Once the “most feared disease in the world”,¹ poliomyelitis (or polio) cases have declined by over 99% since the vaccination programme was launched globally in 1998.¹ Decades later, some survivors of the viral infection can develop post-polio syndrome (or PPS)² and suffer deterioration in physical and mental health – including the development of depression³. Let’s take a closer look.

A disease of the past³

Polio is a highly contagious viral disease, which affects mainly children under the age of 5.⁴ It affects the brain and nerves (particularly a group of cells called motor neurons which control the movement of our muscles) and is characterised by muscle weakness, fatigue and in extreme cases, paralysis.⁴ But this potentially life-threatening disease was virtually eradicated by the introduction of vaccines by Jonas Salk in 1955 and Albert Sabin in 1962.^1,4

It was once thought that recovery from the disease meant that the survivor would be healthy and stable going forward, requiring little to no additional medical support; but in the late 1970s, it became evident that people who had polio decades earlier were now experiencing deteriorating health.⁴ The presentation of symptoms such as muscle weakness, fatigue, and pain later in the patient’s life led to the classification of a new disorder in the 1980s, PPS.⁴

In the UK alone, “out of an estimated 120,000 people who have been previously affected by polio, up to 80% will develop post-polio syndrome (PPS)”.⁵ 

PPS – Key symptoms⁶ and characteristics⁷

PPS can develop gradually over many years, and it is associated with many symptoms that can collectively impact on physical and mental health, and overall quality of life.

Some of the common symptoms that occur in PPS, as outlined by the National Health Service (NHS)⁶, include:

• Fatigue: Excessive tiredness is a common feature of PPS. This fatigue can be general fatigue, physical muscle fatigue or mental fatigue
• Pain: Pain, particularly in joints (manifesting as soreness and stiffness) and muscles (spasms, cramps, and aches) is also common in PPS
• Muscle weakness: PPS can also lead to muscle weakness and even wasting away (or atrophy) of the muscle
• A gradual weakening of muscles can lead to a range of other symptoms, including:
  • Weight gain due to a reduction in physical activity – which can in turn exacerbate feelings of fatigue, pain and weakness
  • Mobility problems, including difficulty walking and the need for walking aids such as crutches or wheelchairs
  • Shortness of breath and other breathing difficulties such as sleep apnoea, as the muscles involved in the mechanism of breathing can weaken. There is also a heightened risk of chest infection 
  • Difficulties with chewing and swallowing (known as dysphagia), accompanied by choking or coughing sensations when consuming food or drink. Alterations in speech and voice may also occur such as hoarseness
  • Heightened sensitivity to cold is another feature apparent in PPS, due to poorer supplies of blood throughout the body
  • Fibromyalgia can mimic many of the symptoms of PPS⁸ such as pain, fatigue, sleep disturbance and muscle weakness

In one recent study,⁷ 400 patients attended an outpatient clinic in Barcelona, and 310 of these patients were diagnosed with PPS. Information was collected about their past (i.e. a retrospective study was carried out) and this shed light on other key aspects of PPS. For example, PPS occurs more frequently in women and begins at a mean age of 52.4 years (and earlier in women). Symptoms range in frequency, with pain being most common, followed by fatigue, tiredness and weakness, and depressive symptoms. Fatigue and depression occurred much more regularly in women. 

What is depression?

Depression is a common but serious and debilitating mental health condition, which can drastically impact a person’s ability to manage daily activities. Depression is also known as major depression, major depressive disorder (MDD) or clinical depression, and there are many different types and classifications in the gold standard manual for diagnosing mental health conditions – the DSM-5 (which stands for the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition). 

For a diagnosis of depression, a person must have symptoms for a minimum of 2 weeks and on nearly every day. These symptoms can include:⁸

• Persistent sadness, emptiness, hopelessness, or tearfulness
• Loss of interest or pleasure in activities 
• Changes to weight (weight loss or gain) or appetite (increased or decreased appetite)
• Changes in sleep (sleeping too much or too little or suffering from insomnia)
• Loss of energy or fatigue
• Feeling worthless or excessively or inappropriately guilty 
• Poor concentration or indecisiveness 
• And in severe cases, thoughts of death or suicide (known as suicidal ideation), or planning or attempting suicide

These symptoms are undoubtedly distressing for the individual experiencing them and those around them. Help and treatment are widely available through health services, from medication to psychotherapy.⁹

PPS and depression – what is the link?

People who have suffered and survived polio are typically at a greater risk of developing other ‘secondary’ conditions as well as a disability that can impair their health, well-being, level of independence and general quality of life.¹⁰ Re-experiencing symptoms of polio through PPS much later in life can reawaken painful memories from the past – whether of the physical symptoms of the disease itself, or the feelings of stress, distress, and vulnerability, or experiences of mistreatment.¹¹  

To date, very few studies have investigated depression in people who develop PPS. Early research into the links between PPS and mental health have shown there is some relationship between PPS and depression,¹¹ with higher rates of depression in individuals diagnosed with PPS.^3,10 In one study, 8 out of 15 patients (53%) assessed for PPS were found to have depression;¹² and this evidence base was strengthened in another larger study of over 2000 polio survivors.¹⁰

However, the overlap in symptoms and patient experience between PPS and depression are apparent,¹³ from fatigue and sleep disturbance to weight gain. In a medical setting, one can be overlooked for the other, for instance, PPS can be interpreted as depression. It can alternatively be seen as just a natural part of the ageing process.¹³ Evidence does not yet fully clarify the causal relationship and the prevalence of depression in PPS patients varies by a wide array of other factors. For example:

• Co-morbid physical or psychological conditions 
• Attitudes of the individual and those around them to disability
• Levels of support received
• Social factors, such as social activity, loneliness or isolation
• Levels of childhood trauma (PPS patients who experienced severe childhood polio would have been removed from their families and even hospitalized for potentially years on end, a trauma which may have been long-lasting into adulthood)

Although the evidence base is variable as to the extent to which depression occurs in polio survivors, gradually deteriorating health, function and ability, and restrictions to carrying out normal daily activities – as seen in both disease states - has substantial psychological impact.¹³

Support for those with PPS and depression

A ‘patient-strengths perspective’ should be adopted to better support this cohort.³ But what does this mean in practice? Given the complex overlap and interplay of PPS with other conditions including depression, what is clear is that medical practitioners must consider all aspects of the individual’s medical history and background to build a clear picture of their underlying symptoms, particularly around pain and fatigue, as well as their life experiences.¹³ Healthcare providers should also consider the hesitation of individuals to re-engage with healthcare settings, if past experiences were challenging and traumatic.¹³

Evidence also suggests that helping those ageing with PPS to build psychological resilience could prevent or reduce depressive symptoms.³ Resilience can mean many things – from having good coping behaviours such as problem-solving or engaging with networks of support (family, friends), to demonstrating certain character traits (like flexibility or acceptance) and managing sudden change or life stressors well.³ Evidence in PPS patients demonstrates that using these mechanisms to build psychological resilience can lessen depression and this is achieved by ‘fostering feelings of hope, self-reliance, and optimism’.³

Counselling techniques to build resilience can be beneficial to help with managing the stress and psychological aspects of PPS and the accompanying gradual decline in health. Collaborative work to discover patient strengths, their own perceptions of health and the future, and their willingness to engage to build a tailored care plan should be encouraged in future practice.³

One 2020 study looked at a self-management programme for PPS, the only one available in the United Kingdom at the time, in which patients complete a multi-disciplinary clinical team-led residential programme.¹⁴ Self-management groups have been established for other chronic conditions, such as chronic pain, with benefits seen to quality of life. It was found that tailoring self-management programmes for PPS can considerably improve well-being and physical function, including reducing fatigue levels. However, further research is needed to look at depressive symptoms more specifically over time. 

Summary

PPS is where the symptoms of an initial polio infection can reappear or worsen decades after the original infection in polio survivors. The fatigue, muscle weakness, and pain, as well as the reviving of thoughts, feelings and memories of past illness, can lead to psychological distress and depression. PPS and its link to depression is poorly understood and it is necessary to proceed with caution when interpreting the literature and assessing these patients. But with continued research and understanding, and earlier care and support, more hope and encouragement can be given to those who suffer from these crippling conditions that can strike unexpectedly later in life.