ABSTRACT
Obsessive compulsive disorder (OCD) has clear af®nities with Tourette's syndrome, though it is less of a movement disorder, and more of a cognitive or psychiatric condition. In this chapter we shall see how its particular pattern of loss of self-regulation and control, and problems with the natural inhibition of thought and action, can be devastating for the sufferer, who knows how irrational are his/her obsessive thoughts and consequent compulsive actions. We shall see that OCD lies within a spectrum of related conditions and, further, is comorbid with a range of other neuropsychiatric, developmental, and frontostriatal disorders. We shall in this context note that many of the obsessions and compulsions are natural extensions of the preoccupations of normal childhood, and indeed in nonclinical form are clearly adaptive or protective. We shall discuss the genetics of the condition, and how genetic factors may interact with environmentally predisposing agents in the form of vulnerability genes. We shall note the neuropsychological consequences of the disorder, and the associated neuropathology, which affects aspects of the frontostriatal system and related circuitry. After discussing the neurochemistry of the disorder, which involves a range of modulatory neurotransmitters and neuropeptides, many of which are known from animal studies to play a role in obsessive compulsive behaviours in humans, we shall brie¯y address the treatment options.
