In general, symptoms of Alzheimer’s disease and other types of dementia get worse with time. Still, it’s common for symptoms to vary from day to day. In particular, agitation and other behavior changes may seem stronger at certain times. Sometimes, another medical condition, such as delirium, can appear suddenly, causing dementia symptoms like confusion to worsen quickly.

Here, we’ll explain how dementia progresses and why symptoms can fluctuate.

How Dementia Progresses

Dementia is a neurodegenerative disease. This means it causes damage to the brain and nervous system. These conditions usually start slowly and get worse over time.

In dementia, brain cells called neurons are destroyed. Neurons are the cells involved in cognitive function — they allow you to think, remember, learn new information, and organize. In Alzheimer’s disease, neuron death is caused by the buildup of two proteins — amyloid and tau. These “amyloid plaques” and “tau tangles” build up in the brain and damage neurons, which causes dementia symptoms.

How Alzheimer’s Progresses

Alzheimer’s disease tends to worsen over time. At first, only neurons in one part of the brain are affected. Over time, the buildup of proteins spreads and affects neurons in other areas. The hippocampus — the part of the brain in charge of memory — is often impacted first. This is why issues with short-term and long-term memory are so often symptoms of Alzheimer’s disease.

How Other Dementias Progress

Like Alzheimer’s disease, most other types of dementia also worsen over time. In frontotemporal dementia, neurons in the front and side (temporal) parts of the brain are damaged, leading to gradual changes. In Lewy body dementia, protein buildups called Lewy bodies form in the brain and cause cognitive impairment (thinking problems) that worsens over time.

Vascular dementia is caused by a low blood supply in the brain. This type of dementia can be caused by a stroke or other medical conditions that restrict blood flow, such as diabetes and atherosclerosis.

Vascular dementia can get worse in different ways. For some people, it worsens slowly over time, like Alzheimer’s disease. For others, symptoms may suddenly get much worse at once — like after a stroke. When a stroke leads to a major loss of cognitive function, symptoms may stay the same for a while and then get worse again if another stroke happens, in a steplike progression.

What Symptoms Can Come and Go

After the early stages of dementia, behavioral symptoms often start to appear. During this stage, a person may act differently from day to day. This can make it harder for caregivers, especially when loved ones show unpredictable or difficult behaviors.

Behaviors that may come and go include:

• Yelling or other acts of aggression
• An inability to sit still, such as fidgeting or pacing
• Trouble falling or staying asleep
• Doing something over and over again, such as repeating the same question or phrase
• Saying or doing things that aren’t appropriate for the situation, such as trying to remove clothing in public
• Following a caregiver closely or wanting to stay near them at all times

People living with dementia may act this way when they have unmet needs. Feelings like hunger, boredom, or loneliness can show up as these behaviors when your loved one can’t identify and express them to you. As those needs change, you may notice their symptoms change, too.

Why Symptoms May Worsen Suddenly

Although dementia usually worsens gradually over time, symptoms can sometimes get much worse all of a sudden. Depending on the reason, it may be possible to reduce confusion and other symptoms by treating their underlying cause.

Delirium

If you notice a sudden change in your loved one’s symptoms, it may be due to delirium. Though symptoms often differ by person, delirium almost always makes a person seem suddenly confused, distant, or unresponsive. These changes usually appear quickly, over a period of one or two days. If you notice any sudden, unexplained changes in your loved one’s behavior, get in touch with their healthcare provider as soon as possible.

Delirium and dementia can have some of the same symptoms. This can make it harder for a healthcare provider to diagnose the condition. Doctors often rely on family members to help determine whether a person’s behavior is unusual or out of character for them.

So, what does delirium look like? There are many possible symptoms of delirium. People experiencing delirium can have symptoms that change as often as every hour. Common symptoms of delirium include:

• Being unresponsive to their environment
• Feeling confused or disoriented
• Having trouble speaking or keeping up with the conversation
• Losing normal abilities all of a sudden — For example, suddenly being unable to walk
• Getting distracted more easily than usual
• Experiencing sudden mood swings
• Having delusions or paranoia — Believing that things are true despite evidence they aren’t
• Having hallucinations — Hearing or seeing things that aren’t there

Older adults over 65, especially those with dementia, have a higher risk of developing delirium. It often happens as a reaction to another condition that affects how the brain works. Common causes of delirium include:

• Infections, such as urinary tract infections (UTIs)
• Undergoing major surgery with general anesthesia
• Pain or injury, such as head trauma
• Medication side effects
• Not drinking enough water or not getting enough nutrients
• Not being able to pee or poop
• Low oxygen levels in the blood or organ failure

Once the cause of delirium is identified and treated, symptoms often get better within several days. In some cases, memory issues or cognitive problems may linger for weeks or months. Older people who develop delirium after surgery may be more likely to have symptoms that last longer.

Sundowning

It’s common for dementia symptoms to worsen as the day winds down. Sundowning refers to increased confusion, irritability, or aggression that happens around the early evening. Someone who is sundowning may appear very upset and may even see or hear things that aren’t there. If your loved one is sundowning, you’ll see that their symptoms come and go depending on the time of day.

Doctors don’t know exactly why sundowning happens in people with dementia. Possible causes may include unmet needs — such as hunger, pain, or sensory discomfort — and changes to the body’s internal clock.

If you think your loved one is sundowning, try to figure out the cause of their behavior. Some things to consider include:

• Do they need to eat or use the bathroom?
• Could they be in pain?
• Are lighting sources creating shadows or reflections that might look confusing or scary? Try closing blinds and covering mirrors or TVs (when not in use) to see if this helps.
• Could a recent event from earlier in the day be upsetting them? If so, gentle distraction may help.

Join the Conversation

On myALZteam, people share their experiences with Alzheimer’s disease, get advice, and find support from others who understand.

Have you noticed that your loved one’s dementia symptoms fluctuate? Let others know in the comments below.