How dementia impacts behavior

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In the initial stages, family and friends often don’t realize how much dementia affects someone. They may see that the person with dementia seems confused or is slower at normal tasks. But they don’t think these changes could be related to dementia. They may even get irritated or sad because they think the person is stubborn or lazy. This reaction makes the persons with dementia feel worse and affects their behavior. The person’s physical surroundings may not be suitable, which adds to their problems.

Persons with dementia have reduced cognitive abilities. This may affect their memory. It affects their ability to do things. It may affect their emotions and reactions. This page discusses how dementia may affect a person’s behavior. The discussion is not “exhaustive”, but may help caregivers think about what types of changes may happen and how to help the person. They can then also think of home changes that would reduce the difficulties that the persons face and that will keep the persons more independent and safe. They can reduce the possibility of persons with dementia harming themselves and others because of “changed behavior.”

Sections on this page:

The brain gets damaged in dementia

Brain side cropped: image from National Institute on Aging/National Institutes of Health

You can appreciate that dementia affects behavior if you realize that dementia causes physical changes in the brain.

The brain is a very complex organ with billions of cells (neurons) that communicate with each other. Different parts of the brain perform different tasks. Dementia-causing diseases create physical changes in the brain.
Dementia-causing diseases affect the brain. Which part of the brain gets damaged by dementia, and how this damage increases over time depends on which disease is causing the dementia. Image courtesy for image on left: National Institute on Aging/National Institutes of Health.

The damage to the brain increases as dementia progresses. The damage may become more severe, and more areas of the brain may also get damaged.

The image panel below shows the brain changes that happen in Alzheimer’s Disease, the leading cause of dementia. These images show how the damage gets worse over time. (Image courtesy for images below: National Institute on Aging/National Institutes of Health).

Images showing Pre-clinical Alzheimer’s Disease, Mild Alzheimer’s Disease and Severe Alzheimer’s Disease.

preclinical alzheimer brain: image from ADEARBrain of mild Alzheimers : image from National Institute on Aging/National Institutes of HealthSevere Alzheimers brain: image from National Institute on Aging/National Institutes of Health

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How dementia affects the ability to do things and may cause unusual behavior



Impact on behavior

Brain side cropped: image from National Institute on Aging/National Institutes of Health


Image courtesy: National Institute on Aging/National Institutes of Health.

There are many diseases that can cause dementia.


Different diseases damage the brain in different ways. Also, the effect of a disease on the brain is different in different people.

Problems faced by persons with dementia are different from person to person.


For example, some may have more problems walking, while others may have more problems while speaking.

Contrast healthy brain with severe Alzheimers: image from ADEAR


Image courtesy: National Institute on Aging/National Institutes of Health

As dementia progresses, the damage to the brain increases. More areas of the brain may get damaged.Visible symptoms increase depending on the areas of the brain affected, and the severity of the damage. As more and more parts of the brain are harmed, the person’s ability to perform activities of daily living keeps decreasing. Communication may become more difficult. Memory loss is common in many types of dementia. Major personality changes are seen in some types of dementia. There is an overall deterioration.


In the final stages, the person with dementia is fully dependent. The person is often unable to communicate.

dementia reduces ability to planEvery task has several steps. Inability to do one or more of these steps means the task cannot be done properly.If the dementia-causing disease has affected the person’s ability to do some of the steps of a task, the person will not be able to do that task alone and will need help.
dementia patients are confused and have poor coordinationEvery task requires coordination of various parts of the body and the ability to pay attention. Many parts of the brain have to function properly to perform this.


For example, consider lighting a gas stove. For this the lighter has to be put near the burner. The lighter button has to be clicked just when the correct gas stove knob is turned on.

As dementia gets worse, some parts of the brain required for such coordination and focus are likely to get damaged.

The persons will no longer be able to do complex tasks that need precision and coordination. When they try to do such tasks, they may get frustrated or have an accident.
dementia patients mood swings affect their abilities drasticallyEveryone has some fluctuation in their abilities over days, depending on their mood and health and energy.


Persons with dementia often show ups and downs in their ability to do a specific task or remember something. Fluctuations in cognitive ability are particularly common in Lewy Body Dementia.

Friends and family may find it odd that the person with dementia can remember something on one day but not remember it later. Or when they see the person do a task one day and not on the next day. They may think the person is being lazy or stubborn. It is useful to know that such fluctuations may be common in their form of dementia.
dementia wandering casePersons with dementia may get disoriented because of many cognitive problems. Examples of such problems: loss of memories, visio-spatial problems, feeling uncomfortable because of too much light or noise, inability to recognize common objects around them, etc.This leads to many problems, such as
  • The person may wander and forget the way back home.
  • The person may think he/ she is younger and not recognize the children and grandchildren, or may mistake the daughter for the wife.
  • The person may even not recognize the room/ home and may keep insisting he/ she wants to go home.
  • The person may be anxious about where the toilet is.
dementia patient wrong word usage - says neck for kneePersons with dementia often cannot communicate what they want. They may have problems remembering the right word, or may not know the meaning of words others use. They may not be able to frame sentences.


They may also not know what they are feeling; they may not realize they are hungry or thirsty or hot or cold, or even that they are unwell or in pain.

They may not be able to tell caregivers what they want. They may not be able to say that they are unwell or are in pain. So their needs remain unfulfilled. This may frustrate, distress, or anger them, even if they don’t know how to express it.


If they are ill, their illness will affect their ability to do things, but caregivers may not realize why the person with dementia is behaving differently today. Also, the caregiver may not realize that the person needs rest/ treatment.

dementia patient wonders whether young girl is sister or daughterIn many types of dementia, persons lose recent memories and revert to older memories. They unconsciously try to fill the gaps in their memories using their imagination.Persons with dementia cannot recognize people or places. They may not even recognize their home and family.
dementia patients find it difficult to learn new thingsOften, persons with dementia are unable to create new memories. They may also have problems understanding complex instructions or concepts.Persons with dementia may find it more difficult to learn new things, use new devices, and adjust to new places. They may get stressed when they meet new people or see new things, and they start avoiding such situations.
dementia patient covers up memory loss, pretends to recognize girlIn many types of dementia, the part of the brain that tells people how to interact socially is not damaged in the beginning. Social interaction ability deteriorates at a slower pace in most persons with dementia.Persons with dementia don’t want others to know about their problems, so they hide their memory loss and other problems by evading questions. Outsiders may therefore not believe a dementia diagnosis.
dementia patient laughs at a cremation, showing socially inappropriate behaviorThe part of the brain that regulates behavior may get damaged in some types of dementia. This may result in personality changes. The person may become “disinhibited” and not behave in socially correct ways. Emotions may get flattened and the person may show apathy. Such problems are typical in behavior-variant fronto-temporal dementia.Poor behavior regulation often leads to embarrassing situations. Friends and family around the person with dementia may think the person is now a “bad character” or is inconsiderate and insensitive. For example, the person may made rude remarks (even sexual comments), yell or abuse. Or the person may laugh when others are crying. Or the person may lose interest in everything and not respond to emotions of others nearby. Examples of disinhibition include publicly stroking or exposing genitals, making lewd gestures, lifting a petticoat or nightgown, etc.
dementia patient gets hallucinationsIn some forms of dementia, like Lewy Body Dementia, persons may suffer from hallucinations.


Delusions and paranoia are also present in some forms of dementia.

Hallucinating persons sometimes realize that what they are seeing and hearing is not real. At other times, they may believe what they are seeing or hearing because of the hallucination and get confused or frightened. Familiar tasks become difficult because they cannot distinguish between reality and hallucination. For example, if they see a road split into four, they cannot drive. Family members may not know that the person is hallucinating and hence confused/ frightened.


Delusions also affect how persons with dementia interact with others. They may accuse others of stealing their things or of trying to kill them. They may not understand explanations about what is real. It is often difficult to calm down someone who becomes paranoid because of such problems.

dementia patient repetitive behaviorPersons with dementia may repeatedly say something or do the same action again and again. They may show compulsive behavior. This is also called ‘perseveration’.


Such behavior occurs for many reasons. They may forget what they said or did earlier, they may be bored or anxious or agitated, etc.

Common examples are when the person may say the same thing repeatedly, ask the same question, make the same gesture, do the same action, call up the same friend again and again, or keep asking to “go home”, etc. Some such repetitive behavior is harmless. At other times it may be problematic. For example, the person with dementia may insist on eating breakfast again. The person may even take the medication again, causing an overdose. Repeated actions, like packing/ unpacking a suitcase or pacing a room, can be very tiring. Caregivers can get annoyed or distressed if they don’t understand why the person is acting like this.
dementia patient showing sundowningMany persons with dementia show changed behavior in the evenings/ night, called “sundowning”. This includes pacing at night, restlessness, etc. While causes for sundowning are not fully understood, they are likely to be related to day time activities, exhaustion, body clock, food cycles, intake of liquid foods near dinner time, and so on.Persons with dementia start acting agitated as evening approaches. They may keep walking up and down in their room for many hours at night. They may seem agitated and anxious. Sleeplessness is another problem. They may keep mumbling or even shouting. All this can be very tiring for them and their caregivers.
dementia patients show insecurity through behaviors like hiding, hoarding, trailing, etc.The problems caused by dementia can make persons feel insecure.


Insecure persons with dementia may cling to caregivers and show more dependence. Or they may feel threatened by the caregivers. They may try to protect themselves or even attack caregivers.

Persons with dementia may hide or hoard objects. These objects may not be valuable but they may get agitated if someone touches the objects. They may accuse others of neglect or theft or bad intentions.


Insecure persons may follow the caregiver all the time (also called shadowing) . They may get upset if they cannot follow the caregiver, such as when the caregiver goes to the bathroom. They may keep calling out to check where the caregiver is.

dementia patients may show emotional reactions that seem extreme and unprovokedPersons with dementia may show extreme emotional reactions without any apparent cause. They may withdraw from company and tell close family members to leave them alone, or shout/ scream/ show agitation and anger when nothing seems to have caused it.The emotional state of someone with dementia depends on many factors, many of which are not obvious to persons around them. This topic is discussed in the next section.

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How dementia affects the emotional state of the person

Dementia impacts the person’s emotions in several ways.

Some parts of the brain enable feeling and expressing emotions. If dementia damages these parts of the brain, it reduces the ability to regulate emotions. Also, parts of the brain help us understand facial expressions to know what others are feeling. If these are damaged, the person cannot judge the feelings of others. Persons with dementia may therefore seem uninterested or emotionally “flat.”

We behave properly in society because our brain tells us how to. This brain function may be affected in someone with dementia. If so, such persons may behave in socially “inappropriate” ways. They may abuse others, yell, laugh or cry at inappropriate times. They may take off clothes in public or pass vulgar comments. Such behavior is especially seen in the dementias where the frontal lobe is damaged.

Persons with dementia may sense they have changed. They may know about their poorer ability to think, recognize, speak, do daily tasks, etc. But they may not understand why they are having such problems. They may not understand the diagnosis or they may forget it. As a result, they may show a range of emotional reactions to their situation. They may withdraw or feel sad. Or they may get angry or agitated and shout at people. They may get restless or anxious, and pace or fidget. They may feel insecure and shadow (trail) the caregiver. They may get paranoid and fling accusations.

Memory problems mean that the person may not remember where some object is kept and therefore think someone stole it. Persons with dementia may also forget they ate a meal and demand food again or complain they are being starved. Many persons complain of mistreatment because of such problems.

The physical surroundings of the person usually remain the same even after the persons gets dementia. Family and friends around them also continue to interact like before. This makes the surroundings unsuitable because of the person’s reduced abilities. Persons with dementia find simple tasks and communication more difficult; they get distressed.

Sometimes the agitation and frustration of someone with dementia makes that person go out of control. This is called “catastrophic behavior.” Calming down someone in this state is very difficult. Dementia may even have affected the person’s ability to regulate emotions and calm down.

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Reduced cognitive abilities combine with environment and interactions to further affect behavior

Many people think that “changed behavior” is because of the person’s disease or personality. They don’t think that other factors may also be involved. They don’t see behavior as a response to many internal and external factors. As a result, they don’t change objects and interactions around the person with dementia in order to reduce behavior challenges.

Consider the physical environment around the person with dementia. This directly affects what the person can do. It determines how difficult each action is. For example, the person may not be able to find something if the room is cluttered or dimly-lit. Changes to the surroundings can make it easier for the person to do things and feel safe.

Persons with dementia are also affected by the interactions with others around them. Often family members expect the person with dementia to understand and remember instructions. They expect the person to continue doing their tasks just like they did before dementia. The person may get agitated or may withdraw because of these unrealistic expectations. Emotional responses and facial expressions of family members also affect the emotions and behavior of someone with dementia.

Dementia behavior is a combination of the person’s reduced abilities, other medical problems, and the way the person spends the day. This includes the person’s surroundings, tasks, and interactions. Behavior is not something that can become “normal” by explaining or scolding, or by giving medicines. In some cases, the symptom relief obtained with medicines can improve things especially if combined with more suitable interactions, but even with this, the person does not go back to the “normal” person he/ she was earlier.

Note that high stress, disruptive situations (like the COVID pandemic) can have a major impact on the person with dementia as they cause major changes in home and care environment and disrupt the daily routine, which can result in challenging situations of changed behavior. Multiple aspects of how to reduce infection risks and also adjust home and care environment have to be considered to reduce such impact.

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Glimpses of experiences of persons with dementia

Many depictions of persons with dementia are misleading and “stereotypical”. These may show them as vacant-eyed and passive (“just not there,” “absent”). Or they may show them as persons who are always angry, stubborn, and even violent. Such depictions create a stigma. They generalize all dementia persons in one extreme way. Once people hear that someone has dementia, they assume the person has changed totally. This is wrong. Please do not get influenced by these simplistic phrases and depictions.

Persons with dementia are just persons facing more problems than others around them. They are trying to cope. Like everyone else, they want meaningful and happy lives. If given a suitable empowering environment and support, they can have a better life. Their problems will keep increasing, and they will need more understanding and support.

Some persons with dementia have written about their experiences and feelings. They have described their problems, confusion, frustration, and reduction in abilities. They have also talked abut how relieved they feel on learning that their problems were because of a disease. In their personal stories, they talk of how they feel determined and good on some days, and face more difficulties and despair on others. They want to live as well as they can.

Some persons with dementia have written books about their experiences, too.

Several links to such blogs and books are included in the “See Also” section at the bottom of this page.

Imagine not knowing the place, day and time, and not recognizing people. Imagine struggling to find the correct word. Imagine wondering what is going wrong, but ashamed to admit the problems or ask for help. Imagine not knowing that these problems are because of a disease.

Only someone with dementia can know what it is like to have a confused, undependable mind and body. But some persons have used devices to give caregivers a glimpse of what living with dementia may involve. View a YouTube video with a sensitization experiment at this link: Experience 12 Minutes In Alzheimer’s Dementia Opens in new window.

Dementia awareness in India is very poor. Often, persons with dementia do not get diagnosed when facing the initial symptoms like those described in the personal stories above. They and their families expect “normal” behavior all the time. By the time the family contacts a doctor, the dementia has progressed. The concept of “Alzheimer’s Disease” or other dementias is new to the person getting the diagnosis. The person may not believe or remember the diagnosis and may continue to feel scared or ashamed. This worsens the person’s stress.

By getting a better appreciation of what persons with dementia undergo, it is possible to help them in better ways and also feel empathy.

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What caregivers can remember about dementia behavior

Some things to remember when you see changed behavior and feel uncomfortable/ bad:

  • The brain of the person with dementia has been damaged. This affects what the person can do. Just like someone with heart problems may not be able to climb stairs, a dementia person may find some “cognitive” work difficult. The person’s abilities to think, act, and remember have reduced.
  • Most people have reasons and motives for their actions. If someone said something nasty, it is usual to think he meant it. But in the case of dementia, it is wrong to assume that the person with dementia intended to be nasty. The person may not be thinking clearly, or may have spoken something because of some confusion or delusion.
  • Persons with dementia are not acting difficult because they want to trouble others. They are themselves facing problems because their brains are not cooperating with them. Anyone would behave differently if their brains were damaged.
  • If someone with dementia acts odd some day, he may be facing a problem he cannot tell us.
  • If someone with dementia gets upset and emotional, he may be frustrated. You can try to see how to help the person.
  • If someone with dementia behaves in an inappropriate way or shows apathy, that may be due to dementia. The brains regulate emotions and behavior. Damage to the brain can affect emotions and behavior.
  • The expectations and response of the persons near the dementia person can be contributing to the changed behavior.
  • The person’s physical surroundings may be causing difficulties and contributing to changed behavior.
  • Your brains are working properly. If you cannot understand what the person with dementia is doing, how can you expect the person (whose brain has problems) to understand you?
  • You can learn how to communicate with persons with dementia and to help them. You can learn how to handle challenging behavior. The persons with dementia cannot learn new things, so it is your responsibility to learn how to cope with the situation.

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Terminology around dementia behavior

Many terms are used to describe the changed behavior seen in dementia. Professionals and researchers have different preferences regarding such terms. Usage also differs across communities and countries. Also, two spellings are used: “behaviour” and “behavior”. When searching for information, you may get different results by using different search terms and combinations. Here are some of the main terms:

  • Challenging behavior, difficult behavior, and problem behavior: These terms look at the problems created by the changed behavior. The usual emphasis is the problems created for the friends and family around the person with dementia. These terms don’t point to possible reasons of the changed behavior. Using these does not remind us that the person has cognitive decline. They do not indicate that the environment or interactions may be unsuitable for the person’s situation. Basically, these terms ignore the problems of the person with dementia. Behavior is seen as a problem to be corrected. The focus is on “what” is happening rather than the “why”. However, these terms remind people that something has to be done to address the behavior. These are the most common terms used.
  • Behaviors of concern: This term is less negative than the above term. It shows ‘concern’ on whether the person with dementia or others might be harmed. It helps decide which behaviors need to be coped with. Caregivers try to resolve behaviors causing more “concern.” However, the term still focuses on “what” is happening rather than “why.” Caregivers may think “concern” means problematic for them, not for the person with dementia.
  • Needs-driven behavior: This term reminds us that the person with dementia may have an unmet need. The needs may be based on the situation or perception. This term encourages caregivers to find the unmet need and do something about it. The term carries no criticism of the person with dementia. It does not focus on whether this behavior is causing inconvenience to anyone. It shows reasonableness: the person needs something, and this need is causing the behavior.
  • Neuropsychiatric symptoms: This term is not used by caregivers. However, it is common in academic circles. Some professionals may use it when talking to patients and families. The term focuses on the symptoms and not on the inconvenience created for others. “Psychiatric” is stigmatizing in some countries. Caregivers may think that because the problem is “psychiatric,” the behavior is a “mental” problem. They may assume that the only solution is using medicines and nothing else needs to be done. Family caregivers, on hearing this term, may think the behavior is caused solely because of dementia. The “needs” angle is missed.
  • BPSD (Behavioral and Psychological Symptoms of Dementia, Behavioral and Psychiatric Symptoms of Dementia): This term is used by academics. It is also common in caregiver circles in some countries. It focuses on the symptoms and not the problems they create. It does not recognize the “need” behind the behavior. It may seem to mean that all changed behavior is because of dementia. Many specialists use “psychological”, but some use “psychiatric” when expanding BPSD. The word “psychiatric” is associated with stigma in many countries. One additional caution: a doctor may scribble BPSD on a prescription. Family members sometimes think this is a new or additional disease.

Regardless of the term used, caregivers need a better understanding of changed behavior. This enables them to find ways to reduce the stress and harm to the person with dementia and to themselves.

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See Also…

Changed behavior in dementia is discussed in many books. Some books also have tips on how to handle them. Some good books are given below:

  • Coping with Behavior Change in Dementia: A Family Caregiver’s Guide by Beth Spencer, Laurie White. This book discusses why behavior changes happen in dementia and discusses some general approaches. It looks at each possible behavior change, explains possible causes, and gives several practical tips for both preventing and handling the behavior. A go-to book for behavior challenges, and organized in a very friendly way. Highly recommended. Available on Amazon (paperback, Kindle) and free on Kindle Unlimited.
  • Breaking Dementia: Finding Acceptance and Hope for This Journey by Rick Phelps, Leeanne Chames. This book is written by someone diagnosed with Early Onset AD (Rick Phelps) and a caregiver who has cared for a mother and a mother-in-law with dementia (Leeanne Chames). Both authors are also administrators of the Facebook group, Memory People, one of the largest and more effective online support forum for dementia. The book describes difficulties experienced in dementia as explained by someone undergoing them, and helps readers appreciate how relentless, overwhelming and exhausting it is to live with dementia. The caregiver perspective suggests how to accept the situation and support the person. Written in a very honest and helpful way, this book gives a deep and realistic understanding of behaviour changes at an emotional level. Highly recommended. Available as paperback and Kindle in some countries, and as a Kindle ebook in India.
  • The 36-Hour Day – A Family Guide to Caring for People Who Have Alzheimer Disease, Other Dementias, and Memory Loss by Nancy L Mace, Peter V Rabins. This book explains many behavioral symptoms. It is a very good starting point for caregivers who want to understand the changes brought by dementia. Available as paperback and Kindle on Amazon.

Read about these books and also see our list of other book suggestions at: Books on dementia and care. This page also includes special sections like Books where Indian caregivers share personal experiences and thoughts and Books written by persons with dementia, describing their experiences of living with dementia.

Caregiver experiences from India that describe the impact of dementia can be seen in our section here: Caregiver interviews and voices.

Caregivers can get a better idea of what persons undergo when they have dementia if they read the books and blogs or view the videos by persons with dementia. Often such sharing is done by persons who have been diagnosed early and are not yet in later stages of dementia.

A collection of voices of persons with dementia is available on this page: Voices: Persons with dementia share experiences.

Caregivers can check out the Dementia Home Care: An Overview. This has discussions on how to approach care, including coping with changed behavior. If specifically interested in “challenging behaviors”, check Handling Behavior Challenges.

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As noted above, some images on this page are courtesy National Institute on Aging/National Institutes of Health Opens in new window.

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