6: Dementia severity and progression

Symptoms of dementia will vary between people and can vary day to day for the same person. However, each person will experience progressive cognitive and physical decline. The rate of decline will vary due to numerous factors such as personal characteristics, dementia type, age at diagnosis, existing health conditions, care and living arrangements and access to health services.

Data on severity and rate of progression will indicate the level of support required, when increases in support are projected to be needed, and may support research into risks for more rapid progression, or eligibility for clinical trials or treatment.

There is no consistent classification of dementia severity and various models are used. In the 3-stage dementia severity model:

  • mild dementia is defined by cognitive impairment and poor performance on objective cognitive assessments that represent a decline from the past; however, independence in basic activities of daily living is maintained
  • moderate dementia has more distinct symptoms and impacts on activities of daily living
  • advanced dementia includes health and functional declines requiring assistance in activities of daily living.

Other classification systems use 7 stages that include stages occurring before a dementia diagnosis (Reisberg et al. 1982).

Data on dementia severity and progression will inform service needs and planning and may assist in assessing the effectiveness of interventions designed to reduce or slow dementia progression, and factors leading to increased severity or progression. Current data focus on functional abilities and level of assistance required to perform tasks across different domains (such as self-care, mobility and communication). These data are currently captured in aged care assessment data and the Australian Bureau of Statistics’ (ABS) National Survey of Disability, Ageing and Carers. Aged care assessment data also contain some information on current levels of support, daily life, health, behaviours, memory and goals (My Aged Care).

In addition, there is a lack of information about people in the early stages of dementia or cognitive impairment, including the diagnosis and early disease management process due to poor recognition of symptoms and early assessment (as outlined in Timeliness of dementia diagnosis). Current data sources tend to capture people with more severe dementia, when they engage with hospital and aged care services.

Behavioural and psychological symptoms of dementia

Behavioural and psychological symptoms of dementia (BPSD) refer to non-cognitive symptoms (such as aggression, agitation, apathy, depression and disinhibited behaviours), that are common across all types of dementia and have no singular cause. The type and severity of symptoms can vary over the course of the illness, and on a day-by-day basis. The symptoms can have a major impact on the person with dementia and their carers (AIHW 2023). 

Most people living with dementia will experience at least some level of BPSD as their dementia progresses. BPSD has a range of non-cognitive symptoms and is often associated with complex care needs. The Neuropsychiatric Inventory (NPI) is the primary measure of BPSD within clinical settings in Australia. It assesses a wide range of behaviours, rating severity, frequency, and carer distress for 12 domains. Currently, Dementia Support Australia are the only national data source that collect NPI information for people who experience BPSD, however, these are only of people accessing their services. However, some data on select behaviours are captured in aged care assessment data. 

Improved data on BPSD will inform planning for the health and aged care systems including national behaviour support programs currently managed by Dementia Support Australia such as the Dementia Behaviour Management Advisory Service, Severe Behaviour Response Teams, and the Specialist Dementia Care Program (AIHW 2023).

Proposed data improvement activities

There are 4 main activities proposed to improve available data on dementia severity and progression. These include activities to: 

  • incorporate dementia data in enduring linked data assets to meet the needs of dementia monitoring (Activity 3a detailed under Dementia prevalence and incidence)
  • determine outcomes and transitions of care for people with BPSD using linked data
  • validate data on select behaviours collected in aged care assessment data
  • assess feasibility to incorporate measures of behaviours associated with dementia in existing national surveys or population-based studies.

Each activity provides information on the intended outcome, priority rating, level of investment required, timeframe for completion of the activity and who is responsible for undertaking the activity.