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How does the doctor know if you really have dementia? Diagnosing dementia depends on both objective criteria and clinical judgment, but there is a process to making the diagnosis.

There is an orderly process to the diagnosis of dementia. Doctors consider whether symptoms are likely to be a one-time thing or something chronic. They then look for causes of disability that are explained by changes to the brain.

Dementia is a term that has been replaced by the more modern diagnosis major neurocognitive disorder. Just as mild dementia used to be known as mild cognitive impairment, the earlier stages of dementia are now diagnosed as a minor neurocognitive disorder. The American Psychiatric Association changed the terminology because "demented" literally means "without a mind," and people who have dementia still have minds, they just have challenges, sometimes severe challenges, in their daily lives. But you can still use the term "dementia" and doctors will know what you're talking about. 

How doctors recognize dementia in the ER

An emergency room physician treating a patient in a psychiatric crisis will often look for signs of delirium versus signs of a major neurocognitive disorder, still commonly called dementia


  • Presents acutely. The symptoms arise suddenly.
  • Involves disturbances of perception. There may be misinterpretations, illusions, and visual hallucinations.
  • Causes sudden mood swings. Abnormal thinking and behavior may fluctuate wildly over the course of the ER visit.
  • Comes with incoherent, pressured, nonsensical, perseverating (repetitious), or rambling speech.
  • May be hypoactive or hyperactive. Some people who are delirious may appear to be in a stupor. Others may be hypervigilant, agitated, and hallucinating.

In contract, dementia:

  • Presents as part of chronic pattern of behavior.It is associated with persistent problems with work, living conditions, and social relationships.
  • Is less likely to involve hallucinations, but there may be delusional interpretations of sensory input. People with dementia may "see" the world the same way everyone else does, but they may reach very different conclusions about it.
  • May be accompanied by major depression. In the earlier stages of dementia, people may try to conceal their condition. The inability to present as normal may lead to depression. The depression itself can cause dementia-like symptoms.
Sometimes older people come in to the ER, or are sent to the ER, with depressed mood, hopelessness, and suicidality. They may appear to have dementia, but their symptoms are resolved when they are treated with depression. This condition is known informally as "pseudo-dementia" (false dementia). It is important to distinguish depression and dementia. But sometimes a series of admissions for memory loss points to multiple small strokes, which accumulate to cause the symptoms of vascular dementia.

How do psychiatrists diagnose 'dementia'?

In the psychiatrist's office, the major diagnostic criterion for a "major" neurocognitive disorder, what used to be termed dementia, is whether or not the condition interferes with the patient's activities of daily living. The psychiatrist considers:

  • Complex attention, which includes attention span, divided attention, sustained attention, and information processing speed.
  • Executive function, which includes decision making, planning, working memory, responding to feedback, inhibition (deferred gratification), and mental flexibility.
  • Language, which includes the ability to name objects and find words, fluency, grammar, syntax, fluency, and receptive language (the ability to get information from both words and gestures).
  • Learning and memory, which includes cued recall, free recall, recognition memory, long term memory, and implicit learning.
  • Perceptual-motor function, which includes the ability to interpret visual inputs and motor coordination.
  • Social cognition, which includes recognizing one's emotions and insight.

Any diagnosis of major neurocognitive disorder requires deficits in one or more of the cognitive domains listed above. Any deficit must be so severe that it interferes with the ability to live independently. And the deficit or deficits must not be attributable to another disease.

Major neurocognitive impairment (dementia) does not necessarily involve memory loss.

How do law enforcement officials and social services workers recognize dementia? The police and adult protective services workers will defer to a medical diagnosis, but the decision to require a medical diagnosis also requires a process. The question usually is whether an arrestee or a person reported to social services can understand decision making, communicate the decisions they make, and use information appropriately. These are judgment calls that lead to a voluntary medical diagnosis process, or a hearing before a judge.

Diagnosing subtypes of neurocognitive impairment

Along with a psychiatric exam to determine whether the impairment is "major" or "minor," there is a neurological exam to ascertain the physical causes of the disease. Among the possible diagnoses listed in the DSM-5 are:

  • Major or Mild Neurocognitive Disorder Due to Alzheimer’s Disease 
  • Major or Mild Frontotemporal Neurocognitive Disorder 
  • Major or Mild Neurocognitive Disorder With Lewy Bodies 
  • Major or Mild Vascular Neurocognitive Disorder 
  • Major or Mild Neurocognitive Disorder Due to Traumatic Brain Injury  Substance/Medication-Induced Major or Mild Neurocognitive Disorder 
  • Major or Mild Neurocognitive Disorder Due to HIV Infection 
  • Major or Mild Neurocognitive Disorder Due to Prion Disease 
  • Major or Mild Neurocognitive Disorder Due to Parkinson’s Disease 
  • Major or Mild Neurocognitive Disorder Due to Huntington’s Disease 
  • Major or Mild Neurocognitive Disorder Due to Another Medical Condition 
  • Major or Mild Neurocognitive Disorder Due to Multiple Etiologies 
  • Unspecified Neurocognitive Disorder

The psychiatric component of the exam determines recommendations for living conditions, while the neurological component of the exam points to the pharmaceutical interventions that are needed to relieve symptoms and sometimes to delay the progression of the disease.

The neuropsychiatrist often orders genetic testing, especially for the ApoE4 gene. Genetic testing can reveal possibility for dietary and lifestyle interventions that make major differences in the progress of the disease. The complete team for someone with "dementia:" usually includes psychologists, social workers, occupational therapists, and nurses to support lifestyle that the patients can no longer manage on their own.

What if you have to make a personal judgment about whether someone for whom you have responsibility has dementia? First of all, don't be overly concerned about occasional memory lapses. Dementia is a chronic condition. Be aware that certain groups of people have a higher likelihood of developing dementia. This includes people who have Parkinson's disease and people who have had strokes. And don't get all of your information from the target of your concern. Family and personal caregivers usually have valuable insights.

  • Iliffe S, Robinson L, Brayne C, et al. Primary care and dementia: 1. diagnosis, screening and disclosure. Int J Geriatr Psychiatry 2009.24:895-901.
  • Prince M, Albanese E, Guerchet M, et al. World Alzheimer report 2014. Dementia and risk reduction: an analysis of protective and modifiable risk factors. Alzheimer’s Disease International, 2014.
  • Robinson L, Tang E, Taylor JP. Dementia: timely diagnosis and early intervention. BMJ. 2015 Jun 16.350:h3029. doi: 10.1136/bmj.h3029. Review. No abstract available. PMID: 26079686.
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