Elvina Ann Charly
Dementia is a group of symptoms that involve acquired and gradual impairments in cognition, memory, behaviour and emotion. Dementia is not an inevitable consequence of biological ageing, though ageing is the greatest risk factor for it. Conditions such as Alzheimer's come under the classifications of dementia, as per DSM-V. As dementia progresses, patients become increasingly dependent on others and need care in all aspects of daily living. Globally, the incidence rates for Dementia and Alzheimer’s are increasing at an exponential rate. Estimates show that 74.4 million people in 2030 and 131.5 million in 2050 will develop dementia, with the numbers doubling every 20 years (Prince et al., 2015, p.22). This is alarming as effective treatment is difficult after the early stages of the disease and infrastructure for care and management is insufficient.
Prevention thus becomes ever-important. Consequently, one of the seven principles of the World Health Organisation’s Global Action Plan calls for risk reduction practices for dementia that are evidence based (Global Action Plan, 2017). The 2017 Lancet Commission Report for Dementia Prevention, Intervention and Care considers dementia to be "the greatest global challenge for health and social care in the 21st century" (Livingston et al., 2017, p. 2673) and urges the world to be proactive and ambitious about taking preventative steps for dementia. In light of this, this paper seeks to present a brief overview of the various preventive measures that have been recommended and to understand to what extent they have protective capability against dementia.
According to the Lancet Commission report, risk factors for dementia can be of two types- modifiable and non-modifiable. The potentially modifiable risks account for 35% of the total risk for dementia and successful interventions for these could prevent or delay up to one-third of all dementia cases (Livingston et al., 2017). These risk factors have been grouped according to age or life stages. In early life, lower levels of education have been identified as a modifiable risk factor. As levels of education increase, cognitive reserve and resilience increases, which helps maintain cognitive health even in the presence of neuropathology. Promoting cognitive resilience to dementia through participation in intellectually stimulating activities has thus emerged as an important preventative measure. People in WEIRD countries and those of higher socio-economic status would be able to achieve this more easily, which is in line with the decreasing dementia rates in these countries.
In mid-life (45-65 years), the modifiable risk factors are hearing loss, hypertension and obesity. Hearing loss has been thought to negatively contribute to the cognitive processes of a brain already increasing in vulnerability with age. Vascular risk factors like hypertension and diabetes decrease amyloid clearing in the brain due to lowered insulin production. Thus, treatment of these conditions in mid-life helps lower the burden they pose to the brain. Late life sees ‘smoking, depression, physical inactivity, social isolation and diabetes’ (Livingston et al, 2017) as the greatest risk factors. Lot of these factors are ones that reinforce each other, like physical inactivity leading to obesity or diabetes. Therefore, multiple factors have to be kept in mind when going about risk reduction.
Exercise has been consistently recommended as a good protective factor against dementia. Exercise is a central modifier, implicated in the reduction of brain damage and inflammation along with increasing cognitive reserve (Livingston et al, 2017). A neuroprotective effect is seen with exercise, with an increase in and strengthening of synaptic connections, increase in hippocampal volume and greater release of brain-derived neurotrophic factors (BDNF) which supports neural health (Alty et al., 2019). Research supports that it is never too late to start exercising, as benefits from exercise show no threshold or ceiling. Aerobic exercise or cardio followed by resistance training show the strongest evidence in improving cognition. However, it is important to note that other factors may mediate this effect of exercise like ‘gender, ethnicity and comorbidities’ (Alty et al., 2019, p.5 ), into which more research needs to be done. Regardless, the benefits of exercise on cognitively healthy people and those with mild cognitive impairment provides hope in the face of the alarming dementia incidence.
Some research also points to low to moderate alcohol intake being correlated with a lower risk of dementia presentation. Interestingly, both complete alcohol abstinence and heavy alcohol intake were correlated with a higher risk of dementia presentation, though heavy alcohol intake proved far more disastrous for cognition. However, these discussions on alcohol are not conclusive (Rehm et al., 2019). Other interesting studies point to the protective effect of bilingualism (Bak et al., 2014) in preventing or delaying cognitive ageing. Early detection of Alzheimers is pertinent as these safeguards against Alzheimer's aren’t foolproof. Moreover, 65% of risk factors for dementia are non-modifiable (Livingston et al, 2017) which adds to the uncertainty in the preventative approach. People should be educated from the school level itself on how to detect early signs of Alzheimer's. Stigma reduction through awareness programs will further ensure that Alzheimer's suspected individuals are taken by their close ones to physicians or psychiatrists for consultation. Stigma has been found to be associated with underdiagnosis, with global estimates of over 75% (90% in low and middle income countries) undiagnosed dementia cases(Gauthier et.al, 2021). For example, fear of diagnosis from the part of the patient and family along with a mindset of hopelessness from the part of the clinician could lead to underdiagnoses (Gauthier et.al, 2021). While prevention matters, early detection and diagnosis should be advocated as well.
Though there is no sure way of controlling one’s neurocognitive fate, people should be urged to be aware of their level of risk to dementia and take up preventative care wherever possible. However, this doesn't mean that developing Alzheimer's is in any way the fault of the patient or that they didn't take enough preventative measures. Dementia is a multi-aetiological syndrome and causes can accurately be identified mostly only post mortem. Urgently, on a more public health scale approach, prevention can minimise the burden of care that the expected exponential rise in dementia cases would put on the healthcare system. Researchers should continue investigating the best risk reduction strategies for dementia.
Majority of studies that look at preventative measures have been done in WEIRD countries, with samples consisting of generally healthy and well-off male participants (Livingston et al., 2017). Thus, most recommendations for prevention and intervention made for a global audience become less applicable to low and middle income countries where the disease incidence rate is most alarming. In conclusion, dementia prevention research should be made country-specific and given more funding and resources in India, where incidence rates are among the most alarming. Parallely, individual prevention measures ought to be undertaken wherever possible, according to the unique genetic and environmental background of each individual.
References
Alty, J., Farrow, M., & Lawler, K. (2020). Exercise and dementia prevention. Practical neurology, 20(3), 234–240. https://doi.org/10.1136/practneurol-2019-002335
Bak, T. H., Nissan, J. J., Allerhand, M. M., & Deary, I. J. (2014). Does bilingualism influence cognitive ageing?. Annals of neurology, 75(6), 959–963. https://doi.org/10.1002/ana.24158
Gauthie,r S., Rosa-Neto, P., Morais, JA., & Webster C . 2021. World AlzheimerReport 2021: Journey through the diagnosis of dementia.London, England: Alzheimer’s Disease International. https://www.alzint.org/u/World-Alzheimer-Report-2021.pdf
Global action plan on the public health response to dementia 2017–2025. 2017. Geneva: World Health Organization. Licence: CC BY-NC-SA 3.0. https://www.who.int/publications/i/item/global-action-plan-on-the-public-health-response-to-dementia-2017---2025 . Last Accessed 12 December 2022.
Livingston, G., Sommerlad, A., Orgeta, V., Costafreda, S. G., Huntley, J., Ames, D., Ballard, C., Banerjee, S., Burns, A., Cohen-Mansfield, J., Cooper, C., Fox, N., Gitlin, L. N., Howard, R., Kales, H. C., Larson, E. B., Ritchie, K., Rockwood, K., Sampson, E. L., Samus, Q., … Mukadam, N. (2017). Dementia prevention, intervention, and care. Lancet (London, England), 390(10113), 2673–2734. https://doi.org/10.1016/S0140-6736(17)31363-6
Prince, M., Wimo, A., Guerchet, M., Ali, GC., Wu, YT., & Prina, M. 2015. World Alzheimer report 2015—the global impact of dementia: an analysis of prevalence, incidence, cost and trends. London: Alzheimer’s Disease International. https://www.alzint.org/u/WorldAlzheimerReport2015.pdf
Rehm, J., Hasan, O.S.M., Black, S.E. et al. Alcohol use and dementia: a systematic scoping review. Alz Res Therapy 11, 1 (2019). https://doi.org/10.1186/s13195-018-0453-0
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