Altered mental status and allied cognitive disorders in HIV-infected patients have devastating consequences for patients and carers. Neuropsychological deficits also have a negative impact on the quality of life.  These may arise as a direct effect of HIV infection: for example, as part of a spectrum of HIV-associated neurocognitive disorders (HAND) or as a psychiatric comorbidity (e.g., depression or alcohol/substance abuse). While HIV-related opportunistic infections and neoplasms may also present with progressive cognitive decline and personality changes, more often they manifest as an acute neurological emergency. Patients are also at risk of ischaemic stroke, and this should be considered in the setting of acute neurological deterioration.
Early detection and treatment of HAND improves prognosis; poor performance in neuropsychological tests is associated with increased mortality.  Diagnosis and prompt treatment of CNS opportunistic infections or tumours are of obvious importance in reducing morbidity and mortality, although patients with CNS opportunistic infections may have a high prevalence of residual cognitive impairment. 
Combination antiretroviral therapy (CART) has reduced the prevalence of the most severe form of HIV cognitive impairment, prolonged survival,   and has improved the quality of life of HIV patients presenting with cognitive problems;  and it may improve psychiatric comorbidity, such as depression.  CART has also reduced the age-associated risk for HIV-associated dementia (HAD)   and decreased the incidence of CNS opportunistic infections. However, the use of CART itself may occasionally result in altered mental status, either directly as a medication adverse event, or as a consequence of therapy-related immune reconstitution inflammatory syndrome (IRIS).
Psychiatric comorbidity is highly prevalent in HIV-infected individuals. Depression is associated with low compliance with antiretroviral treatments  and, potentially, with a more rapid disease progression.  Patients who are depressed, have anxiety, or have a substance abuse disorder at the time of initiating CART have a poorer virological response to treatment.  Antidepressant therapy improves quality of life and treatment adherence,  and decreases cognitive complaints. 
A number of resources are available that provide information on the assessment of neurological upset in HIV-infection, as well as general and specific guidance on the diagnosis and treatment of opportunistic infections. 
- Asymptomatic neurocognitive impairment (ANI)
- Mild neurocognitive disorder (MND)
- Antiretroviral adverse effects
- Toxoplasmosis encephalitis/abscess
- Cryptococcal meningitis/abscess
- Mycobacterium tuberculosis meningitis/abscess
- Substance abuse
- Alcohol abuse
- Hepatitis C co-infection
- Hepatitis B co-infection
- Adrenal insuffiency