What Dementia Is, and Isn’t

Several diseases can cause dementia, a decline in memory, thinking or other abilities that affects everyday life. It isn’t a normal part of growing older.

Deep inside each side of the brain sits the hippocampus, the memory center. It saves new moments so they can be found again later. In Alzheimer’s, it’s often where the damage starts.

So new things slip first: a phone call this morning, a question she just asked. Memories laid down long ago tend to last longer. She may tell you about her wedding day but not about breakfast, and look for things where they’ve always been.

What helps

• Tell, don’t quiz. “Ann called this morning” is easier than “Guess who called?”
• Write it down. A note or a board she can read again does the remembering for her.
• Keep things where they’ve always been, since old maps outlast new ones.
• If she asks again, answer again, kindly, as if it’s the first time. For her, it is.

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Light enters the eyes, but seeing happens at the back of the brain, which turns the signal into a picture. Even when the eyes are healthy, dementia can make that picture harder to read.

Judging color, contrast and distance can get harder. A white plate on a white cloth can seem to disappear, and a dark mat can look like a hole. In a rarer form called posterior cortical atrophy, eye tests can come back normal while the back of the brain is affected. Some studies have estimated about 5%, but its true prevalence is uncertain.

What helps

• Rule out the eyes first: glasses on, clean and the right pair, and regular eye tests.
• Make things stand out: a bold plate under pale food, on a plain cloth.
• Good light, fewer things. Shadows and clutter leave more to misread.
• Say what’s there: “Chicken and potatoes, on your red plate.”

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Sound travels from the ears to the side of the brain, where speech is sorted into words and meaning. With dementia, that sorting can take longer, and several sounds at once compete: the TV, a second voice, the kettle.

Hearing itself matters too. Of 14 risk factors for dementia across a lifetime, hearing loss is one of the two largest, linked to about 7% of cases. In the ACHIEVE trial of 977 adults aged 70 to 84 with hearing loss, hearing care made little difference to thinking overall. But in those at higher risk, it slowed the decline by 48% over three years.

What helps

• Get hearing checked, and keep hearing aids in, clean and working.
• Turn off the TV before you talk, and face her as you speak.
• One voice, one idea at a time, then give her time to answer.

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Each step starts as a signal at the top of the brain. It travels down the spinal cord to the legs, while the cerebellum, at the back, keeps posture and balance steady. Dementia can slow these signals: shorter steps, a wobble, a trip.

Older adults with dementia have twice the risk of falling, and three times the risk of a serious fall injury. In some types walking changes early, like a shuffling walk in Lewy body dementia, or trouble with walking and balance in vascular dementia.

What helps

• Keep walking every day, together if that helps her feel steady.
• Clear the path: loose rugs gone, cords away, good light, and a night light on the way to the bathroom.
• Sturdy shoes that fit well and grip.
• Tell the doctor about new walking problems. Some causes, like normal pressure hydrocephalus, can be treated.

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The brain is hungry. With each heartbeat, about 20 to 25% of the body’s blood goes to the brain, carrying fuel and oxygen. In vascular dementia, reduced blood flow damages brain cells and, over time, kills them.

Food and drink matter in two different ways:

So far, healthy habits together have shown a benefit in a trial, while a special diet on its own hasn’t. Be wary of any food or supplement sold as a dementia cure.

What helps

• Offer drinks through the day, in a cup she likes and can see, rather than waiting for her to ask.
• Regular meals, on plates that stand out from the food and the table.
• Checkups for blood pressure and blood sugar, to protect the vessels that feed the brain.

The person is still there, and still feels. Dementia can make feelings harder to explain and to manage, but it doesn’t switch them off.

Feelings outlast facts. In one study, people with Alzheimer’s watched sad or happy film clips. They soon forgot much of what they had seen, but the sadness or happiness lasted for up to 30 minutes. A sharp word can leave hurt behind after the words are gone, and a kind one can leave warmth.

Behavior is often a message. When something is wrong, she may not be able to say what. Restlessness, upset or saying no can be about pain, thirst, the toilet, noise, boredom or worry. Low mood is common too: depression can occur alongside dementia. A clinician can assess symptoms and discuss treatment.

What helps

• Look for the need behind it: pain, thirst, the toilet, noise, boredom.
• Keep good moments in the day: a steady routine, things she enjoys, and small successes noticed.
• Talk with her, not about her, even when others are in the room.
• Tell the doctor about low mood, constant worry or a sudden change.

Fixable First

Some things make thinking, seeing, hearing or walking worse, and they can be checked or treated. Tick what’s been checked, add notes, and take it to the next doctor’s visit. It’s kept only while this page stays open.