By Ann Marie Gaudon, PNN Columnist

Pain is a complex experience. It not only affects us biologically, but we also experience it cognitively and emotionally. Does it affect our memory? You bet it does.

Chronic pain patients often complain of memory problems and there are numerous studies which confirm these challenges are indeed a reality.

Twenty-four studies evaluating working memory (WM) and/or long-term memory (LTM) in chronic pain groups and control groups were reviewed last year by French researchers. WM was defined as the processing and manipulation of information within a short period of time (a few seconds), while LTM involved the “storage” of knowledge and memories over a long period of time.

Concentration and memory deficits on a daily basis were the most frequently reported cognitive difficulties. Memory complaints included forgetfulness and problems performing everyday tasks and conversations.

Emotional distress common to pain patients, such as depression, anxiety and rumination (the inability to divert attention away from pain), was also found to play an important role in memory difficulties.

One study compared two groups of pain patients who had minor or major memory complaints. Between the two, no significant differences were found with regard to age, gender, education level, marital status, medication use, long-term pain or pain intensity.

However, patients in the major memory complaint group suffered from emotional distress to a significantly greater degree. They also reported a lack of family support and discontent with their social and sexual lives. These were noted as additional daily sources of suffering for this group.

Adding to potential negative effects on memory were comorbidities which many pain syndromes share. Conditions such as depression, anxiety, sleep disturbances, and chronic fatigue could alone or combined affect memory. A major concern expressed was the need to disentangle pain-related cognitive effects from those resulting from these comorbidities.

Medications and Memory

The review really became interesting when it came to medication, because researchers found contradictory results. One European study reported that opioids exerted a negative effect on working memory -- finding a clear association between higher levels of analgesics and perceived memory dysfunction in chronic back pain patients. Some studies confirmed that medication can have a negative effect on memory, but others showed improvements in memory following analgesic treatment. That suggests that effective pain relief may also reverse pain-induced memory impairment.

The researchers concluded it was unclear whether analgesic medications are beneficial or detrimental, because both scenarios were reported.

Age was also identified as an important factor in the relationship between chronic pain and memory, but not in the way you may think. Surprisingly, it was shown that an increase in age did not additionally affect memory performance.

One study reported that gender and age significantly affected memory decline in those suffering from chronic migraine headaches. Cognitive decline in migraineurs was greater among younger individuals, and females showed greater decline during headache intervals than males. It was acknowledged that gender as a factor in pain-related experience is poorly investigated.

Like all reviews, this one has its limitations. There was a “large heterogeneity” of tests within the 24 studies. This diversity of tests did not allow for a suggestion of which memory processes were altered by chronic pain itself. The study populations were also heterogeneous regarding pain etiologies and an assessment of the intensity of pain was not performed.

Studies which included a mix of chronic pain disorders did not provide data on whether specific memory impairments were more frequently observed in specific disorders. The authors suggest there is a need for comparative studies across pain-related disorders in order to determine whether impairments are pain-related or a consequence of other pathophysiological features.

These numerous studies confirmed the memory decline that is often reported by chronic pain patients. Even if these effects are mild, the impact on quality of life could be substantial as they may indeed worsen suffering including depression, anxiety, and limitations on activity.

Researchers suggested that examining memory function should be part of the clinical assessment of chronic pain patients. The spectrum of cognitive difficulties must become acknowledged and understood in order to find ways to overcome them.

Ann Marie Gaudon is a registered social worker and psychotherapist in the Waterloo region of Ontario, Canada with a specialty in chronic pain management.  She has been a chronic pain patient for over 30 years and works part-time as her health allows. For more information about Ann Marie's counseling services, visit her website.

The information in this column should not be considered as professional medical advice, diagnosis or treatment. It is for informational purposes only and represents the author’s opinions alone. It does not inherently express or reflect the views, opinions and/or positions of Pain News Network.