Obesity can trigger symptoms of Alzheimer’s disease and dementia, a new study has suggested.
Both obesity and Alzheimer’s were found to affect thin grey matter in the same ways – in the right temporo-parietal cortex and left prefrontal cortex.
As a result, scientists claim losing weight could slow cognitive decline and lower the risk of dementia.
Researchers from Montreal Neurological Institute-Hospital, McGill University, Quebec, suggested obesity and Alzheimer’s (AD) may cause the same type of neurodegeneration (the process by which nerve calls are irreversibly lost).
Obesity was previously linked with Alzheimer’s disease, but this is the first study to make a direct comparison between brain atrophy patterns in Alzheimer’s and obesity.
Like Alzheimer’s, obesity is associated with cerebrovascular damage affecting blood flow in the brain, and accumulation of amyloid-β, which prompts the degeneration of the brain.
“Our study strengthens previous literature pointing to obesity as a significant factor in Alzheimer’s disease by showing that cortical thinning might be one of the potential risk mechanisms," said the study’s author, Filip Morys, a PhD researcher at The Neuro, writing in the Journal of Alzheimer’s Disease.
“Our results highlight the importance of decreasing weight in obese and overweight individuals in mid-life, to decrease the subsequent risk of neurodegeneration and dementia.”
The scientists created a map of grey matter atrophy for Alzheimer’s sufferers, a healthy control group, those who were obese, and those who were not.
Grey matter atrophy was sampled in over 1,300 people and compared with Alzheimer’s sufferers and those who are obese.
What is dementia?
Dementia is a syndrome (a group of related symptoms) associated with an ongoing decline of brain function, according to the NHS. There are many different types, with many different causes, and it is not a natural part of ageing.
For example, Alzheimer's disease and vascular dementia are two different types, with both of them making up the majority of cases. Other types include frontotemporal dementia, dementia with Lewy bodies (DLB), young-onset, as well as mixed dementia (more than one at the same time).
The condition can affect memory, as well as the way you speak, think, feel and behave.
There are currently around 900,000 people with dementia in the UK, projected to rise to 1.6 million by 2040, according to the Alzheimer's Society. Some 209,600 will develop it this year, which is equivalent to one every three minutes.
The condition mainly affects older people, with the likelihood doubling every five years after the age of 65. However, it can affect younger people too.
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Alzheimer's disease is the most common cause of dementia in the UK. It is a progressive condition, meaning symptoms develop gradually over many years, slowly becoming more severe.
The exact cause isn't yet fully understood, though factors that can potentially increase your risk include age, a family history, untreated depression and lifestyle factors associated with cardiovascular disease.
The first sign is usually minor memory problems, such as forgetting about recent conversations or events, or forgetting the names of places and objects.
As the condition develops and symptoms become more severe, as listed by the NHS, these include:
Confusion, disorientation and getting lost in familiar places
Difficulty planning or making decisions
Problems with speech and language
Problems moving around without assistance or performing self-care tasks
Personality changes, such as becoming aggressive, demanding and suspicious of others
Hallucinations (seeing or hearing things that are not there) and delusions (believing things that are untrue)
Low mood or anxiety
Vascular dementia is a common type of the syndrome, caused by reduced blood flow to the brain, which often gets worse over time – though it's sometimes possible to sow it down. It can either start suddenly or begin slowly over time.
Symptoms listed by the NHS include:
Slowness of thought
Difficulty with planning and understanding
Problems with concentration
Changes to your mood, personality or behaviour
Feeling disoriented and confused
Difficulty walking and keeping balance
Symptoms of Alzheimer's disease, such as problems with memory and language (many people with vascular dementia also have Alzheimer's disease
This can make daily life increasingly hard for someone with the condition, eventually preventing them from being able to look after themselves.
Dementia with Lewy bodies (DLB)
DLB, also known as Lewy body dementia, is another common type of dementia. It is caused by the Lewy bodies, which are clumps of protein that appear in the nerve cells of the brain. As it shares symptoms with Alzheimer's disease and Parkinson's disease, it is often wrongly diagnosed.
Symptoms listed by the NHS include
Hallucinations – seeing, hearing or smelling things that are not there
Problems with understanding, thinking, memory and judgement – this is similar to Alzheimer's disease, although memory may be less affected in people with dementia with Lewy bodies
Confusion or sleepiness – this can change over minutes or hours
Slow movement, stiff limbs and tremors (uncontrollable shaking)
Disturbed sleep, often with violent movements and shouting out
Fainting spells, unsteadiness and falls
Generally speaking, frontotemporal dementia is an uncommon type of dementia. However, more specifically, while it occurs less in older people, it is the third most common type in people under the age of 65, according to Dementia UK.
It affects the front and sides of the brain, and causes problems with behaviour and language. Similar to other types of dementia, it usually develops slowly and gets gradually worse over a long period of time.
Symptoms listed by the NHS include:
Personality and behaviour changes – acting inappropriately or impulsively, appearing selfish or unsympathetic, neglecting personal hygiene, overeating, or loss of motivation
Language problems – speaking slowly, struggling to make the right sounds when saying a word, getting words in the wrong order, or using words incorrectly
Problems with mental abilities – getting distracted easily, struggling with planning and organisation
Memory problems – these only tend to occur later on, unlike more common forms of dementia, such as Alzheimer's disease
As well as mental symptoms, there may be physical ones too, such as slow or stiff movements, loss of bladder or bowel control, muscle weakness or difficulty swallowing. Frontotemporal dementia can also lead to someone being unable to care for themselves.
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Young-onset dementia is defined as someone who develops the condition before the age of 65 (the usual age of retirement) with more than 42,000 people living with it in the UK.
Younger people with dementia may also experience a wide range of symptoms, with the overall condition caused by a range of different diseases. However, the support they need might be different, because it might affect them different ways.
As listed by Alzheimer's Society, these include:
A wider range of diseases cause young-onset dementia.
A younger person is much more likely to have a rarer form of dementia.
Younger people with dementia are less likely to have memory loss as one of their first symptoms.
Young-onset dementia is more likely to cause problems with movement, walking, co-ordination or balance.
Young-onset dementia is more likely to be inherited (passed on through genes) – this affects up to 10% of younger people with dementia.
Many younger people with dementia don’t have any other serious or long-term health conditions.
Younger people living with dementia may also have concerns about how it will affect their family, relationships, finances, daily life, or the risk to future children.
When to see a GP
It's normal for memory to be affected by stress, tiredness, certain illnesses and medicine, but if you're becoming increasingly forgetful (or are experiencing other signs of dementia), particularly if you're over the age of 65, it's important to talk to a GP about it.
To distinguish normal memory loss from memory loss that could be a cause for concern, question whether it's affecting your daily life. If it's worrying you, or someone you know, don't delay in seeking advice.
Alzheimer’s Society is urging anyone worried about themselves or someone they love to take the first step and contact the charity for support. Support and more information about a diagnosis is just a phone call or a click away. Visit alzheimers.org.uk/memoryloss or call 0333 150 3456.
You can also use Alzheimer's Society's possible symptoms checklist to help with a medical appointment.
Additional reporting SWNS.