In 2021 it was estimated that over 7.5 million US adults have psoriasis, making it one of the most common immune-mediated diseases affecting US adults.
Psoriasis is a chronic, inflammatory skin disease marked by red, scaly plaques commonly found on the scalp, elbows, knees, and lower back. It has no cure and is characterized by cycles of flare-ups and remissions.
Psoriasis can present in various forms, such as plaque, guttate, pustular, and erythrodermic, and may also affect the joints (psoriatic arthritis), nails and eyes. Managing psoriasis typically requires an interprofessional healthcare team and includes topical treatments, systemic medications, and lifestyle modifications.
Inside this article we’ll outline the causes and risk factors associated with psoriasis, empowering patients to better understand their condition and manage it proactively to reduce the suffering that happens with regular psoriasis flare-ups.
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What is Psoriasis?
The pathogenesis of psoriasis involves a dysregulated immune response due to genetic, environmental, and immune-related causes.
Understanding Psoriasis
Psoriasis is a chronic skin disease characterized by the overproduction of skin cells due to an autoimmune inflammatory response. It results from a combination of genetic, environmental, and immune factors that trigger inflammation, leading to thick, scaly skin.
The psoriasis cycle starts when risk factors like injury, infection, certain medications, hormonal imbalances, alcohol, smoking, or stress activate an immune response in the skin. Immune cells then trigger inflammation, releasing molecules such as interferon, TNF-alpha, and interleukins which amplify the immune reaction, similar to a snowball gaining size and speed as it rolls downhill.
This increased inflammation overstimulates keratinocytes (skin cells), causing them to multiply quickly and form the thick, scaly patches typical of psoriasis.
Types of Psoriasis
- Plaque psoriasis (PP): also known as psoriasis vulgaris, this is the most common form of psoriasis. PP is characterized by raised, red patches covered with silvery-white scales typically on the elbows, knees, scalp, and lower back.
- Guttate psoriasis: small, drop-shaped lesions that appear on the trunk, arms, or legs, often triggered by a bacterial infection like strep throat.
- Inverse psoriasis (IP): smooth, inflamed patches that occur in skin folds, such as under the breasts, in the armpits, or around the groin and buttocks. IP typically lacks the white scales seen in other psoriasis forms.
- Pustular psoriasis: a rare form of psoriasis with clearly defined, pus-filled blisters surrounded by red skin, which can occur in widespread patches or smaller areas on the palms or soles.
- Erythrodermic psoriasis (EP): A very rare, severe form of psoriasis that can cover the entire body with a red, peeling rash that can itch or burn intensely. EP presents with widespread redness, scaling, itching, hair loss, nail changes, and systemic symptoms such as fever, chills, fatigue, and potential cardiovascular issues
- Psoriatic arthritis: a type of inflammatory arthritis that affects some people with psoriasis, causing joint pain, stiffness, and swelling. Psoriatic arthritis occurs in up to 20% of people with psoriasis.
- Nail psoriasis: a chronic inflammatory condition affecting the nails, often associated with skin or joint involvement in psoriasis patients. It can manifest with symptoms like nail discoloration, pitting, onycholysis (separation of the nail from the bed), and subungual hyperkeratosis (thickening of the skin under the nail).
- Ocular psoriasis: systemic inflammation from psoriasis and its treatments can lead to a variety of eye complications, including keratoconjunctivitis sicca, blepharitis, conjunctivitis, and uveitis. Psoriasis patients should have regular eye exams.
The Underlying Causes of Psoriasis
Psoriasis is a multifactorial condition, meaning that several factors make it more likely that a person would develop psoriasis. The development of psoriasis is complex, and involves the following underlying causes:
Genetic Factors
Psoriasis has a strong genetic link, with individuals having a family history of the condition at higher risk of developing it [DE CID ELLINGHOUS, STUART>>>>>>>>>>]. Certain genes, like HLA-Cw6, are associated with psoriasis, particularly early onset and severe cases.
HLA-Cw6-positive patients often experience stress, obesity, streptococcal infections, and guttate psoriasis, with symptoms affecting the arms, legs, and trunk. Those with this gene and psoriatic arthritis typically show skin symptoms before joint problems and have an earlier onset of the disease. Variants of genes like HLA-Cw6 influence immune responses to triggers, ultimately increasing inflammation and rapid skin cell production.
Other genes related to immune function and skin cell growth are also linked to psoriasis.
Immune System Dysfunction
In psoriasis flare-ups, dysregulation of both the innate and adaptive immune responses causes the immune system to mistakenly attack healthy skin cells, speeding up their growth and leading to thick, scaly plaques. This creates an “inflammatory loop,” resulting in persistent plaques.
Key players in this process are dendritic cells (a type of immune cell), Th17 cells (a specialized white blood cell), and keratinocytes (skin cells). Dendritic cells release substances that activate Th17 cells, which produce inflammatory cytokines, causing skin inflammation and the overproduction of keratinocytes, further fueling inflammation.
Environmental Triggers
Environmental factors play a significant role in triggering psoriasis flare-ups or worsening symptoms.
Common triggers include physical trauma to the skin (Koebner phenomenon), infections (such as streptococcal throat infections), stress, smoking, and certain medications. These triggers can activate the immune system, causing inflammation and plaque formation. Changes in the weather have also been associated with psoriasis flares.
Certain medications (like lithium, beta-blockers, and antimalarials), lifestyle factors like alcohol consumption and obesity, environmental pollutants (e.g., air pollution, cadmium exposure), psychological stress, and hormonal or metabolic changes are also associated with psoriasis. These factors can lead to increased inflammatory responses, triggering psoriasis flare-ups.
Interestingly, skin dysbiosis (an imbalance or alteration in the skin microbiota) has also been associated with psoriasis flare-ups.
The Role of Inflammation
Chronic inflammation is a hallmark of psoriasis, driven by an overactive immune response. Inflammatory cytokines such as TNF-α, IL-17, and IL-23, are released in excess, causing the rapid growth of skin cells and leading to the thickened, red, and scaly patches characteristic of the disease.
This ongoing inflammation not only affects the skin but can also manifest in other areas of the body including the joints and digestive system, contributing to the overall burden of the disease.
Common Risk Factors for Psoriasis
There are several common risk factors for psoriasis:
Family History
The connection between a family history of psoriasis and the development of psoriasis has been strongly established in studies involving families and twins [BRANDRUP, FARBER>>>>>>>>.
Family-based studies and twin studies suggest a strong genetic component to psoriasis, with a 50% risk if both parents are affected, a 16% risk with one affected parent, and 35-72% concordance in monozygotic twins, although environmental factors may also play a role.
Age and Gender
Psoriasis seems to appear most commonly at two points in the human lifespan: it typically peaks first between 15-20 years and then again between 55-60 years.
Studies show that psoriasis tends to be equally common among men and women, although some types may show a gender preference. For example, nail psoriasis may be more common in men, whereas guttate and pustular psoriasis may be more common in women.
Stress and Mood
Both emotional stress and depression can play a significant role in triggering or worsening psoriasis symptoms. Stress can worsen psoriasis by promoting inflammation, while depression often follows due to the impact on patients' quality of life and self-image.
This cyclical relationship can lead to more severe disease manifestations and increased psychological distress, highlighting the need for a holistic approach that combines dermatological care with psychological support to manage both skin symptoms and emotional well-being effectively.
Infections
Certain infections, particularly streptococcal throat infections, are known to trigger psoriasis flares, especially guttate psoriasis. However, other infections including staphylococcus, H. pylori, Candida albicans and viral infections are also associated with psoriasis flare ups.
These infections can stimulate an immune response that results in the development of psoriasis lesions.
Obesity
There is a well-documented link between obesity and psoriasis. Excess weight can increase inflammation in the body, exacerbating psoriasis symptoms. Obese individuals are also more likely to experience severe psoriasis and have a lower response to treatment.
Smoking and Alcohol Consumption
Smoking and excessive alcohol consumption are both associated with an increased risk of developing psoriasis and can worsen the severity of the disease. These habits contribute to inflammation and negatively impact the immune system, leading to more frequent and intense flare-ups.
Medications
Certain medications can trigger or worsen psoriasis. These include lithium (used to treat bipolar disorder), beta-blockers (used for heart conditions), and antimalarial drugs. These medications can all interfere with the body's immune response, leading to psoriasis flare-ups.
Gut Dysbiosis
Psoriasis, a chronic inflammatory skin disease, may be influenced by gut health. A connection between gut health and psoriasis is being explored, especially the relationship between the gut microbiome and immune function. Alterations in the gut microbiome can affect immune system regulation, potentially contributing to psoriasis pathogenesis.
Evidence suggests that a less diverse microbiota and overgrowth of certain bacteria are common in psoriasis patients, leading to systemic inflammation.
One study noted similarities in gut microbiomes between psoriatics and people who drank excessive amounts of alcohol, characterized by reduced bacterial diversity and small bowel bacterial overgrowth.
The Connection Between Psoriasis and Other Health Conditions
The same inflammatory patterns that cause psoriasis skin symptoms can also show up in different areas of the body. Some other manifestations associated with psoriasis include:
Psoriatic Arthritis
Psoriatic arthritis (PsA) is a chronic inflammatory arthritis that affects about 20% of people with psoriasis.
Both PsA and psoriasis share an immune-mediated inflammatory process influenced by genetic and environmental factors. PsA causes inflammation in the skin, joints, and other tissues, mainly targeting entheses (where tendons and ligaments attach to bone), leading to joint damage and arthritis symptoms.
Cardiovascular Disease
Psoriasis is linked to a higher risk of cardiovascular disease because of a common link to systemic inflammation. Activated T-cells and cytokines like TNF-α, IL-17, and IL-23 in psoriasis also contribute to vascular inflammation and atherosclerosis. Psoriasis is also associated with metabolic syndrome, obesity, hypertension, dyslipidemia, and type 2 diabetes.
Studies show that people with psoriasis have up to a 50% greater risk of developing cardiovascular disease, with higher risk correlating to more severe skin involvement. Therefore, health guidelines now recommend that providers actively manage and monitor cardiovascular risk factors in psoriasis patients.
Metabolic Syndrome
Psoriasis, a chronic inflammatory disorder, often coexists with metabolic syndrome (MetS), which includes obesity, hypertension, insulin resistance, and dyslipidemia. This inflammatory state increases systemic inflammation, worsening both skin symptoms and metabolic health.
Psoriasis patients frequently have higher rates of obesity, type 2 diabetes, and cardiovascular risk factors, highlighting the need to screen for and manage MetS to improve overall health outcomes.
Mental Health
Psoriasis has massive effects on mental health, with patients experiencing higher rates of depression, anxiety, and emotional distress compared to the general population. The visible nature of psoriasis lesions, coupled with chronic discomfort and social stigma, can lead to low self-esteem, social isolation, and a reduced quality of life.
Psoriasis is also a systemic inflammatory condition, and there is evidence that systemic inflammation drives the progression of many mental health conditions like depression and anxiety.
Effective management of psoriasis should focus on skin symptoms and psychological well-being.
Managing and Reducing Risk Factors
Managing risk factors for psoriasis flare-ups begins with diet and lifestyle. Maintaining a relationship with your healthcare provider is also foundational.
Lifestyle Changes
Managing stress through relaxation techniques, maintaining a healthy weight with balanced nutrition and regular exercise, and avoiding smoking and excessive alcohol consumption are all research-based foundations to reduce the risk of psoriasis flare-ups.
The Mediterranean diet is known for its anti-inflammatory properties. It includes high consumption of fruits, vegetables, legumes, cereals, fish, nuts, and extra-virgin olive oil, while limiting the intake of meat, dairy products, and alcohol. This may help reduce systemic inflammation, which is a central feature of psoriasis.
Monitoring and Managing Comorbidities
Regular check-ups are essential for individuals with psoriasis to monitor and manage related health conditions such as cardiovascular disease and diabetes. Early detection and management of these comorbidities can help improve overall health outcomes and quality of life.
Working with Healthcare Providers
Collaborating closely with dermatologists and other specialists is foundational for effectively managing psoriasis and its associated risks. Open communication and coordinated care can lead to better treatment plans, helping to control symptoms, prevent complications, and provide a better quality of life for patients living with psoriasis.
When to Seek Medical Advice
If you’ve been living with new rashes that make you feel embarrassed to wear T-shirts or shorts, or are accompanied by other symptoms, it’s important to talk with your doctor.
Recognizing the Signs
See a doctor if you have persistent red, scaly patches that are itchy, painful, or spreading. Other signs include nail changes (pitting or nail separation) and joint pain or swelling.
Early consultation helps confirm psoriasis, rule out other conditions, and start treatment.
The Importance of Early Intervention
Early diagnosis and treatment can manage symptoms, reduce flare-ups, prevent complications like psoriatic arthritis, and improve quality of life.
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Key Takeaways
- Psoriasis is a chronic inflammatory skin disease influenced by genetics, immunity, and environmental factors, with triggers like infections, stress, and more.
- Managing psoriasis to reduce flare-ups involves healthy lifestyle choices, stress reduction, and avoiding smoking and excessive alcohol.
- Regular monitoring and personalized treatment plans are essential. While psoriasis is lifelong, it can be effectively managed with informed care and lifestyle adjustments, leading to fewer flare-ups and better well-being.
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