Diagnosing dementia

Dementia Diagnosis & Diagnostic Testing January 19, 2017

Alzheimer's Association diagnostic guidelines across the disease continuum

Essentials of a diagnostic workup

clinical exam
medical history
assessment of multiple cognitive domains
lab tests
MRI and/or CT scan, in some cases

The original diagnostic criteria for the diagnosis of Alzheimer's disease were developed in 1984. The Alzheimer's Association and the National Institute on Aging (NIA) recently updated and added to those guidelines.

Role of advanced imaging and biomarkers

As disease-modifying therapies become available, initiating therapy early in the disease, before clinical signs emerge, will be critical, so research on new strategies for earlier diagnosis is among the most active areas in Alzheimer's science. Although there are no validated biomarkers for Alzheimer's disease, researchers are investigating genetic risk profiling, cerebrospinal fluid biomarkers, such as beta-amyloid and tau, and advanced brain imaging techniques that will allow clinicians to detect and monitor genetic, metabolic, vascular and cellular changes related to Alzheimer's disease.

Differential diagnosis

Alzheimer's disease accounts for up to 80 percent of all dementia cases. Diagnosis may be complicated by other forms of dementia that have symptoms and pathologies similar to Alzheimer's disease. Knowing the key features and pathology of each type of dementia can help in the accurate diagnosis of patients, so they will receive the treatment and support services appropriate for their condition and maintain the highest possible quality of life.

The following table identifies some of the clinical differences between the major dementias

Clinical Differentiation of the Major Dementias

Disease	First Symptom	Mental Status	Neuropsy- chiatry	Neurology	Imaging
AD	Memory loss	Episodic memory loss	Initially normal	Entorhinal cortex and hippocampal atrophy
FTD	Apathy; poor judgment/ insight, speech/ language; hyperorality	Frontal/ executive, language; spares drawing	Apathy, disinhibition, hyperorality, euphoria, depression	May have vertical gaze palsy, axial rigidity, dystonia, alien hand, or MND	Frontal, insular, and/or temporal atrophy; spares posterior parietal lobe
DLB	Visual hallucinations, REM sleep disorder, delirium, Capgras' syndrome, parkinsonism	Drawing and frontal/ executive; spares memory; delirium prone	Visual hallucinations, depression, sleep disorder, delusions	Parkinsonism	Posterior parietal atrophy; hippocampi larger than in AD
CJD	Dementia, mood, anxiety, movement disorders	Variable, frontal/ executive, focal cortical, memory	Depression, anxiety	Myoclonus, rigidity, parkinsonism	Cortical ribboning and basal ganglia or thalamus hyperintensity on diffusion/ FLAIR MRI
Vascular	Often but not always sudden; variable; apathy, falls, focal weakness	Frontal/ executive, cognitive slowing; can spare memory	Apathy, delusions, anxiety	Usually motor slowing, spasticity; can be normal	Cortical and/or subcortical infarctions, confluent white matter disease

Abbreviations: AD, Alzheimer's disease; CBD, cortical basal degeneration; CJD, Creutzfeldt-Jakob disease; DLB, dementia with Lewy bodies; FTD, frontotemporal dementia; MND, motor neuron disease; PSP, progressive supranuclear palsy

Reproduced with permission. Seeley WW, Miller BL. Alzheimer's disease and other dementias. In: Harrison's Neurology in Clinical Medicine. 3rd edition. ©The McGraw-Hill Companies, Inc.

Healthcare Professional Topic Sheets

Healthcare professional topic sheets are available for the following dementias and dementia-like conditions:

Disclosure of an Alzheimer's disease diagnosis

Almost 90 percent of Americans say if they were exhibiting confusion and memory loss, they would want to know if the cause of the symptoms was Alzheimer's disease. Disclosure and discussion of a diagnosis of Alzheimer's disease or other dementia is an ongoing process that should be addressed during multiple office visits. You can refer patients and their families to the Alzheimer's Association to learn about Alzheimer's disease, find a support group, get advice about caregiving or participate in a clinical trial.

Instructional videos

The following videos show the disclosure of an Alzheimer's disease diagnosis and a peer-to-peer discussion of important aspects of assessing cognition and disclosing an Alzheimer's disease diagnosis during a primary care visit. The videos, part of a three-part instructional series developed for primary care providers, use an actual primary care physician and patient with Alzheimer's disease.

Disclosing an Alzheimer's Diagnosis (approx. 11 min)

Peer-to-peer discussion of important aspects of assessing cognition and disclosing Alzheimer's disease during primary care visits (approx. 11 min.)

Videos produced by the American College of Physicians Foundation and the Alzheimer's Association.

References

1. Seeley WW, Miller BL. Alzheimer's disease and other dementias. In: Hauser SL, ed. Harrison's Neurology in Clinical Medicine. 3rd edition. New York: McGraw-Hill Medical; 2013.

2. Harvard School of Public Health, Alzheimer's Europe. Value of knowing - Research - Alzheimer Europe. Value of Knowing. Available at: . Accessed October 13, 2011.