David H. Shaw

EEG sleep in outpatients with generalized anxiety: A preliminary comparison with depressed outpatients

To develop further perspective on the psychophysiology of generalized anxiety disorder and primary depression, all-night electroencephalographic (EEG) sleep measures in outpatients with diagnoses of generalized anxiety disorder and primary (nondelusional) depression were compared. Both groups had difficulty initiating and maintaining sleep, and diminished amounts of slow-wave sleep. Compared to patients with generalized anxiety disorder, depressives had a shorter rapid eye movement (REM) latency, greater REM sleep percent and eye movement activity, and a different temporal distribution of REM sleep. Anxious patients showed few changes from first to second night, whereas depressives showed increases in several REM sleep indexes. The combination of REM sleep latency and REM percent correctly classified 86.7% of patients. These data may provide a more direct measure of central nervous system arousal and sleep/wake function than previous studies in the psychophysiology of anxiety. They also lend support to the clinical distinction between generalized anxiety disorder and primary depression and to the classification of anxiety states as disorders of initiating and maintaining sleep.

Effects of Aging on EEG Sleep in Depression

Many of the same electroencephalographic sleep measures which differentiate between normals and depressed patients have also shown differences among age groups within a normal population. The present study examines sleep measures in 87 inpatients with a major depressive syndrome, examining the specific sleep variables which are correlated with age between 18 and 60 years. REM latency shows a distinct decline with age, an effect not well demonstrated in normals. Thus, REM latency may differ from variables which measure aspects of awakening and which show a clear age trend in normal subjects. Since many sleep measures are greatly skewed or have truncated distributions, the present paper provides several alternative styles of measurement which allow comparisons to be made easily and also facilitate multivariate testing.

EEG sleep, depression, and aging

To date little attention has been paid to the possible age-dependent relationships of EEG sleep measures in depression or to the implications of such relationships for diagnostic sensitivity and specificity. In a study of 108 patients with major depressive disorders (67 inpatients, 41 outpatients), age was shown to be a very powerful determinant of electroencephalographic (EEG) sleep patterns. Thus, among other sleep variables, sleep efficiency, delta sleep percent, and REM latency all showed significant linear declines with increasing age. Similar trends were seen in both inpatients and outpatients. Some variables were without age trends (age-stable), including sleep latency, REM sleep percent, and REM activity. These findings confirm those of an earlier report from our laboratory [45] and suggest that age-corrected sleep variables can be developed for clinical diagnostic application. Thus, using normative data from Gillin et al. [19] for comparison, a sensitivity level of 65% for age-corrected REM latency was demonstrated, together with a specificity of 95% and a diagnostic confidence of 92%. Data from a pilot study comparing EEG sleep measures in depression and dementia are also presented; these data suggest the potential utility of EEG sleep measures in the differential diagnosis of these two disorders, especially in patients with mixed symptoms. Additional areas for further research are reviewed with enumeration of specific testable hypotheses.

RBC and plasma choline levels in control and depressed individuals: A critical evaluation ☆

Red blood cell (RBC) and plasma choline (Ch) were measured in 78 depressed, drug-free patients and in 23 normal, drug-free control subjects. RBC Ch levels displayed a huge variability among the patients, in contrast to those measured in normal controls. Plasma Ch levels, on the other hand, were more consistent within each group, and were correlated with age among the two populations studied. RBC Ch levels would appear to be independent of plasma Ch levels, and to be highly individualized and reproducible within each subject. A segment of the depressed population exhibited significantly higher RBC Ch levels than those seen in the normal control population. A clinical correlation of RBC and plasma Ch levels within the depressed population indicated that the patients with RBC Ch levels exceeding 35 nmole/ml might represent a diagnostically distinct subpopulation with specific clinical characteristics. Results presented here, although preliminary, suggest a role for RBC Ch as a biological marker in certain categories of depressive illness.

REM sleep, naps, and depression

Continued interest in rapid eye movement (REM) sleep abnormalities in depression stimulated comparative studies on daytime naps versus nighttime sleep. In a group of 15 depressed patients, REM latencies in morning and afternoon naps were similar to the shortened REM onset at night. Although REM latency did not vary across the three times, the propensity for REM sleep appeared to be greater in the morning nap than in the afternoon nap and the early portion of nocturnal sleep. Finally, the data suggest that responders to tricyclic treatment tend to be poor sleepers during daytime naps.

Electroencephalographic sleep findings in depressed outpatients

We compared the electroencephalographic (EEG) sleep characteristics of 20 outpatients with those of 20 age-matched inpatients with major primary depressive disorders. Both groups showed similar patterns of sleep disturbance: reduced rapid eye movement (REM) sleep latencies, sleep efficiencies, and slow wave sleep. While the inpatients had greater REM activity in the first REM period than did the outpatients, both groups showed evidence of greater REM sleep time and REM activity during the first half of the night than do normals. The outpatients demonstrated a level of adaptation in that more REM sleep time and activity were present on night 2 than on night 1.

Electroencephalographic Sleep Recordings and Depression in the Elderly

Eighteen patients over the age of 60 who were experiencing a major depressive episode were studied on a Clinical Research Unit after they had been drug‐free for at least two weeks. All‐night electroencephalographic (EEG) recordings revealed considerable fragmentation of sleep, a mean sleep efficiency of 58 percent, and very little delta sleep. The findings of reduced sleep time, shortened REM latency, and high REM density were similar to those in depressed patients under the age of 60. These preliminary findings support the application of EEG sleep recordings as a tool for the differential diagnosis of depression in the elderly.

EEG SLEEP AND AFFECTIVE DISORDERS: WHAT CAN IT PREDICT?

Our current studies on patients with primary depression have established that early EEG sleep changes on amitriptyline are highly correlated with the final clinical response four weeks after initial drug administration. These immediate changes which include rapid REM suppression (43%) and prolongation of REM latency (187%) suggest an initial alteration in multitransmitter levels which may relate to eventual clinical change. Since catecholaminergic and cholinergic neurons have been implicated in the control and intensity of REM sleep, a more active search for REM sleep-tricyclic drug mechanisms is warranted.