Forgetfulness isn’t always a sign of dementia. Experts explain how vitamin deficiencies, thyroid problems, medication side effects, depression and infections can all affect memory.
Misplacing keys, forgetting names and mixing up appointments are just some of the everyday symptoms that make us worry we might be losing the plot.
“You may be concerned they are the first signs of dementia, but be reassured there are many other underlying – and treatable – causes,” says Emma Taylor, at Alzheimer’s Research UK.
“Unfortunately, some people do get misdiagnosed with dementia when their memory symptoms might have another cause, such as a vitamin deficiency, a thyroid condition, an infection, stress or depression, as there is no perfect test for dementia and sometimes an overlap in symptoms.”
It can be a jigsaw puzzle to work it out, says Dr Patrick Hogan, co-chair of the British Geriatrics Society’s dementia, delirium and brain health special-interest group. “We’ll do blood tests for thyroid disease and vitamin B12 deficiencies, review the medications you’re on and take your history – this is how we put the pieces together.”
Both experts stress that if you’re worried, it’s important to see your GP who can order tests to diagnose these common conditions, plus a memory test if necessary.
An estimated 10 to 15% of people over 60 are deficient in vitamin B12, which is key for brain health. Symptoms include memory problems, difficulties with understanding and judgement, pins and needles, lack of energy and muscle weakness.
“Vitamin B12 helps to make the protective coating around the nerves that aids them in communicating,” says Taylor. “When levels are low, the nerve fibres, particularly those in the brain and spinal cord, can become damaged and communication slows down.
“If B12 deficiency remains untreated it can lead to high levels of homocysteine, which can be toxic to nerve cells and blood vessels. This can disrupt nerve signalling, affect attention, processing speed and memory, and can reach a stage where it is not reversible, which is why early diagnosis and treatment is so important.”
The most common cause of B12 deficiency in older people is pernicious anaemia, where the immune system attacks healthy cells in the lining of the stomach, preventing the vitamin being absorbed. Other causes include dietary deficiencies (B12 is found in meat, eggs, dairy and fish) and side effects of prescription medicines, including proton pump inhibitors or PPIs (such as omeprazole), commonly prescribed for acid reflux.
Hypothyroidism, where the thyroid gland doesn’t make enough of the hormone thyroxine, can also affect memory. It’s very common in people over 60 and the chance of developing it rises the older you get. Up to one in four people in nursing homes have undiagnosed hypothyroidism.
“Thyroid function is really important for ensuring that all the chemical messages in the brain are working properly,” says Taylor.
“Lower levels of thyroxine [hypothyroidism] cause less blood flow to the brain and slow down neural firing. This affects the synapses [communication junctions] between nerve cells and means the brain will run more slowly. It will affect things like information processing, retrieval of memories, attention and mood. Depression is quite a common symptom.”
Other symptoms include weight gain, fatigue, sleepiness, dry skin, and constipation. The British Thyroid Foundation says diagnosis and treatment of older people with thyroid disease is not always easy, as symptoms are not as obvious as they are in younger people. Cognitive decline, for instance, is often put down to getting older, yet may be the only hypothyroidism symptom that a person has.
Depression affects an estimated 22% of men and 28% of women aged 65 and over in the UK, and some people with depression will have memory symptoms as part of their condition, says Dr Hogan.
“A person’s awareness of their symptoms can sometimes provide clues,” he explains. “Some people with depression-related cognitive symptoms are very aware of their difficulties and may be able to describe them in detail, while people with dementia often have reduced insight into the extent of their memory problems.
“It’s sometimes more complicated than this, though, as people with dementia can have depression and low mood too.”
Dr Hogan says a physician would be looking for other symptoms of depression and cognitive problems to try to differentiate between the two.
Two thirds of people aged 65-plus take five or more prescription drugs, and more than 765,000 people in England take ten or more different pills or medicines.
“Medications are a huge part of the story here,” says Dr Hogan. “The key drugs we usually look at are a group called anticholinergics, the classic example of medicines that can affect memory and thinking, particularly in older people.
“They are not the only medicines that can do this, but they are important. Common examples include some drugs prescribed for overactive bladder, including tolterodine, oxybutynin and solifenacin.”
Dr Hogan says benzodiazepine drugs prescribed for sleep problems, as well as some types of antihistamines and antidepressants, can also affect memory. If you are concerned about medication side effects, ask your GP or pharmacist for a medication review.
Any type of infection can trigger delirium, a sudden confused state that can cause hallucinations, paranoia and an unsteady gait.
“These will normally come on within hours and days,” says Dr Hogan. “Delirium can cause changes in arousal – either a hypoactive state where someone is drowsy and difficult to rouse, or hyperactive where they become agitated and aggressive.”
By contrast, people with dementia will typically have a normal level of arousal.
“One in three over-65s admitted to hospital may experience it during their stay,” Dr Hogan points out. “Anyone of any age can develop delirium, but it’s more common in older people, particularly those who have dementia, or who have had surgery or been in intensive care.”
Although it can be triggered by an infection, such as a urinary tract or chest infection, delirium can also be caused by surgery, dehydration, severe constipation, injuries, drug side-effects, and severe psychological stress.
“Delirium is treated by finding the cause – such as an infection – and treating it,” Dr Hogan explains. “There may be more than one cause. In most cases, the symptoms are reversible, although in some cases they are not. Delirium also increases your chances of developing dementia at a later stage.”
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