Final answer:
A social worker should first consider a diagnosis of Substance use disorder for an adolescent exhibiting poor academic performance, frequent lies, manipulative behavior, and changed friendship patterns, but should also keep in mind conditions like Specific learning disorder and Major depressive disorder.
Step-by-step explanation:
When a social worker sees an adolescent for poor academic performance coupled with frequent lying, manipulative behavior, and a shift in friendship patterns, they should consider several possible diagnoses. Given the information provided, the first diagnosis to consider may be Substance use disorder (A). The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), outlines the criteria for substance use disorders, and these include a pattern of compulsive drug use with potential physical and psychological dependence. The adolescent's behavior could be indicative of attempting to hide substance use and the resulting interpersonal problems that often accompany this disorder.
The social worker should also consider other possibilities like Specific learning disorder (C) which is a neurological disorder that could lead to academic difficulties, and Major depressive disorder (D), which could manifest as changes in behavior and social engagement. Nevertheless, given the behaviors like manipulation and lying, which more typically align with efforts to hide drug use and maintain access to substances, Substance use disorder is a logical first consideration.