Why do many patients with neurodevelopmental disorders develop secondary disorders?

a. Their genes predispose them to schizophrenia.

b. Stimulant medications cause new behavioural disorders.

c. Behavioural therapies only improve neurodevelopmental disorders.

d. Dysfunction in the brain can affect many aspects of the body.

The loss of nervous system functionality associated with neurodegenerative conditions is typically brought on by neuronal death. As more and more neurons die, these disorders typically get worse with time. Where in the nervous system neurons die determines a particular neurodegenerative disease's symptoms. For instance, the cerebellum experiences neuronal loss as a result of spinocerebellar ataxia.

Numerous aspects of the body can be impacted by brain dysfunction. When the development of the neurological system is disrupted, neurodevelopmental problems emerge. Neurodevelopmental diseases fall into a number of distinct categories. Some, like Down syndrome, result in intellectual deficiencies. Others specifically impact the motor system, learning, or communication. Complex symptoms can be present in some diseases, such as autism spectrum disorder and attention-deficit/hyperactivity disorder.

The rest of the options are irrelevant to the question.