Clinical Constructs and Digital Phenotyping

# Clinical Constructs and Digital Phenotyping - [[Digital Phenotyping]] - [[Digital Interventions]] - Below is a categorized list of core constructs—latent physiological, behavioral, cognitive, and environmental processes—that researchers map onto digital proxies when studying serious mental illnesses (SMI). Each of these constructs captures a facet of daily functioning or physiology that’s often disrupted in schizophrenia, bipolar disorder, and severe depression. **Approach**: I am starting from clinical constructs to explain their relevance, and then finding associations to digital phenotyping studies. Next, I want to determine appropriate thresholds—what constitutes "high" or "low" values for these measures. **The Big So what question after this exercise?** 1. Sleep, Mobility, Phone usage, HRV seems to be used most, repeatably across clinical constructs. 2. Most papers flag “relative drop or spike” as a meaningful early warning signals rather than a raw/fixed numbers. 3. Better to combine streams of signals; e.g Short Sleep hours + Late night screen time + increased burst of text messages / tapping predict ?mania? 4. DP are proxy, direct or indirect to clinical constructs. **Note:** This construct list was adapted from clinical symptom domains commonly observed in serious mental illness (SMI) and studied. It builds on domains identified in frameworks like the DSM-5, PANSS, PHQ-9. Some come from pathophysiological research. This list is not exhaustive, but reflects core constructs that are both clinically meaningful. | **Constructs (What) “S **_**MI show up in ….**_**”** | **Relevance (Why)** | **Domain** | **DP associated with Disorders** | **Threshold (What to look out for)** | (So What?) | **DP Design (How)** | | -------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- | 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| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ | | **…Sleep & Circadian Disturbances** | e.g. insomnia, hypersomnia, irregular sleep-wake cycle (common across depression, bipolar mania, schizophrenia) Core clinical symptom (assessed in all SMI) and research focus (e.g. actigraphy studies) | Physiological | - [Mania -](https://pmc.ncbi.nlm.nih.gov/articles/PMC9167949/#:~:text=levels%20play%20a%20prominent%20role,suggesting%20that%20they%20constitute) **[Reduced](https://pmc.ncbi.nlm.nih.gov/articles/PMC9167949/#:~:text=levels%20play%20a%20prominent%20role,suggesting%20that%20they%20constitute)** [total sleep time](https://pmc.ncbi.nlm.nih.gov/articles/PMC9167949/#:~:text=levels%20play%20a%20prominent%20role,suggesting%20that%20they%20constitute) - [PTSD - fragmented sleep](https://www.nature.com/articles/s41746-025-01825-6?error=cookies_not_supported&code=6711ce5e-d4f4-48b2-ae5c-177a1675d330#:~:text=match%20at%20L272%20Concerning%20sleep,was%20the%20only%20feature%20associated) **[Fragmented](https://www.nature.com/articles/s41746-025-01825-6?error=cookies_not_supported&code=6711ce5e-d4f4-48b2-ae5c-177a1675d330#:~:text=match%20at%20L272%20Concerning%20sleep,was%20the%20only%20feature%20associated)** [sleep](https://www.nature.com/articles/s41746-025-01825-6?error=cookies_not_supported&code=6711ce5e-d4f4-48b2-ae5c-177a1675d330#:~:text=match%20at%20L272%20Concerning%20sleep,was%20the%20only%20feature%20associated) - [Bipolar - Less then 6 hours link to incipient mania](https://journalbipolardisorders.springeropen.com/articles/10.1186/s40345-021-00243-3#:~:text=Sleep%20duration%20was%20calculated%20based,360%C2%A0min) - [Bipolar - Ongoing reduction of sleep 30% of baseline increase relapse risk](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full) - [Disturbed sleep spike before psychosis relapse](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full) - [PTSD associated with more disturbed sleep](https://www.frontiersin.org/journals/digital-health/articles/10.3389/fdgth.2021.662811/full) - [Bipolar - Irregular sleep-wake cycle associated with mood instability](https://www.frontiersin.org/journals/digital-health/articles/10.3389/fdgth.2021.662811/full) - [Irregularity of sleep hours (circadian phase) associated with mood. Going to bed later then usual - Depression. Going to bed earlier, waking up earlier - manic](https://www.nature.com/articles/s41746-024-01333-z?error=cookies_not_supported&code=721f8ccf-f3da-48f7-b849-f2f7c2d7abe1#:~:text=follow,episodes%2C%20enhancing%20mood%20disorder%20management) - {Haven’t found paper on link between sleep and schizoprehnia} | - [< 6 Hours - Bipolar indicate incipient of mania](https://journalbipolardisorders.springeropen.com/articles/10.1186/s40345-021-00243-3#:~:text=Sleep%20duration%20was%20calculated%20based,360%C2%A0min) - [Sleep reduction 30%> of baseline in Bipolar increase risk](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full) (about 2 hours reduction in a 7 hours sleep duration over a few days) - Screentime/Communication - Bipolar “ **[excessive nighttime phone use](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full)** [can also disrupt sleep and trigger mood instability](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full) - As a general intervention- [“Early trials found that a](https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-025-03944-z#:~:text=Smartphone%20screen%20time%20reduction%20improves,being) **[3-week reduction in screen time](https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-025-03944-z#:~:text=Smartphone%20screen%20time%20reduction%20improves,being)** [actually improved depression and sleep quality, highlighting its clinical relevance](https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-025-03944-z#:~:text=Smartphone%20screen%20time%20reduction%20improves,being)” - - Bipolar mania “[bipolar manic episodes were accompanied by a jump in phone call frequency and text activity, alongside insomnia](https://journalbipolardisorders.springeropen.com/articles/10.1186/s40345-021-00243-3#:~:text=Sleep%20duration%20was%20calculated%20based,360%C2%A0min)” | 1. Sleep is definetly an important DP 2. Current logic of looking for changes in sleep hours, sleep segments can work, 3. So far mostly about bipolar disorder. Reduce sleep = Mania 4. Trauma/Anxiety = more disturbed sleep | **Sensor: - **Sleep (Fitbit) - Socialbility (Text/Calls) - Screen Time - FITBIT Collect Sleep Hours, Sleep Stages | | **…Appetite & Weight Changes** | significant loss or gain in appetite/weight (seen in depressive episodes and other SMI) Both – Monitored clinically as a symptom (especially in mood disorders) and studied in research (e.g. metabolic health in SMI) | Physiological | No Sensor | | | Not using | | **…Energy Level Dysregulation** | fatigue/low energy in depression vs. increased energy in mania Low energy is a clinical criterion in depression ; mania features high energy, and activity levels are tracked in research Research – Biomarker of stress reactivity; frequently observed in depression and sometimes in psychosis (not routinely measured clinically). | Physiological | - In direct proxy - Based on accelerometer, GPS, and phone use log | | | | | **Inflammation Markers** | elevated inflammatory cytokines or CRP in subsets of patients Biological indicator linked to depression, bipolar, and schizophrenia pathophysiology (investigational, not part of standard clinical assessment). | Physiological | - [There is this VitaPatch Proof of concept](https://ascpt.onlinelibrary.wiley.com/doi/10.1111/cts.13734) | | | | | **Autonomic Arousal** | e.g. heart rate variability reduction due to chronic stress/anxiety in SMI Research - Measured via physiological sensors; reduced HRV is found in schizophrenia, bipolar, and depression compared to controls | Physiological | - Lower HRV indicates higher stress or mood instability - Bipolar Disorder — **[HRV (RMSSD)](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full)** [was](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full) _[markedly lower](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full)_ [during mania compared to the same patients’ euthymia (within-subject drops with large effect sizes, Cohen’s](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full) _[g](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full)_ [~1.0](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full)) - Mood Disorder - “ [Meta-analyses confirm](https://www.nature.com/articles/s44184-024-00090-x?error=cookies_not_supported&code=3591ce40-ba82-4c5f-a540-d71a84f101f8#:~:text=Bipolar%20disorder%20,the%20sample%20size%20limited%20the) **[chronically blunted HRV in mood disorders](https://www.nature.com/articles/s44184-024-00090-x?error=cookies_not_supported&code=3591ce40-ba82-4c5f-a540-d71a84f101f8#:~:text=Bipolar%20disorder%20,the%20sample%20size%20limited%20the)****” ** - [Schizophrenia - Meta analysis found a reduced HRV across a range of psychiatric conditions, not just BD, with psychotic disorders featuring the greatest reduction. (Cite 13-16 source from here)](https://www.nature.com/articles/s44184-024-00090-x?error=cookies_not_supported&code=3591ce40-ba82-4c5f-a540-d71a84f101f8#:~:text=Bipolar%20disorder%20,the%20sample%20size%20limited%20the) - [In schizophrenia, RR SDNN was negatively correlated with positive symptoms (rho = -0.50, p = 0.007), indicating that lower HRV reflects worse symptoms](https://www.sciencedirect.com/science/article/pii/S092099641730590X) | - “[on the order of a](https://www.nature.com/articles/s44184-024-00090-x?error=cookies_not_supported&code=3591ce40-ba82-4c5f-a540-d71a84f101f8#:~:text=Bipolar%20disorder%20,the%20sample%20size%20limited%20the) **[30–50% reduction in RMSSD](https://www.nature.com/articles/s44184-024-00090-x?error=cookies_not_supported&code=3591ce40-ba82-4c5f-a540-d71a84f101f8#:~:text=Bipolar%20disorder%20,the%20sample%20size%20limited%20the)** [in some cases” before mania relapse](https://www.nature.com/articles/s44184-024-00090-x?error=cookies_not_supported&code=3591ce40-ba82-4c5f-a540-d71a84f101f8#:~:text=Bipolar%20disorder%20,the%20sample%20size%20limited%20the) - [HRV was lower in the manic state when compared to the euthymic state for all HRV metrics (](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full)_[p](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full)_ [≤ 0.02), with large to medium effect sizes (](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full)_[g](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full)_ [= 1.24 to 0.65). HRV changes were not significantly affected by age or sex.](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1250925/full) - [13https://www.nature.com/articles/s44184-024-00090-x?error=cookies_not_supported&code=3591ce40-ba82-4c5f-a540-d71a84f101f8#:~:text=Bipolar%20disorder%20,the%20sample%20size%20limited%20the](https://www.nature.com/articles/s44184-024-00090-x?error=cookies_not_supported&code=3591ce40-ba82-4c5f-a540-d71a84f101f8#ref-CR13) | 1. SMI generally have lower HRV? As if people with SMI are stuck in low HRV? 2. Tracking HRV, when lower = Increase stressors 3. Lower HRV = Mania 4. Use this to trigger EMA? ?What is a low HRV? So far it only find correlations. not direct links | **Sensors 1. **Fitbit (HRV) | | **Social Withdrawal/Isolation** | disengagement from social interactions (common early feature of psychosis, also in depression) Both – Clinically evident (patients withdrawing from friends/family) and tracked in research (as a transdiagnostic early warning sign) | Social | Mobility/Activity Sensors - Schizophrenia “ [individuals with schizophrenia traveled significantly](https://www.nature.com/articles/s41746-019-0182-1?error=cookies_not_supported&code=7eccf4d2-519e-49ff-8dc5-82fb4217dbe0#:~:text=more%20in%20the%20home%20%5B77,037) **[less distance](https://www.nature.com/articles/s41746-019-0182-1?error=cookies_not_supported&code=7eccf4d2-519e-49ff-8dc5-82fb4217dbe0#:~:text=more%20in%20the%20home%20%5B77,037)** [per day than healthy controls (median ~7 miles from home vs 12 miles in controls) and spent more time at home (77% of time vs 63% in controls)](https://www.nature.com/articles/s41746-019-0182-1?error=cookies_not_supported&code=7eccf4d2-519e-49ff-8dc5-82fb4217dbe0#:~:text=more%20in%20the%20home%20%5B77,037)” Mobility/Activity Sensors - Bipolar Disorder — “ [one digital phenotyping study noted that on days](https://www.notion.so/Clinical-Constructs-and-Digital-Phenotyping-233e037e407580fea0f7e8d8b705d0c4?pvs=21) **[distance traveled](https://www.notion.so/Clinical-Constructs-and-Digital-Phenotyping-233e037e407580fea0f7e8d8b705d0c4?pvs=21)** [fell well below a patient’s average (e.g. staying within a one-block radius), their depression severity (PHQ/PANSS scores) was worse”](https://www.notion.so/Clinical-Constructs-and-Digital-Phenotyping-233e037e407580fea0f7e8d8b705d0c4?pvs=21) Screentime and Communication — Bipolar - “ **[longer daily screen time](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#fullTextFileContent)** [was significantly associated with worse depressive symptom severity](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#fullTextFileContent)” Screentime and Communication - Bipolar Depression - “ [Patients in bipolar depression spent more time on their phones on average, and their total screen minutes per day correlated positively with depression scale scores.](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full)” | Schizoprehnia - [30% reduction in step count or location variance is considered abnormal and potential predictive of relapse into depression or social withdrawal](https://www.nature.com/articles/s41746-019-0182-1?error=cookies_not_supported&code=7eccf4d2-519e-49ff-8dc5-82fb4217dbe0#:~:text=of%20average%20distance%20travelled%20overall,of%20important%20outcomes%20in%20schizophrenia) Bipolar Depression - “ [a rule of thumb used in some digital apps is that a](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full) **[sudden increase in screen time by >1–2 hours/day](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full)** [(especially at odd hours) could indicate a depressive downturn](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full)” | 1. Reduction in acvities/GPS could indicate withdrawal, depression. 2. Cross reference to screen time, whether increased? also can be proxy for mood issues. | **Sensor 1 **. Fitbit (Steps) 2. Phone (Steps) 3. GPS 4. phone screen time | | **Functional Impairment (Social/Occupational)** | difficulties in work, school, or independent living across SMI Both – A hallmark of SMI in practice (measured by global functioning scales) and outcome in research (often remains impaired even during symptom remission) | Social | - Indirectly via GPS, Travel time, Sleep timing - “[High accuracy in the “employment” subscale suggests metrics like consistent morning location (work vs. home) and mobility patterns can indicate whether someone is holding a job” -](https://pubmed.ncbi.nlm.nih.gov/39840820/) | | | | | **Social Cognition Deficits** | impairments in understanding others (e.g. theory of mind, emotion recognition) Research – Documented in schizophrenia and bipolar (though more severe in schizophrenia) ; targeted by social skills training, but not routinely measured in general clinical exams. | Social | No Sensor | | | | | **Loneliness / Low Social Support** | subjective feeling of being alone or lacking support network Both – Frequently reported by SMI patients and associated with worse outcomes (e.g. loneliness correlates with higher risk of psychosis, bipolar episodes, and depression) . Addressed in psychosocial interventions and studied epidemiologically. | Social | - Combined **GPS, accelerometer, call/SMS**; Bluetooth proximity - [https://mhealth.jmir.org/2022/4/e34638](https://mhealth.jmir.org/2022/4/e34638) (Scoping review of 29 studies: 69 % used phones/wearables; most achieved ≥70 % accuracy classifying high-loneliness using mobility + communication features, with validated loneliness scales as ground truth) | | 1. Hmmm not reliable yet | | | **Stigma and Discrimination** | experiences of social stigma related to mental illness. Research – Not a direct symptom, but pervasive across SMI, leading to isolation and reduced help-seeking . Addressed indirectly in psychoeducation and advocacy (important for recovery outcomes). | Social | No Passive Sensor | | | | | **Family Stress / High Expressed Emotion** | family environment marked by high criticism, hostility, or over-involvement. Both – High _expressed emotion_ in relatives predicts higher relapse rates in schizophrenia and mood disorders . Clinically, family interventions aim to reduce this stress, and it’s a well-established research construct. | Social | No Passive Sensor | | | | | **Trauma History (Adverse Childhood Experiences)** | e.g. childhood abuse or neglect, which elevates risk for SMI Both – Clinicians assess trauma due to its impact on course of illness, and research shows childhood trauma increases likelihood and severity of schizophrenia, bipolar, and depression | Social | No Passive Sensor | | | | | **Socioeconomic Adversity** | poverty, unemployment, housing instability often intertwined with SMI Both – Considered in psychosocial assessments (SMI can lead to job loss and poverty, and vice versa) . Frequently studied as social determinants of mental health outcomes. | Social | No Passive Sensor | | | | | **Cognitive Impairment** | deficits in attention, memory, and executive function present across SMI Both – Clinically, patients show objective cognitive deficits (e.g. poor concentration, memory issues) and research robustly confirms pervasive neurocognitive impairment in depression, bipolar, and schizophrenia | Behavioral | -Communication/Texting — Mania - “**[Typing dynamics](https://www.sciencedirect.com/science/article/abs/pii/S0920996419301082)** [can even change – e.g. rapid, error-filled texting has been observed before manic relapses (Arevian et al., 2020)](https://www.sciencedirect.com/science/article/abs/pii/S0920996419301082)” | | 1. Increased in error-filled texting (can we detect that?) number of times backspace entered? or typo? = Mania? | **Sensors 1. Tapping speed ** | | **Anhedonia** | loss of ability to experience pleasure or interest (common to depression and negative symptoms of schizophrenia) Both – Core clinical symptom in major depression and schizophrenia , and extensively studied in research (e.g. reward processing deficits). | Behavioral | No Passive Sensor | | 1. Use Active input - Mood Log | | | **Avolition** | lack of motivation or drive to initiate and persist in activities (seen in schizophrenia and severe depression) Both – Clinically recognized (especially as a negative symptom in psychosis) and linked to functional disability ; also investigated in research on motivational deficits. | Behavioral | Mobility/Activity - “[lower mobility correlated with](https://www.nature.com/articles/s41746-019-0182-1?error=cookies_not_supported&code=7eccf4d2-519e-49ff-8dc5-82fb4217dbe0#:~:text=more%20in%20the%20home%20%5B77,037) **[greater negative symptom severity](https://www.nature.com/articles/s41746-019-0182-1?error=cookies_not_supported&code=7eccf4d2-519e-49ff-8dc5-82fb4217dbe0#:~:text=more%20in%20the%20home%20%5B77,037)** [(especially apathy and amotivation](https://www.nature.com/articles/s41746-019-0182-1?error=cookies_not_supported&code=7eccf4d2-519e-49ff-8dc5-82fb4217dbe0#:~:text=more%20in%20the%20home%20%5B77,037))” | | 1. Reduce activities = negative symptoms? Then cross reference to see if sleep hours changed? | **Sensor 1. GPS ** | | **Depressed Mood** | pervasive sadness or low mood (appearing not only in MDD but also as comorbid depression in schizophrenia and bipolar) Both – Primary clinical symptom in depression; also frequently co-occurs in schizophrenia (up to ~50% experience depressive episodes) and in bipolar disorder. Widely studied in all these disorders. | Behavioral | Mobility/Activity - Bipolar Depression - [“in bipolar depression, passively sensed activity tends to drop: fewer steps, more sedentary hours, and shorter travel distances have all been associated with higher depression scores](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#:~:text=Pro%20%EF%AC%81%20le%20Description)” Communication - Bipolar Disorder - “ [Passive phone logs in bipolar disorder show that during depression, patients initiate](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#fullTextFileContent) **[fewer outgoing calls and answer fewer incoming calls](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#fullTextFileContent)**[, proportional to depression severity.](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#fullTextFileContent) | As a general intervention- [“Early trials found that a](https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-025-03944-z#:~:text=Smartphone%20screen%20time%20reduction%20improves,being) **[3-week reduction in screen time](https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-025-03944-z#:~:text=Smartphone%20screen%20time%20reduction%20improves,being)** [actually improved depression and sleep quality, highlighting its clinical relevance](https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-025-03944-z#:~:text=Smartphone%20screen%20time%20reduction%20improves,being)” | 1. Reduced activity, reduced travel distance = higher depression 2. Reduced outgoing calls, fewer answered incoming calls = depression 3. Can create a mini-challenge to encourage 3 weeks of reduce screen time to improve depression and sleep quality | **Sensor 1. GPS 2. Socialbility (Calls/Text) 3. Screen time ** | | **Anxiety Symptoms** | excessive worry, fear, or physiological anxiety (often comorbid across SMI diagnoses) Both – Clinicians often find anxiety in schizophrenia, bipolar, and depression (e.g. >38% of schizophrenia patients have significant anxiety symptoms) . Anxiety is also a transdiagnostic research focus (e.g. treatments targeting anxiety across disorders). | Behavioral | - Many papers - [https://pubmed.ncbi.nlm.nih.gov/38807465/](https://pubmed.ncbi.nlm.nih.gov/38807465/) ( [need deeper study](https://chatgpt.com/share/6879f79f-73e0-8002-bbc7-9e6aab419a8b)) | | | | | **Irritability/Anger** | proneness to anger and irritability (notable in bipolar mania, depression, and even some schizophrenia cases) Both – Assessed clinically (irritable mood can signal a depressive or manic episode) and included in cross-cutting symptom measures . Research examines irritability as a cross-diagnostic dimension. | Behavioral | Mood State maybe possible..? | | | | | **Emotional Dysregulation (Mood Lability)** | difficulty regulating emotions, with rapid or intense mood swings Both – Seen in various disorders (e.g. mood lability in psychosis spectrum and bipolar is elevated and tied to worse social outcomes ). Addressed in therapies (DBT, etc.) and studied as a transdiagnostic process. | Behavioral | - Mania - “[L](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#:~:text=Geolocation%20Shorter%20distance%20traveled%20associated,with%20severity%20of%20bipolar%20depression)**[onger distances traveled](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#:~:text=Geolocation%20Shorter%20distance%20traveled%20associated,with%20severity%20of%20bipolar%20depression)** [were associated with higher manic symptom severity](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#:~:text=Geolocation%20Shorter%20distance%20traveled%20associated,with%20severity%20of%20bipolar%20depression)” - Mania - “ [during manic states, patients often exhibit a flurry of communication: one study found](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#fullTextFileContent) **[more frequent outgoing text messages](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#fullTextFileContent)** [(and unusually short, terse replies from others) correlated with higher mania ratings](https://www.researchgate.net/publication/383546908_Sleep_and_circadian_disruption_in_bipolar_disorders_From_psychopathology_to_digital_phenotyping_in_clinical_practice_PCN_Psychiatry_and_Clinical_Neurosciences#fullTextFileContent)” - Bipolar mania “ [bipolar manic episodes were accompanied by a jump in phone call frequency and text activity, alongside insomnia](https://journalbipolardisorders.springeropen.com/articles/10.1186/s40345-021-00243-3#:~:text=Sleep%20duration%20was%20calculated%20based,360%C2%A0min)” | -Schizoprehnia - [30% reduction in step count or location variance is considered abnormal and potential predictive of relapse into depression or social withdrawal](https://www.nature.com/articles/s41746-019-0182-1?error=cookies_not_supported&code=7eccf4d2-519e-49ff-8dc5-82fb4217dbe0#:~:text=of%20average%20distance%20travelled%20overall,of%20important%20outcomes%20in%20schizophrenia) - Mania - “watch for sudden spikes in activity (e.g. **a sharp increase in daily steps or outings by >50% above baseline**) as a warning of mania” (Citation needed) - [look for “an](https://www.nature.com/articles/s41746-024-01333-z?error=cookies_not_supported&code=721f8ccf-f3da-48f7-b849-f2f7c2d7abe1#:~:text=on%20an%20individual%E2%80%99s%20sleep,episodes%2C%20enhancing%20mood%20disorder%20management) **[elevated activity level for several days](https://www.nature.com/articles/s41746-024-01333-z?error=cookies_not_supported&code=721f8ccf-f3da-48f7-b849-f2f7c2d7abe1#:~:text=on%20an%20individual%E2%80%99s%20sleep,episodes%2C%20enhancing%20mood%20disorder%20management)** [coupled with reduced need for sleep, which reliably predicted impending manic mood shifts (AUC ~0.98 for mania prediction using actigraphy)”](https://www.nature.com/articles/s41746-024-01333-z?error=cookies_not_supported&code=721f8ccf-f3da-48f7-b849-f2f7c2d7abe1#:~:text=on%20an%20individual%E2%80%99s%20sleep,episodes%2C%20enhancing%20mood%20disorder%20management) - Screentime/Communication - Bipolar “ **[excessive nighttime phone use](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full)** [can also disrupt sleep and trigger mood instability](https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.641241/full) | 1. Increase distance travel associated with mania 2. Increased communication = mania 3. Sudden lncrease of call frequency = mania 4. Reduction of activities, location = depression = social withdrawal 5. Increase screentime at night - can be a EMA (= distrup sleep, and next day mood instability) | **Sensors** 1. GPS 2. Socioability 3. Fitbit (Steps) 4. Phone usage - screen time 5. Sleep | | **Psychotic Symptoms (Hallucinations & Delusions)** | perceptual distortions and false beliefs that can occur in schizophrenia, but also in severe mood disorders Both – Hallucinations and delusions are core clinical features of schizophrenia and schizoaffective disorder, and can emerge in bipolar mania or severe depression with psychotic features . Research examines these symptoms’ mechanisms across diagnoses. | Behavioral | - Mobility/Activity - Schizophrenia - “[Less GPS mobility was related to greater negative symptom severity, particularly diminished motivation,](https://www.nature.com/articles/s41746-019-0182-1?error=cookies_not_supported&code=7eccf4d2-519e-49ff-8dc5-82fb4217dbe0#:~:text=of%20average%20distance%20travelled%20overall,of%20important%20outcomes%20in%20schizophrenia)” -Communication - [In schizophrenia, reduced social calls or messages often precede relapse; one mobile health study noted that days with](https://www.sciencedirect.com/science/article/abs/pii/S0920996419301082#:~:text=measures%20of%20social%20behavior%20can,early%20indication%20of%20relapse%20events) **[no communication activity](https://www.sciencedirect.com/science/article/abs/pii/S0920996419301082#:~:text=measures%20of%20social%20behavior%20can,early%20indication%20of%20relapse%20events)** [spiked in the week before a psychotic relapse](https://www.sciencedirect.com/science/article/abs/pii/S0920996419301082#:~:text=measures%20of%20social%20behavior%20can,early%20indication%20of%20relapse%20events) | - Schizophrenia - “[The rate of behavioral anomalies (e.g. unusually low movement for that person) in the](https://www.nature.com/articles/s41398-020-01123-7?error=cookies_not_supported&code=306b8113-d82e-4540-b8e7-b024f1ed731e#:~:text=own%20environments,outcomes%20and%20relapse%2C%20that%20had) **[2 weeks preceding a relapse was ~71% higher](https://www.nature.com/articles/s41398-020-01123-7?error=cookies_not_supported&code=306b8113-d82e-4540-b8e7-b024f1ed731e#:~:text=own%20environments,outcomes%20and%20relapse%2C%20that%20had)** [than during stable periods](https://www.nature.com/articles/s41398-020-01123-7?error=cookies_not_supported&code=306b8113-d82e-4540-b8e7-b024f1ed731e#:~:text=own%20environments,outcomes%20and%20relapse%2C%20that%20had)” - Schizophrenia - “ [combined anomalies in mobility and sociability rose sharply before clinical relapse, allowing prediction of relapse with](https://www.nature.com/articles/s41398-020-01123-7?error=cookies_not_supported&code=309daa37-30fa-4552-a97c-b1e2fe4c03a9#:~:text=significant%20deviations%20from%20an%20individual%E2%80%99s,utilized%2C%20and%20clinical%20integration%20achieved) **[89% sensitivity and 75% specificity](https://www.nature.com/articles/s41398-020-01123-7?error=cookies_not_supported&code=309daa37-30fa-4552-a97c-b1e2fe4c03a9#:~:text=significant%20deviations%20from%20an%20individual%E2%80%99s,utilized%2C%20and%20clinical%20integration%20achieved)****”**** - **Digital phenotyping systems therefore set simple thresholds like _“no calls/texts for 2 days”_ or _“>50% drop in social interactions”_ as potential alerts for isolation and worsening negative symptoms (if weekly outgoing calls drop 30% below personal average, flag for review” or “if daily screen time >2× baseline, send an alert.— EMPOWER trial - COMMUNICATION - “ [Trigger alerts when SD deviation occurs](https://www.nature.com/articles/s41398-020-01123-7?error=cookies_not_supported&code=309daa37-30fa-4552-a97c-b1e2fe4c03a9#:~:text=The%20potential%20of%20anomaly%20detection,serve%20as%20tailoring%20variables%20in)” | 1. Again, reduce location = increase negative symptoms 2. Reduced calls/messages = relapsing 3. Changes in data trend compare to 71% of past data point to higher risk of relapse in the next 2 weeks? | **Sensor 1. GPS - movement 2. Sociability ** | | **Suicidal Ideation/Behavior** | thoughts of suicide or suicide attempts (high risk across all serious mental illnesses) Both – Critically monitored in clinical settings (SMI patients have a markedly elevated risk of suicide; up to half may attempt in their lifetime) . Also a major research and public health focus (risk factors and prevention). | Behavioral | ?? | | | | | **Substance Use** | alcohol or drug misuse co-occurring with mental illness (common across SMI) Both – Assessed clinically due to its prevalence (e.g. ~50% of individuals with schizophrenia also have substance abuse) and studied in research as a factor that exacerbates outcomes. | Behavioral | NO sensor | | | | | **Aggression/Agitation** | aggressive behavior or extreme agitation (can accompany psychosis or mania in some cases) Both – Managed clinically when present (e.g. agitation in psychiatric emergencies) and investigated in research (violence risk, often linked with untreated psychosis or substance use). | Behavioral | No Sensor | | | |