Is memory loss always Alzheimer's?

No. Many causes of memory loss are treatable and some are fully reversible, including vitamin B12 deficiency, thyroid disorders, sleep apnea, depression, and medication side effects. An evaluation sorts through the possibilities before anyone settles on a diagnosis.

Can memory loss be reversed?

It depends on the cause. Memory loss from vitamin deficiencies, thyroid problems, sleep apnea, medications, or depression can often be reversed with treatment. Neurodegenerative conditions such as Alzheimer's disease can be managed but not cured, and earlier evaluation gives you more options.

Can short-term memory loss be reversed?

Often. Short-term memory is the first thing to suffer from poor sleep, depression, sedating medications, and thyroid or vitamin problems, and it recovers when those are treated. When short-term memory loss is slowly progressive over years and noticed by family, the cause needs a proper evaluation, because that pattern can be the early stage of a neurodegenerative disease.

Is memory loss permanent?

Not usually. Most of the common causes are reversible or improve with treatment. Memory loss from a stroke or a head injury often improves partly over months. Memory loss from a neurodegenerative disease is lasting, but it can be slowed and planned for, and finding it early gives you the most options.

What is it called when you cannot form new memories?

Anterograde amnesia. Losing memories from before an event is retrograde amnesia. Either one appearing suddenly, after a head injury, a seizure, or an illness, needs prompt medical evaluation.

What tests diagnose memory loss?

Evaluation starts with a detailed history, a neurological examination, cognitive screening, and blood tests for reversible causes such as vitamin deficiencies and thyroid problems. Brain imaging and formal neuropsychological testing are added when they will change the diagnosis or the plan.

When should I see a neurologist for memory loss?

See a neurologist if memory problems interfere with daily tasks or work, if you forget important events repeatedly, if you get lost in familiar places, or if family members have expressed concern about your memory.

Memory Loss: Neurologist Guide to Causes, Tests & Treatment

Memory Loss: Causes, Symptoms, and When to See a Neurologist

Memory loss has many causes, and a good number of them are treatable: vitamin B12 deficiency, thyroid disease, sleep apnea, depression, and medication side effects among them. See a neurologist when memory problems interfere with daily life, repeat themselves, or worry the people around you. Evaluation starts with a 60-minute visit and cognitive screening, then blood tests, imaging, or formal testing when they will change the answer.

Medically reviewed by Dr. Achillefs Ntranos, MDPublished September 11, 2024Updated September 3, 20269 min read

A whole brain rendered in soft copper and slate-blue watercolor.

Memory loss is one of the most common cognitive symptoms that brings people to a neurologist, and one of the most frightening. Most people who come in worried about their memory do not have dementia, and many have something treatable. This page covers what separates normal forgetting from the kind worth investigating, and how the cause is found.

What memory loss is

Memory loss is difficulty forming, storing, or retrieving memories. It can affect recent memory, long-term memory, or both, and it can be temporary or lasting. Some slowing of recall is normal with age: the information is there and it takes longer to surface.

What is not normal is memory that is progressively worse, or that interferes with things you used to manage without thinking. That deserves an evaluation, and not because the news is likely to be bad. It is because so many of the causes can be corrected.

Short-term and long-term memory loss

People search for these as if they were two different diseases. In practice the distinction is a clue to the cause. Short-term memory loss, where new information does not stick and you repeat questions or lose track of the week, is the pattern of sleep deprivation, depression, medications, and, when it is progressive over years, the early stage of Alzheimer's disease. Long-term memory loss, where established knowledge or old events fall away, is uncommon on its own and points elsewhere: a head injury, a stroke, encephalitis, heavy alcohol use, or a later stage of a neurodegenerative disease.

The inability to form new memories has a name, anterograde amnesia; losing memories from before an event is retrograde amnesia. Both are unusual outside injury, seizure, or illness, and both call for prompt evaluation.

Normal aging or something more

Situation	Usually normal aging	Worth evaluating
Names	Losing a name and recovering it later	Not recognizing people you know well
Losing things	Misplacing keys or a phone	Finding items in odd places, such as keys in the freezer
Conversations	Forgetting part of a conversation	Repeating the same question within an hour
Getting around	Pausing to think about directions	Getting lost on a familiar route
Everyday tasks	Needing a list for a complicated week	Struggling with a recipe or the bills you always handled
Words	Occasionally hunting for a word	Substituting wrong words often enough that others notice
Who notices	You notice, others do not	Family notice before you do, or disagree that anything is wrong

The right-hand column is not a diagnosis. It is the threshold at which the cause is worth finding, and mood changes or lost interest in things you enjoyed belong there too.

Sudden memory loss or confusion is an emergency

Memory loss or confusion that starts suddenly, especially with weakness, trouble speaking, a severe headache, or a fall, can be a stroke or another acute problem. Call 911 or go to the nearest emergency department. The gradual memory changes described on this page are evaluated in the office.

What causes memory problems

The list of what causes memory loss and forgetfulness is long, but in clinic a short list accounts for most of it. The rows are ordered roughly by how often we find them.

Cause	What points to it	Reversible
Medications	Sedatives, sleep aids, some bladder and allergy medications, opioids. Symptoms that track a new prescription	Usually
Sleep apnea and sleep disorders	Snoring, waking unrefreshed, daytime sleepiness	Usually
Vitamin B12 deficiency, thyroid disease	Found on blood tests, often with fatigue or other body symptoms	Usually
Depression, anxiety, sustained stress	Attention is the problem, and what is not attended to is not stored. Can closely mimic early dementia	Usually
Heavy alcohol use	A long history of heavy drinking, sometimes with poor nutrition	Partly
Concussion or head injury	Onset dates to the injury	Often improves
Stroke, including small silent ones	A step change rather than a slow slide, or an abnormal MRI	Managed, not reversed
Neurodegenerative disease	Slow progression over years, recent memory affected first, noticed by family	Managed, not reversed

Neurodegenerative disease is what people fear when they book, and it is last on this list for a reason. The rows above it are more common and more fixable, so they get checked first.

Brain illustration beside a notebook, glasses, pillow, and blood sample tube. — Memory problems are evaluated in the context of everyday function and possible causes.

How the cause is found

A detailed history, ideally with a family member present, because the person with the memory problem is often the least able to describe it.
A neurological examination and cognitive screening during the visit.
Blood tests for vitamin deficiencies, thyroid function, and other medical contributors.
A medication review, every prescription and over-the-counter product. One of the highest-yield parts of the evaluation.
Brain imaging, usually MRI, when the history or examination calls for it.
Neuropsychological testing when a detailed map of which abilities are affected would change the plan.

Treatment

Treat the cause. Replacing vitamin B12, correcting thyroid function, treating sleep apnea or depression, or stopping an offending medication often improves memory, sometimes markedly.
Medication for neurodegenerative disease. Symptomatic treatments help many patients, and for some with early disease newer treatments aim to slow progression. We discuss honestly whether you are a candidate and where they are given.
Memory aids and routine. Calendars, phone reminders, pill organizers, and a consistent daily structure help more than most people expect.
The habits that protect the brain. Exercise, a Mediterranean-style diet, sleep, social contact, and control of blood pressure, cholesterol, and blood sugar. Our article on keeping your brain healthy covers these.

What an evaluation here involves

A memory evaluation starts with a 60-minute visit with Dr. Achillefs Ntranos, MD, a board-certified neurologist who trained at Mount Sinai and completed postdoctoral neuroimmunology research at Johns Hopkins. Bring your medication list, prior imaging or test reports, and, if you can, someone who knows you well. MRI images can be uploaded ahead through our patient tools page. We look for the less obvious contributors as well as the usual ones, including neuroinflammation, autoimmune conditions, and sleep disorders.

Formal neuropsychological testing is not done in our office; we arrange it and review the report with you and your family, with a written plan. We see patients in Beverly Hills and West Los Angeles and by video anywhere in California, and you can book a visit without a referral. If the DMV has asked for a medical evaluation, we also perform DMV driver evaluations.

Notebooks, glasses, cognitive sorting blocks, and a blood sample tube. — The evaluation combines everyday observations with examination and selected tests.