When an older person starts showing signs of cognitive impairment — like confusion, forgetfulness or lack of focus — it’s normal to worry that it could be the beginning stages of dementia or Alzheimer’s disease. Studies show, however, that the concern over a disease like Alzheimer’s is actually more prevalent than the disease itself; the Alzheimer’s Association reports that approximately one in nine people age 65 and older has an Alzheimer’s diagnosis, but a survey conducted by AARP found that nearly half of adults over age 40 think they will develop dementia. 

These statistics might help explain, then, why someone might leap to the conclusion that any cognitive impairment in an older individual could be dementia. However, other treatable conditions can cause similar symptoms, and they can be easy for doctors to miss. It’s important to be aware of these dementia look-alikes in order to avert a possible misdiagnosis. Here are just a few:

A variety of medications
Many prescriptions — and some over-the-counter drugs — can affect cognition. Image by Ca-ssis, via Canva.com

Medication Interactions or Side Effects

If you’ve ever seen a commercial for any medication, you’re probably aware that they can have a ton of side effects. As you age and the number of medications you take increases, the possibility of harmful interactions elevates dramatically. Many prescriptions — and some over-the-counter drugs — can affect cognition, but the most common culprits include those for sleep, urinary incontinence, pain, anxiety and allergies. 

As an added kicker, even prescriptions you’ve been taking for a while without any issues can suddenly start to trigger confusion. As you get older, your kidneys and liver may not filter as well as they used to, so drugs can build up in your system and cause new symptoms.

Normal Pressure Hydrocephalus (NPH)

Normal Pressure Hydrocephalus is a disorder in which cerebrospinal fluid accumulates in the ventricles (cavities) of the brain and interferes with thinking, memory, walking and control of urination. More than 700,000 Americans have this condition, according to the Hydrocephalus Association, which estimates that fewer than 20% are properly diagnosed. A neurologist can diagnose NPH using brain imaging and cerebrospinal fluid tests. The treatment for NPH is usually a shunt (a flexible tube) inserted into the brain to drain the fluid. Typically, once proper treatment is received, the symptoms improve dramatically.


Any untreated infection can cause delirium, or a sudden change in alertness, attention, memory and orientation. Basically, the white blood cells in your body rush to the infection site, which causes a chemical change in the brain that can make older adults feel drowsy, unfocused or confused. Respiratory infections (including COVID-19) and urinary tract infections are common causes of cognitive issues that get misdiagnosed as dementia, particularly because older people can have these infections without the accompanying telltale symptoms.

Vitamin B12 Deficiency

Our bodies cannot produce Vitamin B12 on its own, so we need to consume it from animal products like meat, fish, eggs and milk. Vitamin B12 is necessary in order to maintain a healthy nervous system and manufacture red blood cells. A B12 deficiency is usually caused by a poor or restrictive diet, or by your body’s inability to absorb the nutrient. According to the Cleveland Clinic, people who are 60 years old or older are more likely to have vitamin B12 deficiency than other age groups.

A B12 deficiency can cause physical, neurological and psychological symptoms, which can develop slowly and get worse over time, much like dementia. The general symptoms include fatigue, weakness, nausea, diarrhea, lack of appetite and weight loss. Neurological symptoms can include numbness or tingling in the extremities, vision problems, forgetfulness, confusion and difficulty speaking and walking, depression, irritability and other mood changes. Simple blood tests can usually diagnose B12 deficiency, and treatment, which ranges from taking supplements to getting intravenous B12 injections, can reverse the symptoms as quickly as a week after they’ve started.

Woman sleeping next to alarm clock
Because sleep is essential for our brains to learn, store memories and filter out toxic substances, any interruption in these processes can be highly problematic. Image by Rido, via Canva.com

Sleep Disorders

According to recent studies, insomnia affects 30% to 48% of older people, and regular sleep disruption is an increasingly common complaint. Because sleep is essential for our brains to learn, store memories and filter out toxic substances, any interruption in these processes can be highly problematic. Problems sleeping can lead to confusion, mental fatigue, difficulty focusing and irritability. Menopause can impact the quality of your sleep, as well (for tips on how to get a better night’s rest, check out our article “Tips for Better Sleep, Despite Menopause.”


It might feel like we harp about dehydration a lot here at 55+, but water is such an essential element for keeping our minds and bodies running. Hydration is vital for keeping electrolytes balanced, maintaining blood volume and kidney function, aiding in digestion and transporting nutrients. It also helps with temperature regulation and brain function — so it goes without saying that severe dehydration can easily lead to dementia-like symptoms.

Other Disorders

There are many other conditions, in addition to the ones we’ve listed, that can also cause symptoms that mimic dementia or Alzheimer’s disease. Disorders of the heart, lungs, liver, kidneys or thyroid, as well as sodium deficiency, some cancers, depression and even constipation can lead to confusion, brain fog and forgetfulness. The important thing to take away from these warnings is that if you or a loved one are experiencing cognitive impairment, try not to leap to conclusions. Make sure to ask your medical professional to rule out some of the other possible causes.

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