How is Alzheimer’s diagnosed?

An early and accurate diagnosis of memory or other cognitive difficulties is crucial for several reasons. Foremost, a thorough evaluation can reveal any treatable or even reversible causes of cognitive impairment.  If Mild Cognitive Impairment (MCI), Alzheimer’s disease, or another dementia is diagnosed, it can facilitate planning and permit patients and families to access available medications and services. Also, with early diagnosis, critical safety issues (e.g., living alone, driving) can be addressed before a crisis occurs.

Understanding the diagnostic process

At present, there is no single diagnostic test for detecting mild cognitive impairment (MCI), Alzheimer’s disease, or other forms of dementia. Rather, the diagnosis is based on a thorough assessment by an experienced clinical to determine the presence (i.e., inclusion) and absence (i.e., exclusion) of particular symptoms.  If done thoroughly, such a diagnostic process can yield a highly accurate clinical diagnosis.

Cognitive impairment and dementia can result from a variety of progressive and non-progressive ‘irreversible’ as well as ‘potentially reversible’ causes. For example, potentially reversible causes of cognitive impairment and dementia include severe depression and metabolic disorders (e.g., vitamin B12 deficiency and hypothyroidism) as well as structural brain changes such as occur in Normal Pressure Hydrocephalus (NPH). Medication side effects can cause reversible cognitive difficulties. If a particular drug, or combination of multiple drugs, are causing the cognitive impairments, then stopping the medication(s) and/or changing the dosage may improve symptoms. In some cases, a person may develop cognitive impairment that remains stable and does not progress. A common cause of non-progressive cognitive impairment is a single stroke which permanently impairs certain functions. Another increasingly recognized cause of non-progressive cognitive impairment is traumatic brain injury, as might occur in an auto accident, sports, or combat.

In addition to Alzheimer’s disease, progressive irreversible causes of dementia include ischemic Vascular dementia (VaD) or dementia due to stroke, Dementia with Lewy Bodies (DLB), Fronto-temporal dementia (FTD), Parkinson’s disease dementia (PDD), and several other disorders. As the treatment plan for a person with Alzheimer’s disease will often be quite different from one for an individual with VaD, DLB, FTD, or PDD, it is important for physicians to ascertain the most likely cause of the dementia.

What a comprehensive assessment includes

A comprehensive evaluation of memory or other cognitive problems should include:

  • A complete clinical history that includes questions about the individual’s overall health, current and past medical conditions, prescription and over-the-counter medications, risk factors (e.g., head trauma, excessive alcohol use), ability to perform daily activities, and changes in behavior and personality.
  • Physical and neurological examinations to, for example, look for changes such as slowed movement, weakness, or other symptoms linked to neurological disorders such as Parkinson’s disease or stroke.
  • Neuroimaging to look for structural (e.g., CT, MRI), metabolic (e.g., SPECT, FDG, PET), or disease-related (amyloid PET) changes.
  • Laboratory tests of blood and urine to check for possible contributors to any cognitive difficulties, such as a B12 deficiency.
  • Neuropsychological assessment measures performance on paper-and-pencil tests assessing orientation to time and place, recent memory, language, attention, visual-spatial abilities, and executive functioning (e.g., reasoning, problem-solving, insight, multi-tasking, and planning).

Probable, possible, and definite Alzheimer’s disease

A definite diagnosis of Alzheimer’s disease can still only be given upon death, following an autopsy of the brain in which a neuropathologist looks for hallmark senile plaques and neurofibrillary tangles in the brain.  During life, a doctor may use the terms “probable” and “possible” to indicate the level of diagnostic certainty.  A diagnosis of “probable AD” means the doctor has ruled out all other possible sources of the cognitive impairment, leaving Alzheimer’s disease as the most likely cause.  When the cognitive impairment is believed to be due to Alzheimer’s disease but another condition (e.g., vascular disease) exists that could be contributing to the dementia, a doctor may give the diagnosis of “possible Alzheimer’s disease.”

Some individuals may have more memory or cognitive difficulties than is typical for people their age, but continue to be able to manage their day-to-day activities.  In this case, the doctor may diagnose Mild Cognitive Impairment (MCI), a high-risk pre-dementia state.

UCI Memory Assessment and Research Center

At the UCI MIND Memory Assessment and Research Center, the diagnostic evaluation is performed across two visits on separate days, usually within the same week. During the first visit, which lasts about three hours, the individual with memory or other cognitive problems is administered a comprehensive battery of neuropsychological tests.  The purpose of this testing is to evaluate the individual’s performance on paper-and-pencil tests assessing orientation to time and place, recent memory, language, attention, visual-spatial abilities, and executive functioning (e.g., reasoning, problem-solving, insight, multi-tasking, and planning). While the patient is undergoing the testing, a thorough medical history is being gathered by a clinician from someone who knows the individual well (e.g., spouse, adult child, or close friend). Blood tests for thyroid function, vitamin B12, and folate are usually drawn to help rule out potentially reversible causes and to identify any infectious diseases (e.g., encephalitis). Physical and neurological examinations are performed by the clinic neurologist during second visit, which usually lasts one hour.  During this visit, the neurologist may order additional brain imaging studies (i.e., CT, MRI, or SPECT). Although certain findings on these scans may help support a diagnosis of Alzheimer’s disease or another dementia, their primary purpose is to rule out other possible explanations, such as tumors, strokes, and head trauma. Once all tests are completed, the clinical team reviews the results to determine the diagnosis and develop an individualized treatment plan for the patient.  Results of the tests, the diagnosis, and the treatment plan are presented to the patient and family during a family conference.  Families benefit from the opportunity to ask questions about the diagnosis, treatment, and community resources (e.g., adult day services).  Finally, if eligible and interested, the patient may be invited to join the UCI MIND Longitudinal Study or other research studies.

Contacting the UCI MIND Memory Assessment and Research Center

  • For memory assessments: Please call (949) 824-2382, Option 2, to speak to a Patient Care Coordinator.
  • To learn about participating in research: Please call (949) 824-2382, Option 3, to speak to the UCI MIND Research Coordinator.