Stages of Alzheimer’s & Dementia: Durations & Scales Used to Measure Progression: GDS, FAST & CDR

Last Updated: September 01, 2018


While Alzheimer’s disease and other common dementias, such as Vascular dementia, Dementia with Lewy bodies, and Pick’s disease, affect many aging people, these dementias are not a normal part of aging. Rather, they are diseases. While many older people are forgetful, this does not warrant a diagnosis of dementia. Dementia goes beyond simple forgetfulness. Brain changes from dementia affects one’s thought process and the ability to organize information, in addition to affecting one’s capacity for memory.


Stages of Dementia

Health professionals sometimes discuss dementia in “stages,” which refers to how far a person’s dementia or Alzheimer’s has progressed. Defining a person’s disease stage helps physicians determine the best treatment approach and aids communication between health providers and caregivers. Dementia is commonly conceived of as progressing in three stages: mild (or “early”), moderate (or “middle”), and severe (or “late”). However, often a more exact stage of dementia is assigned, based on a person’s symptoms.


Scales for Rating Dementia

Rather than simply using “mild stage”, “middle stage”, and “late stage” dementia as descriptors, there are scales that exist that are slightly more comprehensive in description. These scales allow one to better understand the different stages of Alzheimer’s disease via cognitive decline and functionally. These scales are the Global Deterioration Scale for Assessment of Primary Degenerative Dementia, the Functional Assessment Staging Test, and the Clinical Dementia Rating.


 Did You Know? Persons with Alzheimer’s or dementia can receive free assistance finding home care providers or memory care residences that match their care needs, budget and location requirements. 


Global Deterioration Scale / Reisberg Scale

The most commonly used scale is often referred to simply as GDS, or by its more formal name, the Reisberg Scale or even but the lengthy name Global Deterioration Scale for Assessment of Primary Degenerative Dementia.

The GDS scale divides the disease process into seven stages based on the amount of cognitive decline in the inflicted senior. This test is most relevant for people who have Alzheimer’s disease since some other types of dementia (i.e. Frontotemporal dementia) do not always include memory loss.

In the below scale, elders in stages 1-3 do not typically exhibit enough symptoms for a dementia diagnosis. By the time a diagnosis has been made, a dementia patient is typically in stage 4 or beyond. Stage 4 is considered “early dementia,” stages 5 and 6 are considered “middle dementia”, and stage 7 is considered “late dementia”.

Global Deterioration Scale (CGS) / Reisberg Scale
Diagnosis Stage Signs and Symptoms Expected Duration of Stage
No Dementia Stage 1:
No Cognitive Decline
In this stage, the person functions normally, has no memory loss, and is mentally healthy. People with NO dementia would be considered to be in Stage 1. N/A
No Dementia Stage 2:
Very Mild Cognitive Decline
This stage is used to describe normal forgetfulness associated with aging. For example, forgetting names and where familiar objects were left. Symptoms of dementia are not evident to the individual’s loved ones or their physician. Unknown
No Dementia Stage 3:
Mild Cognitive Decline
This stage includes increased forgetfulness, slight difficulty concentrating, and decreased work performance. People may get lost more frequently or have difficulty finding the right words. At this stage, a person’s loved ones will begin to notice a cognitive decline. Average duration of this stage is between 2 years and 7 years.
Early-stage Stage 4:
Moderate Cognitive Decline
This stage includes difficulty concentrating, decreased memory of recent events, and difficulties managing finances or traveling alone to new locations. People have trouble completing complex tasks efficiently or accurately and may be in denial about their symptoms. They may also start withdrawing from family or friends because socialization becomes difficult. At this stage, a physician can detect clear cognitive problems during a patient interview and exam. Average duration of this stage is 2 years.
Mid-Stage Stage 5:
Moderately Severe Cognitive Decline
People in this stage have major memory deficiencies and need some assistance to complete their daily living activities (dressing, bathing, preparing meals, etc.). Memory loss is more prominent and may include major relevant aspects of current lives. For example, people may not remember their address or phone number and may not know the time or day or where they are. Average duration of this stage is 1.5 years.
Mid-Stage Stage 6:
Severe Cognitive Decline (Middle Dementia)
People in Stage 6 require extensive assistance to carry out their Activities of Daily Living (ADLs). They start to forget names of close family members and have little memory of recent events. Many people can remember only some details of earlier life. Individuals also have difficulty counting down from 10 and finishing tasks. Incontinence (loss of bladder or bowel control) is a problem in this stage. Ability to speak declines. Personality / emotional changes, such as delusions (believing something to be true that is not), compulsions (repeating a simple behavior, such as cleaning), or anxiety and agitation may occur. Average duration of this stage is 2.5 years
Late-Stage Stage 7:
Very Severe Cognitive Decline (Late Dementia)
People in this stage have essentially no ability to speak or communicate. They require assistance with most activities (e.g., using the toilet, eating). They often lose psychomotor skills. For example, the ability to walk. Average duration of this stage is 1.5 to 2.5 years.

Functional Assessment Staging Test (FAST)

The Functional Assessment Staging Test (FAST) is another scale that is used to describe the stages of dementia. Like the GDS Scale, FAST also employs a seven-stage system based on one’s level of functioning and ability to perform daily living activities. However, FAST focuses more on an individual’s level of functioning and activities of daily living versus cognitive decline. Note: A person may be at a different stage cognitively (GDS stage) than functionally (FAST stage).

Functional Assessment Staging Test (FAST)
Stage Patient Condition Level of Functional Decline Expected Duration of Stage
Stage 1 Normal adult No functional decline. N/A
Stage 2 Normal older adult Personal awareness of some functional decline. Unknown
Stage 3 Early Alzheimer’s disease Noticeable deficits in demanding job situations. Average duration of this stage is 7 years.
Stage 4 Mild Alzheimer’s Requires assistance in complicated tasks such as handling finances, traveling, planning parties, etc. Average duration of this stage is 2 years.
Stage 5 Moderate Alzheimer’s Requires assistance in choosing proper clothing. Average duration of this stage is 1.5 years.
Stage 6 Moderately severe Alzheimer’s Requires assistance with dressing, bathing, and toileting. Experiences urinary and fecal incontinence. Average duration of this stage is 3.5 months to 9.5 months.
Stage 7 Severe Alzheimer’s Speech ability declines to about a half-dozen intelligible words. Progressive loss of ability to walk, to sit up, to smile, and to hold head up. Average duration of this stage is 1 year to 1.5 years.

Clinical Dementia Rating (CDR)

The Clinical Dementia Rating (CDR) scale uses a five-point system based on cognitive (thinking) abilities and the individual’s ability to function. This scale is more commonly used in dementia research and less so as a communication tool between medical professionals, patients, and their families. This is the most widely used staging system in dementia research. Here, the person with suspected dementia is evaluated by a health professional in six areas: Memory, orientation, judgment and problem solving, community affairs, home and hobbies, and personal care. Based on semi-structured interviews with the potential dementia patient and others, such as a family member, one of five possible stages is assigned to the individual in question.

Clinical Dementia Rating (CDR) Scale
Stage Description Expected Duration of Stage
CDR-0 No Dementia N/A
CDR-0.5 Very Mild Dementia – Memory problems are slight, but consistent. Individuals have some difficulty with time and problem solving, and one’s daily life is slightly impaired. Individuals are still fully capable of performing personal care activities. Average duration is a few years up to 7 years.
CDR-1 Mild Dementia – Memory loss is moderate, especially for recent events, and interferes with daily activities. Individuals have moderate difficulty with solving problems, they cannot function independently at community affairs, and they have difficulty with daily activities and hobbies, especially complex ones. Average duration is 2 years.
CDR-2 Moderate Dementia – More profound memory loss, only retaining highly learned material. Individuals are disoriented with respect to time and place, they lack good judgment, and have difficulty handling problems. They have little to no independent function at home and can only do simple chores and have few interests. Average duration is just under 2 years to 4 years.
CDR-3 Severe Dementia – Severe memory loss. Individual are not oriented with respect to time or place, they have no judgment or problem solving abilities, and they cannot participate in community affairs outside the home. They require help with all tasks of daily living and require help with most personal care. They are often incontinent.

Average duration is 1 year to 2.5 years.


Duration of Stages: How Long do the Stage of Alzheimer’s / Dementia Last

No individual with dementia experiences the progression of the disease in the exact same way, and the rate of progression will vary by person and the type of dementia. In addition, it is not uncommon for individuals to have mixed dementia, meaning they have more than one type of dementia. That said, there is a natural course of the disease, and overtime, the capabilities of all persons with dementia will worsen and eventually the ability to function will cease. Keep in mind, changes in the brain of a dementia patient begins years before a diagnosis is made, and during this timeframe, there are no outward signs of dementia.

Life Expectancies by Dementia Type
Dementia Type Life Expectancies
Alzheimer’s Disease 10 years following diagnosis
Vascular dementia 5 years following diagnosis
Dementia with Lewy Bodies 2 to 8 years following pronounced symptoms


Mild Dementia

In this early stage of dementia, an individual can still function rather independently, and often is still able to drive and maintain a social life. In the very early stage of dementia, symptoms that are seen may be attributed to the normal process of aging. For instance, there might be slight lapses in memory, such as having difficulty finding the word for something or misplacing eyeglasses. Other difficulties may include issues with planning, organizing, concentrating on tasks, or accomplishing parts of employment, if the individual is still in the workforce. This early stage of dementia, on average, lasts between 2 and 4 years.

Moderate Dementia

In this middle stage of dementia, which in most cases is the longest stage of the disease, brain damage is extensive enough that a person has trouble expressing their thoughts, performing daily tasks, and has more severe memory issues than in the earlier stage. An individual in this stage might not remember their address, might be unable to recall their personal history, and may get confused as to their location. Communication becomes difficult and the individual may lose track of their thoughts, may be unable to follow conversations, and may have trouble understanding what others are trying to communicate. Mood and behavior changes, such as aggressiveness, difficulty sleeping, depression, paranoia, repeating actions and / or words, hoarding, anger, wandering, incontinence, and frustration may be seen. This moderate stage of dementia, on average, lasts between 2 and 10 years.

Severe Dementia

In late stage dementia, also known as advanced dementia, individuals have significant issues with communication, often using only words or expressions. At the very end, they may not verbally communicate at all. Memory also worsens and individuals may not be able to remember what they had for lunch, recall who family members are, or they may think they are in a different time period all together. For instance, they might revert back to their childhood days. Individuals may no longer be able to walk and will require extensive assistance with daily living activities, such as personal hygiene and eating. At the very end of this stage, the individual will most likely be bedridden. This severe stage of dementia lasts approximately 1 to 3 years. According to the Alzheimer’s Association (2018), for individuals with dementia, approximately 40% of their time is spent in this last stage of dementia.


Care Requirement by Stage

At first diagnosis of dementia, an individual may not require care assistance, but as the disease progresses and an individual’s symptoms become worse, care will be needed. Eventually, the individual will not be able to care for him / herself at all. According to the Alzheimer’s Association (2018), there are 16.1 million unpaid caregivers of people with dementia in the United States. While many Americans are caregivers for loved ones, many people also hire someone to provide care or supplement the care they are already providing. There are many options of care assistance, such as in-home care, adult day care, and nursing home care, and there is also financial assistance available.

Early Stage Dementia

As mentioned previously, in the early stage of dementia, a person can still function rather independently and requires little care assistance. Simple reminders of appointments and names of people may be needed. Caregivers can also assist with coping strategies to help loved ones remain as independent as possible, such as writing out a daily to-do list and / or a schedule of when medications should be taken. Safety should always be considered, and if there are any tasks that a person with early stage dementia cannot perform safely on their own, supervision and / or assistance should be provided. During this period of dementia, it’s a good idea for caregivers and loved ones to discuss and make decisions about the future. For example, a long-term care plan should be made and financial and legal matters put in place.

Middle Stage Dementia

In the middle stage of dementia, an individual no longer is able to function as independently as in the earlier stage. Assistance with activities of daily living, such as bathing, grooming, and dressing, is often required. Initially, an individual may only need prompts or cues to perform these tasks, such as reminders of the need to shower or clothes laid out on the bed. However, at some point, more hands on assistance will be required. Establishing a routine becomes important and caregivers need to exercise patience. Since individuals in this stage of dementia have greater difficulty communicating, caregivers need to talk slowly, clearly, and at times, use non-verbal communication. Individuals will no longer be able to drive, so transportation will be required. It is also in this stage of dementia when it becomes no longer safe to leave the individual alone, which means supervision is necessary.

Late Stage Dementia

A person in this last stage of dementia requires a significant amount of care, and assistance and supervision is required 24-hours / day. Dementia patients may require assistance getting in and out of bed, moving from the bed to a chair, or may be bedridden and require help moving positions to avoid bedsores. Swallowing becomes an issue in late stage dementia, and caregivers have to make sure food is cut into small pieces, is soft, such as yogurt and applesauce, or is pureed. At some point, the individual will be 100% dependent on their caregiver and will no longer be able to complete any daily living activities on their own. Not all families are equipped to offer this level of care. As mentioned previously, there are other options for care, such as hiring a part time caregiver or moving your loved one to a nursing home.

  For more information on caring for individuals with dementia, click here. It’s important to remember, providing care for a loved one can be stressful, and self-care is a must. Click here to learn about ways to deal with stress, finding support, and more.