A method for diagnosing a neurological disease comprising detecting a neurological disease-specific biochemical marker macromolecule within a sample of extracted cerebral spinal fluid is disclosed. In particular, a radioactively labeled photoaffinity probe is used to diagnose a neurological disease. For instance, Alzheimer\u27s disease can be diagnosed by detecting a disease-specific protein having a molecular weight of about 42,000 daltons, i.e., glutamine synthetase
