What causes erectile dysfunction?

So what actually causes erectile dysfunction? When reviewing through the phases of reproduction you can see that the first two phases are directly related to erectile dysfunction. This diagram is a short mind map that will facilitate your understanding but it is very complex and every aspect needs to be considered.

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Commonly erectile dysfunction is usually caused by:

1. Poor blood flow
   When blood flow is bad this causes the penis to be unable to erect and we need to work-up a few etiologies like::

   • Diabetes causes narrowing of blood vessels and reduces the caliber of the vessels to transport blood
      

   • The reduction of nitric oxide may be multifactorial and is a diagnosis of exclusion. Once you have excluded all the other causes then you can shift your diagnosis to Nitric Oxide reduction.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
      

   • Cholesterol also forms vessel cholesterol plugs (atherosclerosis) which narrows the vessels and reduces the blood flow to the penis.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
      

2. Psychological

   • This is another complicated condition that is difficult to treat as the problem of being unable to get a good erection is due to problems of the mind. Take for example: if my patient is stressed and constantly thinking about his work; then he will not be getting an erection with all the stress.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
      

   • Low self-esteem. I had many patients who are indirectly affected by presumed erectile dysfunction. Many of my cases their partner commented something about their sexual performance, which cause the man to suffer insecurity about his manhood.
     Read more about the experience of low-self esteem causing erectile dysfunction: coming soon!
      

3. Drugs

   • There are many drugs that can cause erectile dysfunction and some of them are so common that many people have forgotten that those medications can reduce blood flow to the penis, therefore indirectly affecting the hardness of the erection.
      

   • Common drugs causing erectile dysfunction:

     • Beta-blockers (nifedipine, atenolol, metoprolol, carvedilol, bisoprolol) usually can be associated with erectile dysfunction.

     • Calcium channel blockers
        

   • Illicit drugs causing erectile dysfunction:

     • Erection is caused by parasympathetic activation and penile flaccidity is caused by sympathetic activation. Drugs like Methamphetamine, Ketamine, and Ecstasy keep the body in a sympathetic state, which causes the blood flow to the penis to diminish therefore causing flaccidity of the penis.
       
        

4. Nerve damage
   Nerves are like wires which bring impulses to the penis and thus evoke a response but, damaged nerves are different as they are unable to bring the impulses to hit a threshold as a response to get an erection. There are many causes of nerve damage such as diabetes, lumbar radiculopathy, pudendal neuralgia, or pudendal neuropathy. These are a few examples of nerve damage causing erectile dysfunction.

    

   • Diabetes is known to cause generalized nerve injury when glucose levels in cells are high. This glucose may bond with cell proteins and alter their structure and these glycosylated proteins have been implicated in diabetic neuropathy. A very similar occurrence was studied in animals where high glucose indirectly increases Protein Kinase C. High blood glucose levels increase the amount of intracellular diacylglycerol which activates protein kinase C. This protein kinase C reduces the speed of conduction in nerves and in turn reduces stimulation and blood flow.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
      

   • Lumbar radiculopathy can also cause erectile dysfunction. There are new studies that look into lumbosacral radiculopathy which causes sexual dysfunction. This new study shows that L5-S1 disc herniation can cause erectile dysfunction and was not widely reported. With this new data is it safe to say that most men with disc herniation suffer from erectile dysfunction but the sexual dysfunction is masked by other more debilitating symptoms such as back pain, leg numbness and incontinence, therefore, the subjects did not highlight their erectile dysfunction as the main problem associated with disc herniation.
      

   • Pudendal neuralgia causes pain and this misfiring will reduce blood flow to the penis.
     
      

5. Hormonal

   • Hormones are important in helping with erection. It is a very complex process to explain how testosterone can improve erection
      

6. Structural anomaly

   • Peyronie's disease is the development of fibrous scar tissue inside the penis that causes curved, painful erections. Penises vary in shape and size, and having a curved erection isn't necessarily a cause for concern. But Peyronie's disease causes a significant bend or pain in some men. This can prevent you from having sex or might make it difficult to get or maintain an erection (erectile dysfunction).​
     
     
     
     
     
     
     
     
     
     
     
     
     
     
      

7. Smoking

   • Smoking has always been associated with constriction of blood vessels and if frequently seen in Raynaud's disease (cold hands and feet). Raynaud's disease is an obvious example of the detrimental effects of smoking. Smoking causes the blood vessels to constrict and reduce blood flow to the extremities causing Raynaud's Disease and likewise to the penis. When blood flow is reduced to the penis, it can often become difficult to get an erection.
      

8. Spinal cord diseases and spinal cord trauma

   • Spinal cord or spinal nerves-related problems will in turn affect the nerve supplying the penis which is important in the Stimulation and Erection phase. If there is any damage to the spinal cord or spinal nerves, then the impulses to stimulate the penis to reach the erection phase will be reduced. Basically, the damaged spinal cord and nerves are like short-circuit electrical wires which do not carry electricity well, therefore, causing dysfunction of the penis. 
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
      

9. Brain trauma 

   • The brain is a complex structure with many functions. It is a center of converting intent into action (take for example: having the intention of lift your hand by changing electrical impulses of intent into action to lift the arm) and center of thought.

   • We have higher and primordial (primitive) brain function. The basic instinct to propagate is through sexual desires (a form of primordial brain function) and the process to translate the instinct into sexual activity is considered as higher brain function.

   • People with brain injury can either lose one or both brain functions (primordial or higher brain function). This can depress sexual stimulation and or sexual function, which, leads to erectile dysfunction.