Dementia is a syndrome, classed as a major neurocognitive disorder often associated with neurodegenerative diseases such as Alzheimer's, and characterized by a general decline in cognitive processes that affects the ability to perform everyday activities. This typically involves problems with memory, thinking, behavior, and motor control. Aside from memory impairment and a disruption in thought patterns, the most common symptoms of dementia include emotional problems, difficulties with language, and decreased motivation. The symptoms may be described as occurring in a continuum over several stages. Dementia is an incurable, progressive disorder, with varying degrees of severity (mild to major) and many forms or subtypes. The condition has a significant effect on the individual, their caregivers, and their social relationships in general. Dementia is not the same as age-related decline in cognition and memory, with no change in intelligence.
The most common form of dementia is Alzheimer's. Dementia can be caused by brain injuries and stroke. It has also been described as a spectrum of disorders with subtypes of dementia based on which known disorder caused its development, such as Parkinson's disease for Parkinson's disease dementia, Huntington's disease for Huntington's disease dementia, vascular disease for vascular dementia, HIV infection causing HIV dementia, frontotemporal lobar degeneration for frontotemporal dementia, Lewy body disease for dementia with Lewy bodies, and prion diseases. Subtypes of neurodegenerative dementias may also be based on the underlying pathology of misfolded proteins, such as synucleinopathies and tauopathies. The coexistence of more than one type of dementia is known as mixed dementia.
Diagnosis is usually based on history of the illness and cognitive testing with imaging. Imaging can help to determine the dementia subtype, and to exclude other causes. Blood tests are usually taken to rule out other possible reversible causes such as hypothyroidism (an underactive thyroid). Fluid biomarkers detected in cerebrospinal fluid, and in blood can identify Alzheimer's disease. PET scans can detect amyloid beta and tau, the two intrinsically disordered proteins that are the hallmark features of Alzheimer's.
Although the greatest risk factor for developing dementia is aging, dementia is not a normal part of the aging process; many people aged 90 and above show no signs of dementia. Risk factors, diagnosis and caregiving practices are influenced by cultural and socio-environmental factors. Several risk factors for dementia, such as smoking and obesity, are modifiable by lifestyle changes.
, dementia is the seventh leading cause of death worldwide and has 10 million new cases reported every year (approximately one every three seconds). In the UK it is the leading cause of death. It is one of the main causes of disabilities in those aged over 65. There is no known cure for dementia.
Acetylcholinesterase inhibitors such as donepezil are often used in some dementia subtypes and may be beneficial in mild to moderate stages, but the overall benefit may be minor. There are many measures that can improve the quality of life of a person with dementia and their caregivers. Cognitive behavioral therapy may give some benefit for treating the associated symptoms of depression.
Signs and symptoms The signs and symptoms of dementia may vary between individuals, and may vary according to the underlying subtype, particularly in the early stages but at the end stage of all types they are similar. Symptoms may be grouped into three areas: cognitive, neuropsychiatric (behavioral and psychological), and motor.
The cognitive symptoms of dementia relate to the area of the brain affected. Typically this includes memory plus one other cognitive region affecting language (commonly), attention, problem solving or perception and orientation. Signs of dementia include wandering, and getting lost in a familiar neighborhood, using unusual words to refer to familiar objects, forgetting the name of a close family member or friend, forgetting old memories, forgetting to pay bills, and being unable to complete tasks independently. The symptoms progress at a continuous rate over several stages. Most types of dementia are slowly progressive with some deterioration of the brain well established before signs become apparent.
Neuropsychiatric symptoms (NPS) are a major feature of dementia affecting more than 90% of all cases, at different stages. They often present as first or early symptoms or syndromes, as mild behavioral impairment (MBI) that may reflect the subtype of dementia at issue. For example, a study has found that the first symptoms as NPS of personality change, and disinhibition will relate to a diagnosis of frontotemporal dementia. The presence of MBI on its own is not a cognitive impairment and is not recognized as dementia but may be an indicator for the development of mild cognitive impairment, as a predementia type. It may also be seen as a transitional state in the development of dementia.
The behavioral symptoms can include agitation, restlessness, inappropriate behavior, disinhibition, and verbal or physical aggression.
Psychological symptoms can include depression, hallucinations, delusions, apathy, and anxiety. Also common are personality changes with the progression of dementia, such as increases in neuroticism (negativity), and a decline in conscientiousness.
Motor symptoms and signs may include changes in gait, repetitive movements, parkinsonism, or seizures. Changes in gait can be responsible for falls. An inability to relax muscles, known as paratonia is an induced motor dysfunction that affects most people with dementia. Motor impairments are correlated with cognitive impairments, and are a main cause of disability and dependency. In advanced dementia paratonia may lead to fixed postures with contracted muscles, which can lead to broken skin, and infection, and also cause pain on movement. This type of motor disorder is not the same as that found in Lewy body dementias.
Stages The course of dementia is generally described in three major stages (early or mild, middle or moderate, and late or severe) that show a pattern of progressive cognitive and functional impairment. Other more detailed scales outline five or seven stages. A prodromal stage, or pre-dementia stage may also be included. With Alzheimer's disease an asymptomatic preclinical stage may precede the onset of symptoms in the prodromal stage. A preclinical stage can be identified by the presence of noted brain changes of Alzheimer's disease but this stage does not always develop into dementia. As of 2024 this stage is now classed as Clinical Stage 1.
Different scales used to assess the stage of dementia include the Global Deterioration Scale (GDS) that uses seven stages in the progression, with mild (early) dementia only appearing as stage 4. Two other scales used in relation to GDS are the Brief Cognitive Rating Scale (BCRS), and the Functional Assessment Staging Tool (FAST). The BCRS is a quick assessment that coincides with the GDS. It uses five axes in assessment – concentration, memory (recent and past), orientation, functioning and self-care. FAST places more emphasis on functioning in daily living. Another scale used is the Clinical Dementia Rating (CDR) scale originally designed just for Alzheimer's, that evaluates six main areas including memory, judgement, problem-solving, and personal care.
Prodromal A prodromal stage is a mild cognitive impairment (MCI) stage of pre-dementia, and may include mild behavioral impairment. Signs and symptoms at the prodromal stage may be subtle, often only becoming apparent in hindsight.
Mild cognitive impairment may progress to a dementia subtype; changes in the person's brain have been happening for a long time, but the symptoms are just beginning to appear, and are not severe enough to affect daily function. If and when they do, the diagnosis becomes one of a causative dementia subtype, such as minor neurocognitve disorder of Lewy body disease, for example. The person may have some memory problems and trouble finding words, but they can solve everyday problems and competently handle their life affairs.
Mild cognitive impairment has been relisted in both DSM-5 and ICD-11 as "mild neurocognitive disorder", a milder form of a major neurocognitive disorder (dementia). MCI does not always progress to dementia, as sometimes symptoms resolve.
Early In the early or mild stage of dementia, symptoms become noticeable to other people, and begin to interfere with daily activities, but only some help is needed. During this stage, it is good practice to ensure that advance care planning including advance directives are discussed.
Dementia subtypes affect different regions of the brain which in the early stage means that the symptoms are varied between individuals. The symptoms of early dementia usually include memory difficulty, but can also include some problems with language. Managing finances may prove difficult. Other signs might be getting lost in new places, repeating things, and personality changes.
Middle In the middle or moderate stage symptoms become more pronounced and more support will be needed with daily activities. Memory impairment worsens and frequent reminders may be needed. There may be difficulty in the recognition of familiar people. Holding onto new information becomes more difficult, causing questions to be continually repeated. In the middle stage word retrieval may be a problem; forgetting what they are saying in mid-sentence, and it may be harder to follow what is being said.
In neurodegenerative dementias a lack of insight into having the condition will become evident.
Late People with late-stage, or severe, dementia typically turn increasingly inward and need assistance with most or all of their personal care. 24-hour supervision to meet basic needs and ensure personal safety is usually needed. If left unsupervised, they may wander or fall, fail to recognize common dangers such as a hot stove, or fail to realize that they need to use the bathroom and become incontinent. Both urinary and fecal incontinence may become prominent features that can prove challenging for both the person affected and the caregiver. They may not want to get out of bed, or may need assistance doing so. They may also struggle to walk. Commonly, the person no longer recognizes familiar faces. Sleep disturbances become more common and worsen in this stage.
Changes in eating frequently occur. Cognitive awareness is needed for eating and swallowing and progressive cognitive decline in advanced dementia, can result in eating and swallowing difficulties. This can cause food to be refused, or choked on, and help with feeding will often be required. For ease of feeding, food may be liquidized into a thick purée. The use of a feeding tube is not recommended; there are many complications and unwanted consequences associated with tube feeding.
Paradoxical lucidity, an unexpected transient recovery of mental clarity, can occur in some cases. Terminal lucidity may manifest shortly before death.
Types