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Five common causes of forgetfulness

Patsy Westcott / 29 July 2020

Getting a bit absent-minded? Don’t worry, it doesn’t mean you’ve got dementia - here’s our guide to the top five reasons for becoming forgetful.

Sources of Vitamin B12
Vitamin B12 plays a vital role in maintaining the brain and nervous system. It’s found in meat, poultry, eggs and milk.

Trouble remembering phone numbers? Dither over simple decisions? Problems following recipes? You’re not alone – particularly if you’re over 50. And with the constant flow of stories about Alzheimer’s disease and dementia in the press and online, it’s not surprising that such mental slips raise the question, ‘Could it be dementia?’ 

Well, the good news is that such everyday trials are often caused by other, often treatable problems. These include depression, a physical illness such as a urinary infection, poor eyesight or hearing, vitamin deficiencies or thyroid problems, rather than cognitive impairment.

Dementia is far more than ordinary forgetfulness or occasional foggy thinking, says Professor June Andrews, advisor to the Dementia Services Development Trust. ‘You need to start worrying only if you experience a significant, progressive downturn in your mental capacity,’ she says. ‘It’s normal to misremember phone numbers, for instance, but not to forget how to use your mobile or what it’s for.’

If you are worried about your symptoms see the doctor and get them checked out. Here are some of the more common problems that could fool you into thinking you're developing dementia.

1. Vitamin B12 deficiency

Dementia-like symptoms include: poor judgment and low mood.

Vitamin B12 plays a vital role in maintaining the brain and nervous system. It’s found in meat, poultry, eggs and milk. But age-related changes in stomach acid, certain medications (including proton pump inhibitors used to treat reflux, antibiotics, metformin used to treat Type-2 diabetes) and excess alcohol can all deplete the body’s stores. 

Left untreated, a vitamin B12 deficiency can lead to brain shrinkage and symptoms such as confusion, apathy, depression, poor memory and judgment. Other problems, though, can include numbness, pins and needles, disturbed vision and unsteadiness on your feet. 

Next steps

Ask your doctor for a blood test. They may suggest vitamin B12 injections if you are short of this vitamin. An Oxford University study found that taking a combination of vitamin B12 (0.5mg/day), plus folic acid (0.8mg/day) and vitamin B6 (20mg/day) for two years significantly slowed brain shrinkage in those with mild cognitive decline.

Need to talk to a GP from the comfort of your own home? Saga Health Insurance customers can talk to a qualified, practising UK GP 24 hours a day by phone. Find out more about our GP service.

2. Depression

Dementia-like symptoms include: poor concentration and apathy. 

At least one in five people will experience depression at some point in life and more than one in five people over 65, according to figures from Age UK. (The figures also show women are more prone to depression than men.)

Depression can be linked with cognitive problems. It is, for example, more common in people with dementia, particularly if they have vascular dementia or Parkinson’s disease dementia. And depression is often diagnosed when a person is in the early stages of dementia. in two out of five older people So how can you tell the difference?

For a start depression tends to come on quicker than most types of dementia – meaning over weeks or a few months rather than years. People with dementia meanwhile often have problems with their speech as well as with working out where they are or what time it is, a feature that isn’t common in depression.

Problems with memory are also a common feature of both depression and dementia. But while someone who is depressed may have difficulty remembering something they usually do recall that if prompted. Someone with dementia on the other hand, especially Alzheimer’s disease, may not remember recent events even when prompted and they may try to hide this.

Finally while someone with severe depression may have problems with reasoning or memory this is usually due to poor focus. Once the depression is treated they return to normal – unlike someone with dementia.

While someone who is depressed may meet an acquaintance and forget their name, they will know who they are. Someone with dementia, on the other hand, will be unable to identify the person behind the name.

People with depression can also experience what doctors call ‘delayed verbal recall’, a problem remembering words, and may speak more slowly. With dementia, though, this goes further. Sufferers frequently forget words for common objects. For example, they may describe a cup as “that thing you put tea into”.

Next steps

Again, you should see your GP – depression is, of course, a real illness that can be treated successfully. 

Antidepressants, exercise, reminiscence therapy and advice on stress-management are all options. And in a recent review in the International Journal of Geriatric Psychiatry, cognitive behavioural therapy was reported to help improve planning and problem-solving skills, as well as lifting mood, in older people with depression and cognition problems.

3. Urinary tract infection (UTI)

Dementia-like symptoms include: hallucinations and restlessness

For many, this common bacterial infection can bring on a fever, create an urgent need to pee or make it uncomfortable to do so. But older sufferers – whose immune systems may no longer respond to such infections, who may have less sensitive pain receptors and could already have problems going to the loo – may not notice anything unusual. 

Apart, that is, from sudden confusion known as delirium, which can happen in older people with a UTI as well as someone with dementia. Often a result of the dehydration a UTI causes, its effects include lack of awareness of surroundings, inability to follow a conversation or speak clearly, vivid, scary dreams, seeing people or things that aren’t there, restlessness, wandering, slowness and mood changes. 

‘What distinguishes these problems from dementia,’ says Dr Trisha Macnair, specialty doctor in medicine for the elderly with Surrey Community Health, ‘is that they tend to come on quickly [hours, days or weeks], rather than developing over years.’

Other UTI symptoms to look out for include cloudy, unpleasant-smelling urine, a general feeling of being unwell or nausea. Our thirst-sensation is blunted with age, so guard against dehydration in general by drinking plenty of fluids. 

Note: a UTI could speed up the progression of dementia - which is why all infections should be identified and treated promptly.

Next steps

A course of antibiotics, drinking lots of water, a healthy diet and rest usually bring fast relief. 

Cranberry tablets (which contain compounds thought to stop bacteria sticking to the urinary tract’s walls) or probiotics may help keep UTIs at bay if you’re prone to them. Meanwhile a pre-biotic called D-Mannose has been found to be an effective aid in acute cystitis management as well as helping prevent cystitis in several early studies. More research is needed but watch this space.

4. Thyroid problem

Dementia-like symptoms include: failing memory and fatigue

The thyroid, a small butterfly-shaped gland in your neck, produces hormones that regulate most bodily functions, including mood and cognition. And, like dementia, symptoms of thyroid problems can creep up relatively slowly.

An underactive thyroid is more common in women and is estimated to affect one in 20 people aged 60-plus. 

Difficulty thinking, poor working memory (the kind used to follow the steps in an instruction manual), slowed reactions and low mood are some clues. Other tell-tale signs that may distinguish it from dementia, however, include weight gain, over-sensitivity to cold, dry skin, hair loss and constipation.

An overactive thyroid can trigger poor attention, concentration and memory for words, anxiety, restlessness, palpitations, over-sensitivity to heat and weight loss. 

Next steps

A simple blood test can identify if your thyroid is pumping out too few or too many hormones. Medication usually sorts things out within weeks. Occasionally, other treatment, including surgery, may be needed for an overactive thyroid.

Always tired? Find out why

5. Medication overload

Dementia-like symptoms include: confusion.

Getting older invariably means taking an increasing number of medicines and, when they’re combined, they can cause cognitive symptoms that resemble long-term mental issues. 

Some drugs cause problems by themselves. ‘Anticholinergics – prescribed to treat asthma, incontinence, insomnia, gastrointestinal problems, muscle spasms and high blood pressure – may cause confusion by blocking acetylcholine, a brain messenger chemical involved in memory and learning,’ says Dr Warner. Feeling light-headed, having a dry mouth, constipation, bladder problems or blurred vision are other possible side effects.

‘Sleeping pills and “opiate” painkillers for conditions such as arthritis and back pain can also damage alertness,’ he adds.

Next steps

Always take medications exactly as prescribed. Gen up on side effects and possible cross-reactions by reading in-pack instructions for prescription and over-the-counter medications, including herbal and dietary supplements. 

If you’re uncertain, check with your GP or pharmacist. Make sure medications are reviewed regularly to check they are still appropriate for your needs.

A guide to understanding drug interactions

Professor June Andrews is the author of Dementia: The One-Stop Guide. Practical advice for families, professionals, and people living with dementia and Alzheimer’s disease. (Profile Books, £9.99)


Need to talk to a GP from the comfort of your own home? Saga Health Insurance customers can talk to a qualified, practising UK GP 24 hours a day by phone. Find out more about our GP service.


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