Alzheimer's disease is diagnosed clinically, by establishing a pattern of progressive cognitive decline, confirming it affects daily function, and excluding other explanations. Testing supports that judgement rather than replacing it, and no single test provides the answer on its own.
Alzheimer's disease is diagnosed clinically, by establishing a pattern of progressive cognitive decline, confirming it affects daily function, and excluding other explanations. Testing supports that judgement rather than replacing it, and no single test provides the answer on its own.
The core requirements are cognitive decline that is progressive rather than static, that represents a change from how someone previously functioned, and that interferes with independence in daily activities. That last point separates dementia from mild cognitive impairment, where testing is abnormal but function is preserved. Establishing the pattern requires a history from someone who knows the person well, because those living with the changes commonly adapt around them without registering the extent.
A diagnosis is only as good as the alternatives ruled out. Thyroid disease, vitamin B12 deficiency, metabolic abnormalities, sleep apnoea, depression, alcohol and medication effects can all produce similar pictures, and several improve with treatment. Other dementias must also be distinguished, since vascular cognitive impairment, Lewy body dementia and frontotemporal dementia present differently and are managed differently. The order in which symptoms appeared is often the most useful clue.
Clinicians talk about probable rather than definite Alzheimer's disease during life, and that is not hedging: it reflects a genuine limit. Biomarkers have improved confidence considerably, but a diagnosis remains a judgement built from history, examination, cognitive testing, imaging and exclusion. Asking what the diagnosis rests on and what would change it is a reasonable question and usually produces a more useful conversation than asking whether it is certain. One more thing worth asking about is timing. An assessment is often more informative when repeated after six to twelve months, because progression over time is itself diagnostic in a way a single snapshot cannot be. If the first assessment is inconclusive, that is a reason to arrange a review rather than a reason to conclude nothing is wrong.
Clinical Neurology Specialists has been physician-owned since 1998, when Leo Germin, M.D., FAANEM founded it. Five board-certified neurologists and four advanced practice providers see patients at the Las Vegas and Henderson offices, each with its own AANEM-accredited electrodiagnostic laboratory.
Clinical Neurology Specialists is an adult outpatient neurology practice for patients 18 and older. The practice performs no surgery and operates no imaging suite, infusion suite or interventional pain programme, and provides no emergency or inpatient care.
Physician-reviewed. Reviewed by the physicians of Clinical Neurology Specialists — board-certified neurologists, AANEM-accredited electrodiagnostic laboratories, physician-owned since 1998. Reviewed 1 August 2026. This article is general education for adults 18 and older and is not a substitute for a consultation.
Sources and further reading: MedlinePlus: Alzheimer disease; National Institute on Aging; MedlinePlus: memory.
Adults 18 and older, at the Las Vegas and Henderson offices. Call 702-804-1212 or request an appointment online.