Dementia

Dementia is a clinical syndrome associated with numerous neurodegenerative and medical conditions, characterised by a progressive decline in cognitive abilities that interferes with a person’s capacity to carry out everyday activities. It typically involves impairments in memory, thinking, behaviour and motor control, and may also manifest through emotional changes, language difficulties and decreased motivation. Dementia represents a significant health challenge affecting not only the individual but also caregivers, families and wider social relationships.
Although ageing is the greatest risk factor, dementia is not considered a normal consequence of ageing. Diagnosis requires evidence of cognitive decline greater than expected for age and previous functioning, with symptoms occurring along a continuum that progresses through several stages. Dementia is a life-limiting condition and is currently among the leading causes of death worldwide.

Causes and Subtypes

Dementia arises from damage to brain cells caused by various diseases or injuries. Alzheimer’s disease is the most common cause, followed by vascular dementia, dementia with Lewy bodies, and frontotemporal dementia. Many forms are related to neurodegenerative processes, often involving misfolded proteins such as tau or alpha-synuclein.
Subtypes of dementia correspond closely to their underlying aetiologies, including:

• Alzheimer’s disease dementia – marked by amyloid and tau pathology
• Vascular dementia – associated with cerebrovascular disease or stroke
• Lewy body dementia – linked to synucleinopathies
• Parkinson’s disease dementia – occurring in advanced Parkinson’s disease
• Frontotemporal dementia – resulting from frontotemporal lobar degeneration
• Huntington’s disease dementia – caused by Huntington’s disease
• HIV-associated dementia – related to advanced HIV infection
• Prion disease-related dementias

Coexistence of multiple pathological processes leads to mixed dementia, a common presentation in older adults.
Dementia may also be secondary to potentially reversible medical conditions, including endocrine disorders such as hypothyroidism, nutritional deficiencies such as thiamine or vitamin B3 deficiency, infections, tumours, immune conditions, and metabolic or neurological diseases. Identifying these causes is crucial as cognitive deficits may improve once the primary disorder is treated.

Diagnosis and Assessment

Diagnosis relies on clinical evaluation, including medical history, observation of behavioural changes, and structured cognitive assessments. Neuropsychological testing, such as the Mini-Mental State Examination (MMSE), helps quantify cognitive impairment. Blood tests are often used to exclude reversible conditions, while neuroimaging techniques assist in identifying specific dementia subtypes and ruling out structural abnormalities.
Dementia is classified within neurocognitive disorders in the DSM-5, distinguished as mild or major depending on the severity of functional impairment.

Risk Factors and Prevention

While ageing remains the most prominent risk factor, several modifiable lifestyle factors influence dementia risk. These include smoking, physical inactivity, excessive alcohol consumption, obesity and untreated hypertension. Encouraging healthy lifestyle habits may reduce incidence in the general population, although population-wide screening for dementia has not shown clear benefit.
Globally, the disorder has an expanding prevalence, with tens of millions affected and around ten million new cases annually. The societal and economic impact continues to grow, particularly with increasing life expectancy worldwide.

Signs and Symptoms

The clinical presentation of dementia varies depending on subtype and the regions of the brain affected. Symptoms tend to cluster into cognitive, neuropsychiatric and physical domains.
Cognitive symptoms commonly include:

• progressive memory impairment
• language difficulties
• reduced attention and concentration
• impaired problem-solving
• visuospatial deficits affecting perception and orientation

Signs may include repeated loss of familiar routes, unusual word use, forgotten names of close family members, loss of old memories and difficulty completing routine tasks independently. A decline in financial skills is often an early marker, sometimes reflected in missed payments or credit issues.
Behavioural and psychological symptoms are frequent and include agitation, restlessness, inappropriate or disinhibited behaviour, aggression, depression, hallucinations—most often visual—delusions, apathy and anxiety. Such symptoms often arise from unmet needs, physical discomfort or environmental stressors and may improve with non-pharmacological interventions, such as caregiver support, structured routines and appropriate exercise.
Physical manifestations may include changes in gait, falls, repetitive movements, parkinsonism and seizures. Incontinence is significantly more common in people with dementia, alongside difficulties with eating, drinking and swallowing, leading to weight loss. Pain is also prevalent but frequently under-recognised due to communication difficulties, sometimes presenting instead as behavioural change. Many individuals live with additional medical conditions, including hypertension, diabetes, frailty and sarcopenia, complicating management.

Staging and Progression

Dementia progresses gradually over time, typically described in four broad stages: pre-dementia, early, middle and late. More detailed staging systems offer finer distinctions:

• Global Deterioration Scale (GDS)
• Functional Assessment Staging Tool (FAST)
• Brief Cognitive Rating Scale (BCRS)
• Clinical Dementia Rating (CDR)

The GDS divides the course into seven stages, with the final stage further subdivided to describe advanced functional decline.
During the pre-dementia phase, individuals may exhibit subtle sensory changes or mild cognitive impairment (MCI). Loss of smell is one of the earliest indicators of neurodegenerative decline and may precede clinical symptoms by up to ten years. This anosmia may be associated with weight loss, nutritional challenges and depression. Mild behavioural impairment (MBI) may also appear as an early prodromal condition involving persistent mood or personality changes.
The early stage involves mild cognitive impairment interfering with complex tasks, followed by loss of independence in instrumental activities. The middle stage brings more pronounced impairments, greater behavioural symptoms and increased care needs. The late stage is characterised by severe cognitive decline, near-total dependency and extensive physical complications.

Management and Care

There is no cure for dementia, though treatments can alleviate symptoms or slow progression in some cases. Acetylcholinesterase inhibitors, such as donepezil, may provide modest benefit in early to moderate stages of certain dementias. Non-pharmacological strategies are central to care, including structured environments, caregiver education, cognitive stimulation and exercise programmes. Psychological therapies, including cognitive behavioural therapy, can help manage associated depression or anxiety.
Holistic management focuses on maintaining quality of life, addressing comorbidities, managing pain and ensuring safe, supportive living arrangements. A person-centred approach is crucial, empowering individuals and caregivers throughout the course of the illness.