Human body and current flow effects
The effects of electric shock are many, and most of them seem to do with neuropathy, that is, damage to the nervous system, including the brain. From the Wiki article on electric shock:


  Many people survive electrical trauma only to find a host of injuries
  including loss of consciousness, seizures, aphasia, visual
  disturbances, headaches, tinnitus, paresis, and memory disturbances.
  Even without visible burns, electric shock survivors may be faced with
  long-term muscular pain and discomfort, fatigue, headache, problems
  with peripheral nerve conduction and sensation, inadequate balance and
  coordination, among other symptoms. Electrical injury can lead to
  problems with neurocognitive function, affecting speed of mental
  processing, attention, concentration, and memory. The high frequency
  of psychological problems is well established and may be
  multifactorial. As with any traumatic and life-threatening experience,
  electrical injury may result in post traumatic psychiatric disorders.


The mechanisms are unclear. Why, for instance, does ECT (Electroconvulsive Therapy) seem to work?

Electrolysis does not seem to be a factor.