neural explanations

• Low levels of serotonin lowers mood 


  Neurotransmitters are responsible for relaying information from one neuron to another.

  E.g if a person has low levels of serotonin then normal transmission of mood-relevant information does not take place and mood (and sometimes other mental processes) is affected. 
• Decision making symptoms in frontal lobes impaired 


  Some cases of OCD and in particular hoarding disorder, seem to be associated with impaired decision making. 

  This in turn may be associated with abnormal functioning of the lateral (side bits) frontal lobes of the brain.

  The frontal lobes are responsible for logical thinking and making decisions. 
• Parahippocampal gyrus dysfunctional 


  There is also evidence to suggest that an area called the left Parahippocampal gyrus, associated with processing unpleasant emotions, functions abnormally in OCD.