Under Cayley–Dickson constructions, the sedenions 
  
    
      
        
          S
        
      
    
    {\displaystyle \mathbb {S} }
   constitute a further fourth extension over 
  
    
      
        
          R
        
      
    
    {\displaystyle \mathbb {R} }
  . The real numbers are ordered, commutative and associative algebras, as well as alternative algebras with power-associativity.
It is also present in many patients with Parkinsons disease or Lewy body dementia resulting from sympathetic denervation of the heart or as a side effect of dopaminomimetic therapy. This rarely leads to fainting unless the person has developed true autonomic failure or has an unrelated heart problem.Another disease, dopamine beta hydroxylase deficiency, also thought to be underdiagnosed, causes loss of sympathetic noradrenergic function and is characterized by low or extremely low levels of norepinephrine, but an excess of dopamine.Quadriplegics and paraplegics also might experience these symptoms due to multiple systems inability to maintain normal blood pressure and blood flow to the upper part of the body. Causes
Some causes of orthostatic hypotension include neurodegenerative disorders, low blood volume (e.g. caused by dehydration, bleeding, or the use of diuretics), drugs that cause vasodilation, other types of drugs (notably, narcotics and marijuana), discontinuation of vasoconstrictors, prolonged bed rest (immobility), significant recent weight loss,  anemia, vitamin B12 deficiency, or recent bariatric surgery. Medication
Orthostatic hypotension can be a side effect of certain antidepressants, such as tricyclics or monoamine oxidase inhibitors (MAOIs). Marijuana and tetrahydrocannabinol can on occasion produce marked orthostatic hypotension. Alcohol can potentiate orthostatic hypotension to the point of syncope. Orthostatic hypotension can also be a side effect of alpha-1 blockers (alpha1 adrenergic blocking agents). Alpha1 blockers inhibit vasoconstriction normally initiated by the baroreceptor reflex upon postural change and the subsequent drop in pressure. Other factors
Patients prone to orthostatic hypotension are the elderly, post partum mothers, and those having been on bed rest.