Altered Sensory Phenomena Experienced in Bipolar Disorder

In an earlier report (1), the first author described a variety of altered nonpsychotic sensory changes reported to him or acknowledged on questioning by patients with bipolar II disorder. While such a phenomenon has been long described—with Clifford Beers observing in his 1908 classic, A Mind That Found Itself (2), “The tricks played upon me by my senses of taste, touch, smell, and sight were the source of great mental anguish” (p. 29)—it has been minimally detailed or studied. DSM-5 observes that during manic episodes some patients may perceive a “sharper sense of smell, hearing, or vision,” and ICD-10 lists hyperacusis as a possible concomitant of mania.

The few reports or studies of such phenomena have been limited to relatively narrow domains or research questions. For example, Lahera et al. (3) reported that euthymic bipolar patients showed impaired olfactory function; Cumming et al. (4) described olfactory identification as compromised in patients with a bipolar disorder; and Hardy et al. (5) reported that in manic states, some patients had a decreased sensitivity to odor detection. Swiecicki et al. (6) reported that patients with bipolar depression rated fewer gustatory stimuli as unpleasant and more olfactory stimuli as pleasant compared with unipolar depressed patients. O’Bryan et al. (7) reported a deficit in visual motion perception in bipolar patients (both when euthymic and when ill), and Kéri et al. (8) reported that bipolar patients had impaired visual processing during depressed phases, which normalized when euthymic.

As so little has been written on such sensory changes, we undertook a study examining multiple sensory domains, while also seeking to establish whether nonpsychotic sensory changes were limited to patients with bipolar II disorder or were also experienced by those with bipolar I disorder.

Participants were recruited via the Black Dog Institute Clinic. Patients who met DSM-IV criteria for a bipolar disorder were invited to take part in a study assessing perceptual changes experienced by those with a bipolar disorder. While 257 patients indicated their provisional willingness to take part, only 66 proceeded to the telephone interview—18 with bipolar I disorder, 36 with bipolar II disorder, and 12 with “soft” bipolar disorder (i.e., patients who did not meet the DSM duration criteria). The participants’ mean age was 35.9 years, and slightly more than half of the sample were women (55%).

The interviewer asked whether participants had experienced any of 10 differing “perceptions” during hypomanic/manic and/or depressive states, and if they did, the interviewer asked for details. Responses were coded as “heightened,” “muted,” or differing in some other way. Responses indicative of psychotic symptoms were excluded (only 29% had experienced delusions, and 24% hallucinations).

Among the primary senses (smell, taste, vision, touch, hearing), 82% experienced changes during a hypomanic/manic episode, and 65% during a depressive episode. Analyses failed to identify any significant differences in the number of sensory changes reported for participants with bipolar I, bipolar II, and soft bipolar disorder during depressive episodes, but a significantly greater number of sensory changes were reported during hypomanic/manic episodes for the bipolar I participants compared with the soft bipolar participants.

In relation to smell, during hypomanic/manic states, only one participant reported a weakening in smell, while 19 reported a heightening, using terms like “sharper,” “clearer,” “stronger,” and “more intense.” Some reported smelling things that other people could not smell. Of the 16 participants reporting such changes when depressed, 12 reported smells as weaker (e.g., dull, degraded, less strong) and two as stronger, and several described smells as annoying or sickening.

Of the 22 participants who acknowledged taste changes during a hypomanic/manic episode, most described tastes as stronger or heightened, and one described them as weaker or different (e.g., “metallic” or bland “like cardboard”). Thirty-three reported taste changes when depressed; most described having a weaker sense of taste, or food tasting bland, and three reported qualitative changes (two experiencing food as “bad” and one as “metallic”).

Of the 21 who acknowledged visual changes during a hypomanic/manic episode, 14 described them as an improvement (i.e., sight sharpened, colors brighter and more vibrant) and one a worsening (noting that things looked foggy and unclear), and several reported nonspecific changes. Thirteen experienced visual changes during depressive episodes—nine as worse (i.e., objects dull, gray, or gloomy, difficulties in seeing things or in focusing their vision) and one as improved, and three reported nonspecific changes.

Changes in sense of touch were acknowledged by 29 participants during hypomanic/manic episodes, with 24 reporting touch as more sensitive or hypersensitive, one as less sensitive, and three as “different.” Greater sensitivity was not always pleasant; three participants described feeling itchy or not being able to wear “itchy” clothes. Four participants highlighted feelings of sensuality and heightened pleasure from being touched. Of the 15 who affirmed changes during depressive episodes, five felt more sensitive, seven felt less sensitive, and three reported other experiences.

Nineteen participants affirmed changes in hearing during a hypomanic/manic episode, with 13 reporting improvement and six describing “different” hearing. Improved hearing generally involved amplification, sounds heard more clearly, or subthreshold sounds being heard distinctly. Eight affirmed changes during depressive episodes, with half reporting their hearing as worse and two as improved, and two describing nonspecific changes. Participants reported being more aware of certain sounds (e.g., yelling, chewing) and high-pitched sounds, or finding sounds “annoyingly loud.”

We also inquired into five other sensory phenomena, with 53 participants reporting changes in danger perception, 39 changes in intuition, 55 changes in empathy or connectedness, and 29 changes in their ability to predict future events; five experienced synesthesia, which was reported during both hypomanic and depressive episodes. Table 1 provides exemplar descriptions of such phenomena experienced during hypomanic and depressive episodes.

Among the study limitations were that only a minority of invitees proceeded to interview and that our sample was unlikely to be representative of all patients with a bipolar condition, as our recruitment strategy would have resulted in overrepresentation of those who experienced altered sensory episodes and who were perhaps keen to learn more about the meaning of such phenomena. Also, while we examined changes in accepted sensory domains (smell, taste, vision, touch, and hearing, as well as synesthesia), the extent to which changed perceptions of connectedness, empathy, danger, and intuition are sensory changes or are more related to intrinsic hypomanic/manic mood states is somewhat problematic.

In our earlier report (1), it was implied that altered sensory phenomena may be confined largely to patients with a bipolar II disorder and relatively rare in bipolar I disorder. Despite limitations in sample representativeness and the comparatively small number of participants with bipolar I disorder, a key finding of the present study is that such phenomena may be equally common in bipolar I and II disorders, and perhaps even more common in bipolar I disorder. Our earlier report limited consideration of sensory changes to hypomanic/manic states. By asking our participants about such constructs during their depressive episodes, we also established the presence of depression-related sensory changes but with most changes being the converse of those experienced during hypomanic/manic states and generally evidencing a dampening or tamping phenomenon (a bipolar dimension)—although some participants reported a greater sensitivity to some stimuli during depressed states.

We sought to identify only nonpsychotic sensory experiences and changes, but the degree to which we can be confident that psychotic phenomena as well as overvalued ideas were excluded is unclear. The table details some descriptors that might be viewed as psychotic (e.g., feeling “like people are watching,” seeing “vertical white lines,” and perceiving auras or glows around people). In the first author’s judgment, it is not uncommon, however, for those with nonpsychotic bipolar states to report seeing things out of the corner of their eye or seeing lines, while simply “feeling” being watched is not necessarily “psychotic.”

One limitation to our methodological approach is that we failed to establish the mood state of the study subjects at the time of their interview, and it may be that such recollections were influenced by the individual being hypomanic, depressed, or euthymic.

These observations allow several conclusions and raise several questions. It would appear that sensory changes during mood swings in individuals with a bipolar disorder are unlikely to be rare, and it is therefore of interest that they have not been detailed in phenomenological descriptions of the bipolar disorders. As patients rarely volunteer comments on such perceptions, is it that they are concerned that reporting them might be judged as evidencing psychosis (and does that indeed occur?), or do they simply view them as correlates of their mood state? If such sensory changes are limited to the bipolar disorders, the phenomenon has the potential to advance detection and formal diagnosis of these disorders. Furthermore, functional MRI studies and examination of physiological responses to laboratory stimuli during manic and depressive phases would be worth undertaking in patients reporting such phenomena. Finally, do such phenomena have ecological advantages, perhaps contributing to the recognized overrepresentation of creativity among individuals with a bipolar disorder?