OVERVIEW OF POLYCYSTIC KIDNEY DISEASE
Polycystic kidney disease (PKD) is an inherited disorder that causes clusters of cysts to grow in the kidneys. The cysts are filled with fluid and can enlarge the kidneys, replacing much of their normal structure. The abnormal shape leads to chronic kidney disease, which can then over time lead to reduced kidney function and even kidney failure. While most cysts develop in the kidneys, PKD cysts can also develop in the liver and elsewhere throughout the body.
Polycystic kidney disease is caused by genetic defects that are inherited. In rare cases, a mutated gene can be the cause of the disease. There are two types of polycystic kidney disease, each of which is caused by different genetic flaws. The most common type is autosomal dominant polycystic kidney disease (ADPKD), which typically develops between the ages of 30 and 40 and requires only one parent to have the abnormal gene. Autosomal recessive polycystic kidney disease (ARPKD) is a less common type of PKD that typically develops shortly after birth or during childhood. Both parents must have abnormal genes for this type of disease.
PKD commonly causes high blood pressure. Other symptoms caused by the disease include back or side pain, headaches, blood in urine, an increase in abdomen size, frequent urination, kidney stones, urinary tract or kidney infections and kidney failure. Brain aneurysms, heart valve abnormalities, colon problems and chronic pain can also develop from the disease.
There is no cure for polycystic kidney disease, but lifestyle changes and medical treatments can help reduce kidney damage and manage blood pressure. By controlling high blood pressure, the progression of the disease and subsequent kidney damage can be delayed. Medication is often used to manage chronic pain. Additional treatments are necessary if bladder or kidney infections, blood in the urine, kidney failure or aneurysms, develop.
FINDINGS: EFFECTS OF CANNABIS ON POLYCYSTIC KIDNEY DISEASE
While clinical studies on cannabis’ effect on polycystic kidney disease are lacking, findings in preclinical studies suggest cannabinoids found in cannabis could offer therapeutic benefits for treating kidney disease. One animal study found that a major cannabinoid found in cannabis, cannabidiol (CBD) effectively reduced oxidative stress, inflammation and cell death in the kidney and improved renal function, causing the researchers to conclude CBD may be effective at preventing kidney disease (Pan, et al., 2009). These protective effects of CBD are likely due to its activation of the endocannabinoid system’s CB2 receptors, which another study found was effective at protecting the kidney from damage by minimizing inflammation and oxidative stress (Mukhopadhyay, et al., 2010).
Cannabis may also limit kidney damage caused by polycystic kidney disease by potentially lowering blood pressure. Both animal and human studies have found that cannabinoids cause blood vessels to vasodilate, which in turn improves blood flow and reduces blood pressure (Stanley & O’Sullivan, 2014a) (Stanley & O’Sullivan, 2014b) (Herradon, Martin & Lopez-Miranda, 2007) (Batkai, et al., 2004). CBD specifically has shown provide vasodilation, which researchers found allowed for greater blood flow and reduced damage (Stanley, Hind & O’Sullivan, 2013).
In addition, cannabis can help polycystic kidney disease patients manage their chronic pain levels. Cannabis has been shown to significantly lower both neuropathic and nociceptive pain; even managing chronic pain that had previously proven refractory to other treatments (Boychuck, Goddard, Mauro & Orellana, 2015) (Wallace, et al., 2015) (Lynch & Campbell, 2011). Because of cannabis’ effectiveness, surveys have found that use is prevalent among those experiencing chronic pain (Ware, et al., 2003). In one study, 12 of 15 chronic pain patients who smoke herbal cannabis reported an improvement in pain (Ware, Gamsa, Persson & Fitzcharles, 2002). Cannabis has also been shown to offer a therapeutic role for headaches, which are common in those with polycystic kidney disease (Baron, 2015).