Lost in the Present

Amnesia and its most common causes

Our brains are always sorting, storing and retrieving information. It’s a busy job, and it’s normal for things to fall through the cracks. But not all memory loss is normal. Sometimes, memory loss can be linked to specific causes and even be a sign of a bigger problem. Having said that, anything that impacts thinking, learning or remembering can impact memory – and that’s a long list. Here are some of the most common causes of memory loss.


Prescription drugs like benzodiazepines and anticonvulsants are linked to memory disorders. Other drugs, such as serotonin reuptake inhibitor antidepressants, newer anticonvulsants, isotretinoin and ciclosporin, are also significantly associated with memory loss.

Head injury

Head trauma like concussion can lead to memory loss. A single blow to the head can cause memory loss that either stays the same or improves over time. Meanwhile, repeated blows to the head – like those from boxing or football – can cause progressive memory loss and other cognitive problems.

Thyroid issues

In hypothyroidism, the thyroid gland doesn’t produce enough thyroid hormone. On the other hand, hyperthyroidism happens when the gland produces too much thyroid hormone. This hormone controls the way cells use energy, and when these levels are off, short-term memory loss can occur. If treated early, this memory loss may be reversible.

Lack of sleep

Sleep deprivation can lead to reduced memory, and sleep apnea may promote memory loss. A recent study of almost 8,000 people found people who slept less than six hours a night in their 50s, 60s and 70s had a 30 per cent higher risk of dementia than their peers who slept more. This finding proved true across factors like demographics, behaviours and mental health.

Nutritional deficiencies

Not enough vitamin B1 or B12 can lead to memory loss. B1, also called thiamin, is key to the growth, development and function of cells. Vitamin B1 deficiency can be linked to alcohol dependence, HIV/AIDS and some medications. Meanwhile, vitamin B12 helps keep blood and nerve cells healthy. As we age, our levels of vitamin B12 decline naturally.

Cancer treatment

About 70 per cent of people who have cancer report cognitive problems, and about a third of people still have issues following treatment. While “chemo brain” is a common term used to describe the mental fog that can accompany chemotherapy, other treatments can impact memory, too, such as radiation therapy, brain surgery and medications like hormone therapy or immunotherapy.


Both short- and long-term memory loss are common in older stroke survivors. Over time, memory may improve, either on its own or through rehabilitation. But symptoms can last for years and be made worse by some medications, lack of sleep and use of alcohol or drugs. Medications for related issues like anxiety, depression or sleep disorders may help address memory loss after stroke.

Mental health issues

Major, traumatic events can lead to memory loss, and difficulty concentrating and remembering can be a symptom of both anxiety and depression, especially in older people. These issues can also be problems for people with bipolar disorder. And while schizophrenia often causes hallucinations and delusions, it can also cause problems with short- and long-term memory. Researchers have identified a biomarker that will help them better understand and treat these memory deficits.