What's the difference between schizophrenia and Alzheimer's?

A fellow caregiver asked...

What's the difference between schizophrenia and Alzheimer's? I'm seeing some of the same symptoms, and am getting very scared.

Expert Answer

Kenneth Robbins, M.D., is a senior medical editor of Caring.com. He is board certified in psychiatry and internal medicine, has a master's in public health from the University of Michigan, and is a clinical professor of psychiatry at the University of Wisconsin-Madison. His current clinical practice focuses primarily on geriatrics. He has written and contributed to many articles and is frequently invited to speak on psychiatric topics, such as psychiatry and the law, depression, anxiety, dementia, and suicide risk and prevention.

Schizophrenia and Alzheimer’s Disease are both diseases of the brain that can cause dramatic symptoms. They are different in many ways, but there are some similarities. Both can be associated with psychotic symptoms. That is, they can include hallucinations or delusions. Hallucinations are false sensory perceptions, which can involve someone believing they are seeing things, hearing things, touching things, or smelling things, but these perceptions are not real. Delusions are fixed false beliefs, such as someone believing they are being followed, believing they are not human or believing they have a terminal illness, though there is nothing to support the accuracy of the beliefs. Furthermore, both diseases can interfere with thinking, as will be discussed below. Their differences, however, are far greater than their shared features.

Alzheimer’s Disease is the most common cause of dementia. It is the cause of about two thirds of dementia in this country. This is a disease that only rarely manifest itself before age 65. By the time people reach age 85, about 40% of people in this country can be diagnosed with this disease. Alzheimer’s Disease destroys brain cells and as a result, it causes progressive problems with memory and other cognitive functions. For example, it can cause problems with spatial orientation, reasoning, abstract thinking, language and planning. As it gets worse, it causes problems with social functioning, hobbies, work and even with performing activities of daily living. There are many psychological difficulties that are experienced by people with this disease. Depression is very common, especially early in the course of Alzheimer’s Disease. People can also become anxious, agitated, aggressive and psychotic as the illness progresses. These associated psychiatric difficulties can be treated, but unfortunately we do not know how the treat the pathologic process that causes this disease. There is a class of medications called cognitive enhancers that can slow the disease process, but only by months rather than years.

Schizophrenia is a psychotic illness that generally becomes manifest between the late teens and the early 30’s. The symptoms of schizophrenia include hallucinations and delusions, as well as difficulty organizing thoughts. Symptoms can also include a decrease in the ability to show or express emotion and problems with particular cognitive functions. These functions can include problems with attention, planning and organizing thoughts, and can include problems being able to use recently learned information. This loss of accessing recent memories is a relatively small part of the illness, whereas with Alzheimer's Disease, memory problems are fundamental to the illness. Fortunately, with schizophrenia we have medications that can treat the illness and markedly reduce the symptoms.