Dementia, the general term for loss of memory, language, and other thinking abilities that interfere with daily life, is most commonly in the form of Alzheimer’s disease. But other types are Lewy body dementia (which Robin Williams had been diagnosed with before his death by suicide), Parkinson’s dementia, vascular dementia and frontotemporal dementia—the condition affecting both Bruce Willis and Wendy Williams.

The estimate of how many people will develop dementia in their lifetimes is now higher than ever—42% for both men and women, according to a new study—with about 1 in 9 Americans 65 and older currently dealing with dementia, according to the Centers of Disease Control and Prevention, and 55 million people affected worldwide. 

Below are some early dementia signs—many unexpected—to watch out for.

1. Vision changes

Trouble with visual images and spatial relationships, including vision changes that could lead to issues with balance or reading and difficulty judging distance or seeing color contrasts, can affect some people living with dementia, according to the Alzheimer’s Association. 

2. Nightmares

A large 2022 cohort study found that middle-aged adults who had bad dreams at least once a week were four times more likely to experience cognitive decline in the coming decade. It also found that older adults plagued by nightmares were twice as likely to be diagnosed with dementia than peers who never had bad dreams.

Such bad dreams may “identify people who are at high risk of developing dementia in the future, several years or decades before the characteristic memory and thinking problems emerge,” neuroscience researcher and study lead Abidemi Otaiku told Medscape Medical News.

“This would be the optimum time for doctors to intervene to try and slow down or prevent dementia from developing.”

Acting out dreams and suddenly talking in one’s sleep could be another sign, according to older research.

3. Diminished sense of smell

Loss of olfactory function is also an early symptom of neurodegenerative diseases including Parkinson’s and Alzheimer’s, according to recent findings published in Neurology. It found that the link between sense of smell and cognitive changes may be especially pronounced among those who develop cognitive impairment or dementia, 

4. Changes in behavior including apathy or increased anxiety

Apathy, according to a 2023 study published in the Journal of Alzheimer’s Disease, could be a sign that someone is progressing from mild cognitive impairment (MCI) (less severe than dementia) to Alzheimer’s disease.  

Acting increasingly anxious, confused, fearful, irritable, or suspicious, meanwhile, may also be a sign of dementia, according to the Alzheimer’s Association—as can a person’s withdrawal from social activities, due to difficulty following and taking part in conversations.

5. Disruptive memory loss, including word loss

One of the most common early signs of dementia is short-term memory loss—as is forgetting important dates or events, repeating questions over and over, and an increasing need to rely on reminder notes, phone alerts, or family members for things previously handled independently, notes the Alzheimer’s Association.

In addition, language problems such as not being able to find the right word, using the wrong word as a substitute, or jumbling the order of words may be a sign, particularly of frontotemporal dementia. 

6. Trouble multitasking or completing familiar tasks

Experiencing changes in one’s ability to develop and follow a plan, work with numbers, follow a familiar recipe, or keep track of monthly bills are all signs to pay attention to—as is having difficulty concentrating or taking much longer to do things than before.

Another sign is that it’s suddenly hard to complete daily tasks, such as driving to a familiar location, organizing a grocery list, or remembering the rules of a favorite game, notes the Alzheimer’s Association.

7. Poor judgment

A change in judgment or decision-making skills is another early sign—using poor financial judgment, for example, letting their grooming fall by the wayside.

Further, according to the findings of a recent study, being vulnerable to financial scams could be an early indicator of Alzheimer’s disease. 

8. Depression

A sudden onset of depression later in life can also be a warning sign of dementia, according to the Alzheimer’s Association, which notes that up to 40 percent of people with Alzheimer’s disease suffer from significant depression.

Depression may also be a precursor to dementia, according to a 2023 study published in JAMA Neurology, which found that dementia risk more than doubled for adults previously diagnosed with depression. “While depression diagnosed later in life is generally thought to be an early symptom of dementia, our results suggest that a depression diagnosis at any point in adulthood increases the risk of dementia later on,” lead author, Holly Elser, a neurology resident at Penn Medicine, said in a press release about the study.

More on dementia:

• 5 ways to reduce your dementia risk as study estimates U.S. cases could double by 2060
• Dementia risk is soaring as Americans live longer. 4 steps can help reduce your risk
• This vitamin deficiency can cause forgetfulness and mimic symptoms of dementia—but it’s reversible. Doctors explain the signs to look for
• Belly fat tied to brain health in middle-aged adults at high risk of Alzheimer’s, study finds—but it’s worse for men