorientation, and those who showed this trait were studied further — neuropsychological testing, physical examinations, and neuroimaging, as well as a description of behaviors by caregivers.  In every case where a study participant was identified as having disorientation, the presence of a separate entity causing the cognitive symptoms was identified, of a type similar to frontotemporal dementia, with pervasive deficits in memory and executive function noted in particular.

Other experts report that schizophrenia may lead to a true dementia in later life, either as a direct consequence of the disease itself, or as a reversible side-effect of medications used to treat it.  It has been shown that some persons with schizophrenia do demonstrate a progressive deterioration in the ability to perform basic activities of daily living.  Some individuals develop a form of cognitive impairment many years after the onset of schizophrenia, which is invariably terminal in nature (as with other forms of dementia).  Others show a form of dementia which may potentially be reversible, and is related to the psychopathology associated with periods of active schizophrenia.

Researchers showed renewed interest in the relationship between schizophrenia and dementia with the development of improved neuroimaging techniques in the 1970s.  Early studies showed that schizophrenic patients with long-standing significant intellectual impairments showed widespread cortical atrophy.  Subsequent post-mortem studies confirmed the loss of tissue in the anterior and mid-temporal lobes of the brain.

Chronic schizophrenia patients who also demonstrate dementia tend to show the following symptoms.  They often will underestimate their own ages, by about 5 years or more.  They show an overwhelming lack of initiative, at times spending hours in bed staring at the ceiling.  Orientation is often relatively intact, and they are usually able to respond appropriately to simple questions.  They often demonstrate involuntary movements of the head and face, or even of the entire body.

Some persons with schizophrenia are said to demonstrate a “pseudodementia,” especially in those who are significantly depressed.  Treating this depression with medication appears to remedy this situation in most cases.  However, it has been argued that these people should be treated as having dementia while the symptoms are present.

There are some cognitive symptoms which are judged to be characteristic of many individuals diagnosed with chronic schizophrenia, and which are not determined to be due to an accompanying dementia.  These symptoms include difficulties with attention and executive functioning, as well as learning and memory, with verbal knowledge and visual perception remaining relatively intact.

Research in all of these areas is currently on-going, with scientists continuing to work toward making more definite distinctions between the disorders of schizophrenia and dementia, as well as better identifying physical and cognitive characteristics of both conditions — and treatment of the same.  The significance for me, and for other rehabilitation professionals, is to understand that some schizophrenic persons can demonstrate symptoms that may indeed be related to a dementing illness.  A complete cognitive evaluation can provide information to assist the patient’s physician in making an appropriate diagnosis, and also assist in determining a plan of treatment.

Persons who have been diagnosed with schizophrenia, and their loved ones/caregivers, should also take note that physical/cognitive symptoms may or may not be directly related to the disorder.  Any change in behavior should lead to a consultation with the person’s physician, which may lead to further evaluation to determine the source of this change.  There are health care professionals who can help to develop strategies for dealing with this behavior, and helping to understand it.


Wikipedia:  History of Schizophrenia




  1. Sarah Peel
    August 10, 2014 at 10:41 AM

    Hello, thank you for this article, this information is very helpful. Myself and my parents are very concerned about my brother who was diagnosed with schizophrenia at 17 yrs old and is now 42 yrs old. He lives at home with my parents. We have become increasingly concerned about his mental health and wellbeing over the past few years but have received little support or assistance from his consultants when we have tried to explain some of his behaviour. This is possibly because his symptoms do not seem to correspond with symptoms of schizophrenia or an episode and he has been stable on Clozaril for many years. However, from my own observations and things my parents have observed, he may be showing symptoms of dementia. We have had concerns over the years that either the disease itself or the long term use of medication is leading to brain damage that is affecting other areas of his cognitive function. We are currently waiting to see his consultant for some help, advice and hopefully an assessment. The possibility of him having developed dementia is something to be considered. Many thanks. Sarah

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