Reversible Intellectual Impairment: An Internist's Perspective

Abstract

A review of the relevant literature was stimulated by recent publications urging extensive laboratory assessment of elderly patients presenting with intellectual impairment. Published data regarding reversible causes of impairment are limited and exist only for hospitalized patients, with rare exceptions. The frequencies of azotemia, hyponatremia, volume depletion, hypoglycemia, cardiac arrhythmia, cerebrovascular disease, sensory impairment, hypercarbia, congestive heart failure, infections, subdural hematoma, and chemical intoxications as causes of the intellectual impairment are entirely unknown. It is reported that 8 per cent of patients hospitalized for dementia are depressed; alcoholism is causative in 8 to 13 per cent of patients with mental impairment; normal pressure hydrocephalus is reported in 7 to 12 per cent. The frequency of the latter conditions in outpatients is not known. While estimates exist for the frequencies of hypothyroidism, hyperparathyroidism, neurosyphilis, and vitamin B12 and folate deficiencies among the elderly, no prevalence data exist for these disorders among the intellectually impaired.

Reversible Long‐standing Dementia with Normocalcemic Hyperparathyroidism

“…Hypercalcemia is a well‐known cause of reversible confusion 3 . In this case of long‐standing dementia, serum calcium values were repeatedly in the normal range.…”

Neurocognitive Aspects of Hypothyroidism

“…Unfortunately, one cannot always be sure that these neuropsychological findings are exclusively due to the effects of hypothyroidism, because the likelihood of comorbidity with neurodegenerative disorders or other factors influencing cognitive status 57 may be quite high. It has often been argued that more emphasis should be placed on the appropriate social management of patients with cognitive decline related to hypothyroidism, 72 and that classification of reversible and irreversible forms of dementia 65 be avoided. Clearly, more data are needed to determine the extent to which hypothyroid dementia can be treated and the level of disease severity for which pharmacological intervention would be most effective.…”

Cortisol Deficient State

“…In persons with cognitive impairment, a treatable condition is present 10–20% of the time 2 – 4 . The laboratory evaluations with the exception of plasma Cortisol levels of patients with treatable dementia have been described previously 5 – 7 …”