Dementia

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. …

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.

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). …

Most types of dementia including Alzheimer's (the most common), Lewy body dementias, and frontotemporal dementia are neurodegenerative diseases, with protein misfolding as a cardinal feature. The next most common type of dementia after Alzheimer's is vascular dementia, a cerebrovascular disease. These are the main primary types. Secondary types of dementia are secondary to a pre-existing condition, such as Huntington's dementia secondary to Huntington's disease, and HIV-associated dementia secondary to HIV. Different dementias have different causes and risk factors. But all types are characterized by loss of neurons, and consequent functioning. Depressive cognitive disorder, formerly pseudodementia, describes dementia-like symptoms as a dementia secondary to a psychiatric condition especially to clinical depression.

Alzheimer's dementia is caused by Alzheimer's disease, and accounts for 60–70% of cases of dementia worldwide. Alzheimer's is often part of a mixed dementia diagnosis, typically together with vascular dementia, but also with Lewy body dementia. Mixed dementia has been acknowledged to be the most common type of dementia.

A preclinical stage is described for Alzheimer's which is asymptomatic but which shows evidence of Alzheimer's pathology. This can precede the prodromal stage where symptoms become apparent. The loss of the sense of smell (anosmia) is recognized as a long prodromal stage in Alzheimer's.

Symptoms may vary among individuals. Typically one of the first signs is a problem with memory. Other cognitive impairments can include difficulty in finding the right word, difficulties with visuospatial ability, and impaired reasoning and judgment. In the middle stage hallucinations may be a feature. In later stages the symptoms become more severe, and include greater confusion, and changes in behavior. A lack of insight into having a condition will become evident.

The hallmark features of Alzheimer's disease are the deposits of amyloid beta in extracellular amyloid plaques, and the intracellular neurofibrillary tangles formed by hyperphosphorylated tau proteins. A protein (TREM2) malfunction can affect the microglial role of clearing cellular debris, allowing a build up of debris and plaques. …

Secondary dementias are those that develop from another condition, and include chronic traumatic encephalopathy, Huntington's disease dementia, HIV-associated neurocognitive disorder, prion diseases, and alcohol use disorder.

Huntington's disease is a neurodegenerative disease caused by mutations in a single gene HTT, that encodes for huntingtin protein. Symptoms include cognitive impairment that usually declines further into dementia. Other symptoms include chorea (jerky movements), memory lapses, depression, stumbling and clumsiness, mood swings, and behavior changes such as impulsivity and irritability that can become more aggressive in later stages.

HIV-associated neurocognitive disorder (HAND) results as a late stage from HIV infection, and mostly affects younger people. The essential features of HAND are disabling cognitive impairment accompanied by motor dysfunction, speech problems and behavioral change. Cognitive impairment is characterised by mental slowness, trouble with memory and poor concentration. Motor symptoms include a loss of fine motor control leading to clumsiness, poor balance and tremors. Behavioral changes may include apathy, lethargy and diminished emotional responses and spontaneity. HAND is the predominant form, and HIV-associated dementia is rare.

Prion diseases typically cause dementia that worsens over weeks to months. Prion diseases are very rare and include Creutzfeldt–Jakob disease, Gerstmann–Sträussler–Scheinker syndrome, and fatal familial insomnia. Prions are misfolded proteins, that cause other proteins to misfold, and build up in the brain.

Alcohol-related dementia, occurs as a result of alcohol-related brain damage due to alcoholism. Different factors can be involved in this development including thiamine deficiency and age vulnerability. A degree of brain damage is seen in more than 70% of cases of alcoholism. Brain regions affected are similar to those that are affected by aging, and also by Alzheimer's. Regions showing loss of volume include the frontal, temporal, and parietal lobes, as well as the cerebellum, thalamus, and hippocampus. This loss can be more notable, with greater cognitive impairments seen in those aged 65 years and over.

Autoimmune dementias of autoimmune disorder origin can mimic subtypes of dementia. …

The symptoms of dementia may vary depending on the underlying subtype, and between individuals, particularly in the early stages but at the end stage of all types they are similar. Diagnosis by symptoms alone is difficult, made more so when there is more than one type. A medical history will be taken, and cognitive testing carried out. Blood tests can rule out possible treatable causes such as vitamin deficiencies and hormone imbalances, or rule in probable Alzheimer's. One or more types of scan may also be needed. The DSM5 (2013) published by the American Psychiatric Association gives the diagnostic criteria for a primary dementia as the recognition of a significant decline in one or more cognitive domains that interfere with the ability to carry out everyday activities; the cognitive deficits are not exclusive to delirium, and are not explained by mental disorders such as schizophrenia, and major depressive disorder.

A number of brief cognitive tests (5–15 minutes) are available that are reasonably reliable but results need to take into account the influence of a person's educational level. The mini–mental state examination (MMSE) is the best studied and most commonly used test. This is useful in diagnosis if the results are interpreted along with an assessment of a person's personality, their ability to perform activities of daily living, and their behavior. Other cognitive tests include the abbreviated mental test score (AMTS), the modified mini–mental state examination (3MS), the Cognitive Abilities Screening Instrument (CASI), the Trail-making test, and the clock drawing test.The Montreal Cognitive Assessment (MoCA) is a reliable screening test and is freely available online in many languages. The MoCA has also been shown to be somewhat better at detecting mild cognitive impairment than the MMSE. An adapted version is available, suitable for those with hearing loss, that avoids the need for people to listen and respond to questions. RUDAS, the Rowland Universal Dementia Assessment Scale, is a short dementia screening test for use in diverse multi-ethnic communities designed to overcome language and cultural differences. An integrated cognitive assessment (CognICA) is a five-minute test that is highly sensitive to the early stages of dementia, and uses a mobile app deliverable to an iPad. …