Cognitive impairment in late-life depression (LLD) is highly prevalent,
disabling, poorly understood, and likely related to long-term outcome.
To determine the characteristics and determinants of neuropsychological
Cross-sectional study of groups of LLD patients and control subjects.
Outpatient, university-based depression research clinic.
One hundred patients without dementia 60 years and older who met DSM-IV criteria for current episode of unipolar major depression
(nonpsychotic) and 40 nondepressed, age- and education-equated control subjects.
Main Outcome Measures
A comprehensive neuropsychological battery.
Relative to control subjects, LLD patients performed poorer in all cognitive
domains. More than half exhibited significant impairment (performance below
the 10th percentile of the control group). Information processing speed and
visuospatial and executive abilities were the most broadly and frequently
impaired. The neuropsychological impairments were mediated almost entirely
by slowed information processing (β = .45-.80). Education (β = .32)
and ventricular atrophy (β = .28) made additional modest contributions
to variance in measures of language ability. Medical and vascular disease
burden, apolipoprotein E genotype, and serum anticholinergicity did not contribute
to variance in any cognitive domain.
Late-life depression is characterized by slowed information processing,
which affects all realms of cognition. This supports the concept that frontostriatal
dysfunction plays a key role in LLD. The putative role of some risk factors
was validated (eg, advanced age, low education, depression severity), whereas
others were not (eg, medical burden, age at onset of first depressive episode).
Further studies of neuropsychological functioning in remitted LLD patients
are needed to parse episode-related and persistent factors and to relate them
to underlying neural dysfunction.