5 min readAug 1, 2024 02:17 AM IST
First published on: Jul 31, 2024 at 07:08 AM IST
Now you have another reason to watch your cholesterol. A new Lancet Commission report has flagged it along with untreated vision loss as significant new risk factors for dementia, a condition characterised by memory problems and disruptions in thinking and social skills. Its most prevalent form is Alzheimer’s Disease, which accounts for about 60-70 per cent of dementia cases.
In fact, both these factors have been found to be a trigger for nine per cent of all dementia cases. Seven per cent of cases can be linked to high levels of low-density lipoprotein (LDL), commonly known as bad cholesterol, which develops midlife around age 40. Two per cent of dementia cases are linked to untreated vision loss in later life.
WHY IS THE STUDY IMPORTANT
The report, authored by 27 leading dementia experts, highlights the crucial importance of managing cholesterol levels and addressing vision issues to potentially reduce the risk of developing dementia. The World Health Organization (WHO) ranks dementia as the seventh leading cause of death globally. Suvarna Alladi, professor of neurology at the National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, and among the key authors, says the new findings are significant for India as the prevalence of dementia for people older than 60 years is 7.4 per cent with an estimated 8.8 million living with dementia. “Age is the strongest and best-known risk factor for dementia. The new evidence shows why screening for and treating vision loss and managing cholesterol levels should now be prioritised in older adults to potentially reduce the incidence of dementia,” she explains.
Back in 2020, the Lancet Commission had identified 12 risk factors for dementia: lower levels of education, hearing impairment, high blood pressure, smoking, obesity, depression, physical inactivity, diabetes, excessive alcohol consumption, traumatic brain injury [TBI], air pollution and social isolation.
What can you do to prevent dementia?
ROLE OF BAD CHOLESTEROL
A meta-analysis of three UK studies with over 1.1 million participants under 65 showed that each 1 mmol/L increase in LDL cholesterol raised dementia risk by eight per cent. Another study with 1.2 million participants found that having LDL cholesterol over 3 mmol/L increased dementia risk by 33 per cent. Additionally, a large UK study of 1.8 million people followed for 7.4 years confirmed that higher LDL cholesterol levels were associated with a greater risk of dementia.
Researchers explain that the link between bad cholesterol and dementia stems from excess cholesterol raising stroke risk and triggering the buildup of two proteins —amyloid β and tau — that disrupt functioning of brain cells.
High levels of LDL cholesterol have been associated with greater amyloid burden in the brain. “Several mechanisms that explain the link between high LDL cholesterol (levels more than 100mg/dl) and brain amyloid deposition include the increased activity of amyloid-producing enzymes like secretases, decreased clearance of amyloid from the brain, adverse effects on neuron cells and damage to the blood brain barrier via inflammatory mechanisms,” says Dr Faheem Arshad, assistant professor of neurology, NIMHANS.
That’s why the researchers emphasise that “individual counselling about diet and exercise has a small effect in reducing LDL cholesterol. Statins have become a focus of research in the field of Alzheimer’s disease and have potential benefits due to their anti-inflammatory and antioxidant properties besides reducing cholesterol.”
DON’T IGNORE VISION LOSS
So what’s the link between dementia and untreated vision loss? The study says that the mechanism could be related to illnesses such as diabetes, which is a known risk factor for dementia. Additionally, there could be an underlying problem, affecting both the retina of the eye and brain.
Dr Arshad feels that correcting vision issues, like refractive errors, can slow down cognitive decline by improving sensory inputs. “This is a bidirectional relationship as cognitive factors influence visual processing. Regions of the brain involved in memory and semantics impact how we perceive and interpret visual information. So sensory deprivation can accelerate cognitive decline. Age-related sensory impairments are complex and involve both biological and environmental factors,” he says.
Dr Arshad explains that both cognitive and sensory dysfunctions are triggered by ageing, external factors (alcohol, smoking), neurodegenerative disorders, and biological factors. “Sensory and cognitive impairments are interrelated, with each affecting the other in various ways. Addressing these issues requires a comprehensive approach that considers their complex interplay,” he adds.
![Back in 2020, the Lancet Commission had identified 12 risk factors for dementia: lower levels of education, hearing impairment, high blood pressure, smoking, obesity, depression, physical inactivity, diabetes, excessive alcohol consumption, traumatic brain injury [TBI], air pollution and social isolation.](https://images.indianexpress.com/2024/07/Untitled-design-20-6.jpg?w=1600)
Back in 2020, the Lancet Commission had identified 12 risk factors for dementia: lower levels of education, hearing impairment, high blood pressure, smoking, obesity, depression, physical inactivity, diabetes, excessive alcohol consumption, traumatic brain injury [TBI], air pollution and social isolation. 
What can you do to prevent dementia?
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