Alzheimer’s disease (AD) is a progressive neurodegenerative disease which is present for decades before a clinical diagnosis of dementia is typically made1. Earlier on this pathological pathway is mild cognitive impairment (MCI) characterised by objective changes in memory and cognition without the presence of dementia or significant changes to activities of daily living2. Much research has focused on MCI as part of a pre-AD stage, however, not everyone with MCI will go on to develop dementia. Unfortunately, irreversible neuronal damage will have already occurred by the time someone develops MCI1. Therefore, it is important for research to focus on the earlier pre-clinical stage of subjective cognitive decline (SCD) where cognitive functioning is relatively intact. SCD is commonly prevalent when individuals express concerns about cognitive difficulties, which are unidentifiable on standardised cognitive measures.
Research suggests that people with SCD are 4.5 times more likely to develop MCI than people without. This implies that SCD could be a pre-MCI stage, and therefore possibly a harbinger to AD3. For some people, subjective changes to for instance, memory and thinking skills, may become a natural response to ageing, often considered as ‘senior moments’4. However, research has shown that SCD, irrespective of its aetiology, can have a significant detrimental impact on mental health, including well-being, loneliness, depression, and anxiety and therefore should not be considered benign3,5. Lastly, early diagnosis of dementia and cognitive impairment, is crucial, not only to potentially slow down progression from a point of greater preserved cognitive functioning, but also to prescribe medication at the stage it is believed to have the most benefit.
Memory clinics throughout the UK have many different care pathways for people experiencing cognitive changes, especially those experiencing early changes6. For instance, some clinics offer a comprehensive assessment and prevention-training programme, whilst others discharge patients and advise them to return if symptoms worsen, which can cause fear of impending dementia. Unfortunately, there is very little consensus regarding how SCD should be assessed and managed. Insufficient management can lead to a lack of a timely diagnosis of dementia and possible modifiable risk factors, such as depression and anxiety, and not gaining treatment in a timely manner. There are many factors which lead to this heterogeneity in care including lack of resources (e.g. staff) needed to fully investigate patients’ historical and potential diagnosis of SCD and a lack of awareness of subjective cognitive decline amongst clinicians 6.
Evidently, it is imperative for dementia to be identified earlier, however, there will likely be a resource capacity vs demand issue due to the foreseeable increase in cognitive assessment referrals. This coupled with our ageing society and the impact of COVID-19 may result in a high demand for services. Past research suggests that dementia care pathway transformations could benefit from considering the following6:
References
1 Jack Jr, C.R., Knopman, D.S., Jagust, W.J., et al (2013). Tracking pathophysiological processes in Alzheimer’s disease: an updated hypothetical model of dynamic biomarkers. Lancet Neurology, 12, pp.207–216.
2 Petersen, R.C. (2004). Mild cognitive impairment as a diagnostic entity. Journal of Internal Medicine, 256(3), pp.183-94.
3 Reisberg, B., Shulman, M.B., Torossian, C., Leng, L., and Zhu, W. (2010). Outcome over seven years of healthy adults with and without subjective cognitive impairment. Alzheimer’s and Dementia, 6, pp. 11–24.
4 Desai, A.K., and Schwarz, L. (2011). Subjective cognitive impairment: When to be concerned about ‘senior moments’. Current Psychiatry, 10(4), pp. 31-45.
5 Jessen et al (2014). A conceptual framework for research on subjective cognitive decline in preclinical Alzheimer’s disease. Alzheimer’s and Dementia, 1-9.
6 Jenkins, A., Tales, A., Tree, J., and Bayer, A. (2015). Are We Ready? The Construct of Subjective Cognitive Impairment and its Utilization in Clinical Practice: A Preliminary UK-Based Service Evaluation. Journal of Alzheimer's Disease; 48(s1): S25-S31. DOI:10.3233/JAD-150541