The terms psychodiagnostic assessment and personality assessment are often used interchangeably. However, while these terms can be used to describe the same process, they can also describe different processes as well, which can be confusing!
At its most simplistic, psychodiagnostic assessment refers to the process of identifying and diagnosing mental illness. A psychodiagnostic assessment may rely on semi-structured or structured interviews, the completion of standardized measures, and, if consent is given, contact with other sources like family members, partners, and other health professionals. Each clinician may use a different method or different measures, however, the goal of a psychodiagnostic assessment is to provide the client with information about whether or not they meet diagnostic criteria for a mental illness.
The term personality assessment is sometimes used to mean a psychodiagnostic assessment. However, while they can look the same, they are not necessarily the same thing. Personality assessment refers to the use of specific measures that help identify personality traits and styles. Some personality assessment measures also include questions that assess mental illnesses. However, personality measures alone are not adequate to provide a diagnosis of a mental illness. Personality assessment measures are often (but not always) included in a psychodiagnostic assessment. Some common personality assessment measures include the Personality Assessment Inventory (PAI), Millon Clinical Multiaxial Inventory – 4th edition (MCMI-IV), and the Minnesota Multiphasic Personality Inventory – 2nd edition (MMPI-2).
An assessment or a diagnosis are not required to start treatment! However, the assessment process can be helpful if you are unclear regarding what might be going on for you, or if you believe that formally obtaining a diagnosis might be beneficial for you in some way. For instance, some treatment programs require a diagnosis in order to be eligible to participate.