It’s a jungle out there: the natural history of behavioural and psychological symptoms of dementia


Behavioural and Psychological Symptoms of Dementia, or BPSD, is a catch-all super-jargon term that is often the subject of academic dementia studies.

BPSD lumps together a variety of symptoms, many of which cause distress and suffering to people with dementia and their loved ones, and can be difficult to manage by professional and family carers.

The symptoms range from:

  • those related to mood, such as
    • depression,
    • anxiety
    • and apathy
  • to “hyperactive” symptoms, such as
    • irritation,
    • aggression,
    • agitation
    • and wandering.

As these symptoms vary so widely in their impact and treatment options, it seems likely that they are only studied together for convenience.

A recent literature review in the British Journal of Psychiatry (van der Linde et al, 2016 and 2016b) aimed to determine the longitudinal course of BPSD in older people with dementia or cognitive impairment. Two recent, similar reviews were limited to studies of care-home residents, and both concluded that the course of BPSD varied considerably between studies and between individual symptoms. I wonder if it was realistic to expect that widening the scope of this review to include studies of BPSD in people in other settings would tell a different story. The reviewers also intended to stratify the population by severity of dementia to give a clearer picture of the incidence and persistence of the symptoms at different stages of the disease.

This new review investigated the longitudinal course of behavioural and psychological symptoms of dementia in older people with dementia or cognitive impairment.

This new review investigated the longitudinal course of behavioural and psychological symptoms of dementia in older people with dementia or cognitive impairment.


Observational or intervention studies with a control group were eligible for inclusion if they measured the incidence and persistence of one or more of the symptoms or an association with cognitive impairment, and measured symptoms at three or more time points.

The twelve symptoms included in the search strategy were divided into five domains:

  1. Mood-related: Apathy, depressive symptoms, and anxiety
  2. Psychotic: delusions, hallucinations, and misidentifications
  3. Hyperactive: irritability, aggressive and non-aggressive agitation, and wandering
  4. Elation
  5. Sleep problems

The researchers used standardised procedures for the literature search and data extraction, but did not do any quality assessment, such as risk of bias. They didn’t register a protocol, which presumably means they didn’t write one. Perhaps this made them feel free to narrow the study eligibility criteria post-hoc due to the wide variety of objectives and methods of the studies identified by the search. The eligibility criteria were narrowed retrospectively to exclude studies:

  • with less than a three-month follow-up
  • that only measured prevalence at the different time points, rather than incidence
  • that used caregiver-reported symptom measurement
  • that reported major clinical depression only.

Applying exclusion criteria post hoc reduced the number of included studies and the analytical workload. We can’t tell whether it affected the study heterogeneity, because this wasn’t reported.

Data collection and analysis

The authors reported a selection of the data they extracted from the studies, which included baseline population characteristics, including cognitive scores and prevalence of BPSD, the study setting, and the number of participants. They also extracted data on the number and timing of the measurements taken, the measurement instruments used, covariates, statistical methods and study findings on prevalence, and the incidence and persistence of each symptom.

The findings were stratified by dementia severity (which was defined by baseline cognitive scores into no, mild, moderate, moderately severe, and severe dementia) and by individual BPSD symptoms.

Unfortunately this systematic review suffers from a number of important limitations.

Unfortunately this systematic review suffers from a number of important limitations.


From 5,923 identified articles, 48 studies were selected for inclusion. Eleven more studies were added after looking through the reference lists of the 48, giving a total of 59 studies. It would have been useful to include a PRISMA flow diagram with more detail on how the studies were selected. I would have been interested to know how many of the included studies were intervention studies, and whether they were studies of interventions for BPSD or for cognition. Surely this would have affected the interpretation of the persistence and incidence data?

The figures and tables reporting the results paint a bewildering and colourful picture of the variation in findings between the included studies and the valiant attempts of the reviewers to summarise and make sense of the data they extracted.

For example, the reported baseline prevalence of irritation in people with moderate dementia ranged between 25% and 90%. The persistence of affective symptoms such as depression and anxiety was reported by most of the studies to be low, yet one study reported it as high as 60%. The most consistent finding was that apathy had high baseline prevalence, persistence, and incidence, reportedly as high as 64% over two years.

As no quality assessment was done, there’s no way of selecting which individual study findings were most reliable. My personal view is that the real value of systematic reviews is to uncover the occasional gem of a study that is adequately powered, well conducted, and well reported, and pay more attention to its findings than the aggregated and homogenised findings of the whole review.

Influence of medication

My main concern about this review is that only fleeting reference is made to the influence of medications. If study participants had one or more BPSD symptoms, they were likely to have been treated with medication. For example, if they were aggressive, they could have been treated with an antipsychotic drug, which would have altered the natural course of the aggression symptom. Antipsychotic medication and many other drugs used to treat people with dementia can cause apathy. This could explain the observation that apathy was the most prevalent and persistent symptom. The authors stated that most of the studies that included a sensitivity analysis to account for medication use did not find altered results. However they didn’t report how many of the studies included a sensitivity analysis (it could have been 3, it could have been 50) or whether a majority meant 55% or 85%.

Apart from support for the theory that apathy might be an early sign of dementia, I wonder if this review achieves its aim of giving us a better understanding of the natural history of BPSD. It raises more questions for me than it provides answers or clarity, but it certainly succeeded in making me think.

This evidence raises more questions than it provides answers!

This evidence raises more questions than it provides answers!

Strengths and limitations

  • No protocol registered for this review
  • No quality assessment of the included studies, to assess risk of bias
  • The study eligibility criteria was narrowed post-hoc
  • Study heterogeneity was not reported, so we don’t know how similar the included studies were
  • The review included both observational and intervention studies, but they did not report how many of each were included in the final group of 59 studies, which makes it difficult to interpret this data.


Primary paper

van der Linde RM, Dening T, Stephan BCM, Prina AM, Evans E, Brayne C. (2016) Longitudinal course of behavioural and psychological symptoms of dementia: systematic review (PDF). British Journal of Psychiatry 1–12. doi: 10.1192/bjp.bp.114.148403 [PubMed abstract]

Other references

Data supplement (PDF) to van der Linde et al. (2016b) Longitudinal course of behavioural and psychological symptoms of dementia: systematic review. Br J Psychiatry doi: 10.1192/bjp.bp.114.148403

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